Watermelon(Citrullus lanatus),one of the top five fruit crops based on the gross tonnage and cultivated area globally,holds major economic importance in agriculture and contributes substantially to farmers’incomes.Wa...Watermelon(Citrullus lanatus),one of the top five fruit crops based on the gross tonnage and cultivated area globally,holds major economic importance in agriculture and contributes substantially to farmers’incomes.Watermelon cultivation relies on sexual reproduction,with meiosis playing a pivotal role in this process.However,our understanding of the meiotic mechanism in watermelon remains limited.In this study,we utilized CRISPR/Cas9 technology to target ClDYAD,a homolog of the meiosis-related genes AtDYAD and OsAM1,and conducted functional analysis to explore the initiation of meiosis in watermelon.ClDYAD was highly expressed in tender male flowers both before and during the early stages of meiosis.Mutations in ClDYAD led to meiotic arrest at the leptotene stage,impeding the normal enlargement of microspore mother cells and megasporocytes.This resulted in the absence of pollen in anthers and seed abortion.ClDYAD physically interacts with the protein encoded by Cla97C07G137480,which was identified as a switch-associated protein 70-like protein(ClSWAP-70).The expression pattern of ClSWAP-70 in tender male flowers of various sizes matched with the changes in ClDYAD mRNA levels.These findings shed light on the molecular mechanisms governing the initiation of meiosis in watermelon,offering valuable insights into male and female sterility in Cucurbitaceae plants and guiding future research.展开更多
Meiosis is the process of producing haploid gametes through a series of complex chromosomal events and the coordinated action of various proteins.The mitochondrial protease complex(ClpXP),which consists of caseinolyti...Meiosis is the process of producing haploid gametes through a series of complex chromosomal events and the coordinated action of various proteins.The mitochondrial protease complex(ClpXP),which consists of caseinolytic mitochondrial matrix peptidase X(ClpX)and caseinolytic protease P(ClpP)and mediates the degradation of misfolded,damaged,and oxidized proteins,is essential for maintaining mitochondrial homeostasis.ClpXP has been implicated in meiosis regulation,but its precise role is currently unknown.In this study,we engineered an inducible male germ cell-specific knockout caseinolytic mitochondrial matrix peptidase X(Clpx^(cKO))mouse model to investigate the function of ClpX in meiosis.We found that disrupting Clpx in male mice induced germ cell apoptosis and led to an absence of sperm in the epididymis.Specifically,it caused asynapsis of homologous chromosomes and impaired meiotic recombination,resulting in meiotic arrest in the zygotene-to-pachytene transition phase.The loss of ClpX compromised the double-strand break(DSB)repair machinery by markedly reducing the recruitment of DNA repair protein RAD51 homolog 1(RAD51)to DSB sites.This dysfunction may be due to an insufficient supply of energy from the aberrant mitochondria in Clpx^(cKO) spermatocytes,as discerned by electron microscopy.Furthermore,ubiquitination signals on chromosomes and the expression of oxidative phosphorylation subunits were both significantly attenuated in Clpx^(cKO) spermatocytes.Taken together,we propose that ClpX is essential for maintaining mitochondrial protein homeostasis and ensuring homologous chromosome pairing,synapsis,and recombination in spermatocytes during meiotic prophase I.展开更多
CtBP-interacting protein(CtIP)is known for its multifaceted roles in DNA repair and genomic stability,directing the homologous recombination-mediated DNA double-stranded break repair pathway via DNA end resection,an e...CtBP-interacting protein(CtIP)is known for its multifaceted roles in DNA repair and genomic stability,directing the homologous recombination-mediated DNA double-stranded break repair pathway via DNA end resection,an essential error-free repair process vital for genome stability.Mammalian oocytes are highly prone to DNA damage accumulation due to prolonged G2/prophase arrest.Here,we explore the functions of CtIP in meiotic cell cycle regulation via a mouse oocyte model.Depletion of CtIP by siRNA injection results in delayed germinal vesicle breakdown and failed polar body extrusion.Mechanistically,CtIP deficiency increases DNA damage and decreases the expression and nuclear entry of CCNB1,resulting in marked impairment of meiotic resumption,which can be rescued by exogenous CCNB1 overexpression.Furthermore,depletion of CtIP disrupts microtubule-organizing centers coalescence at spindle poles as indicated by failed accumulation ofγ-tubulin,p-Aurora kinase A,Kif2A,and TPX2,leading to abnormal spindle assembly and prometaphase arrest.These results provide valuable insights into the important roles of CtIP in the G2/M checkpoint and spindle assembly in mouse oocyte meiotic cell cycle regulation.展开更多
Microtubule-severing enzymes(MTSEs)play important roles in mitosis and meiosis of the primitive organisms.However,their roles in mammalian female meiosis,which accounts for over 80%of gamete-originated human reproduct...Microtubule-severing enzymes(MTSEs)play important roles in mitosis and meiosis of the primitive organisms.However,their roles in mammalian female meiosis,which accounts for over 80%of gamete-originated human reproductive diseases,remain unexplored.In the current study,we reported that katanin-like 2(KL2)was the only MTSE concentrating at chromosomes.Furthermore,the knockdown of KL2 significantly reduced the chromosome-based increase in the microtubule(MT)polymer,increased aberrant kinetochore-MT(K-MT)attachment,delayed meiosis,and severely affected normal fertility.We demonstrated that the inhibition of aurora B,a key kinase for correcting aberrant K-MT attachment,significantly eliminated KL2 expression from chromosomes.Additionally,KL2 interacted with phosphorylated eukaryotic elongation factor-2 kinase,and they competed for chromosome binding.Phosphorylated KL2 was also localized at spindle poles,with its phosphorylation regulated by extracellular signal-regulated kinase 1/2.In summary,the current study reveals a novel function of MTSEs in mammalian female meiosis and demonstrates that multiple kinases coordinate to regulate the levels of KL2 at chromosomes.展开更多
One of the prominent cell cycle related modifications of histone proteins, whose function is correlated with chromosome condensation, is the phosphorylation of histone H3. Wheat (Triticum aestivum L.) mitotic and meio...One of the prominent cell cycle related modifications of histone proteins, whose function is correlated with chromosome condensation, is the phosphorylation of histone H3. Wheat (Triticum aestivum L.) mitotic and meiotic cells were analyzed with indirect immunoflurorescence labeling with an antibody recognizing histone H3 phosphorylated at Serine 10 to study the localization of phosphorylated histone H3 at mitosis and meiosis. Our results showed that, during mitotic division, the phosphoryiation of H3 started from early prophase and vanished at telophase, remaining mainly in the pericentromeric regions at metaphase and anaphase. During meiotic division, phosphorylation of H3 initiated at the transition from leptotene to zygotene and remained uniform, along the chromosomes from prophase I until telophase whereas it showed slightly stronger in the pericentromeric regions than along the chromosome arms from metaphase II until Lelophase II The different patterns of H3 phophorylation at mitosis and meiosis in wheat suggested that this evolutionarily conserved post-translational chromatin modification might be involved in more roles besides chromosome condensation.展开更多
[Objective] The aim of this study was to establish a feasible squashing technique for chromosome and obtain data of rice chromosome. [Method] With the materials of rice root tips and anther, the specimen was prepared ...[Objective] The aim of this study was to establish a feasible squashing technique for chromosome and obtain data of rice chromosome. [Method] With the materials of rice root tips and anther, the specimen was prepared by the modified squash method, and microscopic observation of mitosis and meiosis in rice cells was also carried out. [ Result] Mitosis in rice cells included interphase, prophase, metaphase, anaphase and telophase. Chromosome in metaphase shortened to the minmum, which was a good time for observing and investigating chromosome. However, meiosis in rice cells included meiosis Ⅰ and meiosis Ⅱ. Chromosome replication appeared in meiosis Ⅰ, while cell division only appeared in meiosis Ⅱ. [ Conclusion] The modified squashing technique for rice chromosome can obtain accurate data of rice chromosome, which provides evidence for genetic breeding.展开更多
The Arabidopsis SDS （SOLO DANCERS） and RCK （ROCK-N-ROLLERS） genes are important for male meiosis, but it is still unknown whether they represent conserved functions in plants. We have performed phylogenetic analys...The Arabidopsis SDS （SOLO DANCERS） and RCK （ROCK-N-ROLLERS） genes are important for male meiosis, but it is still unknown whether they represent conserved functions in plants. We have performed phylogenetic analyses of SDS and RCK and their respective homologs, and identified their putative orthologs in poplar and rice. Quantitative real-time RT-PCR analysis indicated that rice SDS and RCK are expressed preferentially in young flowers, and transgenic RNAi rice lines with reduced expression of these genes exhibited normal vegetative development, but showed significantly reduced fertility with partially sterile flowers and defective pollens. SDS deficiency also caused a decrease in pollen amounts. Further cytological examination of male meiocytes revealed that the SDS deficiency led to defects in homolog interaction and bivalent formation in meiotic prophase I, and RCK deficiency resulted in defective meiotic crossover formation. These results indicate that rice SDS and RCK genes have similar functions to their Arabidopsis orthologs. Because rice and Arabidopsis, respectively, are members of monocots and eudicots, two largest groups of flowering plants, our results suggest that the functions of SDS and RCK are likely conserved in flowering plants.展开更多
Longiflorum and Asiatic lilies of the genus Lilium of the family Liliaceae are two important groups of modem lily cultivars. One of the main trends of lily breeding is to realize introgression between these groups. Wi...Longiflorum and Asiatic lilies of the genus Lilium of the family Liliaceae are two important groups of modem lily cultivars. One of the main trends of lily breeding is to realize introgression between these groups. With cut style pollination and embryo rescue, distant hybrids between the two groups have been obtained. However, the FI hybrids are highly sterile or some of them could produce a small number of 2n gametes, and their BC1 progenies are usually triploids. Dutch lily breeders have selected many cultivars from these BC1 progenies based on their variation. It is presumably suggested that such variation could be caused by intergenomic recombination and abnormal meiosis during gamete formation in F1 hybrids of Longiflorum × Asiatic （LA） hybrids in Lilium. Therefore, the meiotic process of ten F1 LA hybrids was cytologically investigated using genomic in situ hybridization and traditional cytological methods in the present research. The results showed that： at metaphase I, the homoeologous chromosome pairing among different F1 hybrids ranged from 2.0 to 11.4 bivalents formed by homoeologous chromosomes per pollen mother cell （PMC）, and very few multivalents, and even very few bivalents were formed by two chromosomes within one genome rather than homoeologous chromosomes in some PMCs; at anaphase I, all biva- lents were disjoined and most univalents were divided. Both the disjoined bivalents （half-bivalents） and the divided univalents （sister chromatids） moved to the opposite poles, and then formed two groups of chromosomes; because the two resulting half-bivalents retained their axes in the cell undisturbed, many crossover types, including single crossovers, three strand double crossovers, four strand double crossovers, four strand triple crossovers, and four strand multiple crossovers between the non-sister chromatids in the tetrads of bivalents, were clearly inferred by analyzing the breakpoints on the disjoined bivalents. The present investigation not only explained the reason for sterility of the Fl LA hybrids and the variation of their BCx progenies, but also provided a new method to analyze crossover types in other F1 interspecific hybrids as well.展开更多
MSH5, a member of the MutS homolog DNA mismatch repair protein family, has been shown to be required for proper homologous chromosome recombination in diverse organisms such as mouse, budding yeast and Caenorhabditis ...MSH5, a member of the MutS homolog DNA mismatch repair protein family, has been shown to be required for proper homologous chromosome recombination in diverse organisms such as mouse, budding yeast and Caenorhabditis elegans. In this paper, we show that a mutant Arabidopsis plant carrying the putative disrupted AtMSH5 gene exhibits defects during meiotic division, producing a proportion of nonviable pollen grains and abnormal embryo sacs, and thereby leading to a decrease in fertility. AtMSH5 expression is confined to meiotic floral buds, which is consistent with a possible role during meiosis. Cytological analysis of male meiosis revealed the presence of numerous univalents from diplotene to metaphase I, which were associated with a great reduction in chiasma frequencies. The average number of residual chiasmata in the mutant is reduced to 2.54 per meiocyte, which accounts for ~25% of the amount in the wild type. Here, quantitative cytogenetical analysis reveals that the residual chiasmata in Afresh5 mutants are randomly distributed among meiocytes, suggesting that AtMSH5 has an essential role during interferencesensitive chiasma formation. Taken together, the evidence indicates that AtMSH5 promotes homologous recombination through facilitating chiasma formation during prophase Ⅰ in Arabidopsis.展开更多
Germ-line cells are responsible for transmitting genetic and epigenetic information across generations, and ensuring the creation of new individuals from one generation to the next. Gametogenesis process requires seve...Germ-line cells are responsible for transmitting genetic and epigenetic information across generations, and ensuring the creation of new individuals from one generation to the next. Gametogenesis process requires several rigorous steps, including primordial germ cell （PGC） specification, proliferation, migration to the gonadal ridges and differentiation into mature gametes such as sperms and oocytes. But this process is not clearly explored because a small number of PGCs are deeply embedded in the developing embryo. In the attempt to establish an in vitro model for understanding gametogenesis process well, several groups have made considerable progress in differen- tiating embryonic stem cells （ESCs） and adult stem cells （ASCs） into germ-like cells over the past ten years. These stem cell-derived germ cells appear to he capable of undergoing meiosis and generating both male and female gametes. But most of gametes turn out to be not fully functional due to their abnormal meiosis process compared to endogenous germ cells. Therefore, a robust system of differentiating stem cells into germ cells would enable us to investigate the genetic, epigenetic and environmental factors associated with germ cell development. Here, we review the stem cell-derived germ cell development, and discuss the potential and challenges in the differentiation of functional germ cells from stem cells.展开更多
Programmed DNA double-strand breaks(DSBs)are necessary for meiosis in mammals.A sufficient number of DSBs ensure the normal pairing/synapsis of homologous chromosomes.Abnormal DSB repair undermines meiosis,leading to ...Programmed DNA double-strand breaks(DSBs)are necessary for meiosis in mammals.A sufficient number of DSBs ensure the normal pairing/synapsis of homologous chromosomes.Abnormal DSB repair undermines meiosis,leading to sterility in mammals.The DSBs that initiate recombination are repaired as crossovers and noncrossovers,and crossovers are required for correct chromosome separation.Thus,the placement,timing,and frequency of crossover formation must be tightly controlled.Importantly,mutations in many genes related to the formation and repair of DSB result in infertility in humans.These mutations cause nonobstructive azoospermia in men,premature ovarian insufficiency and ovarian dysgenesis in women.Here,we have illustrated the formation and repair of DSB in mammals,summarized major factors influencing the formation of DSB and the theories of crossover regulation.展开更多
Interspecific hybridization and allopolyploidization contribute to the improvement of many important crops. Recently, we successfully developed an amphidiploid from an interspecific cross between cucumber(Cucumis sati...Interspecific hybridization and allopolyploidization contribute to the improvement of many important crops. Recently, we successfully developed an amphidiploid from an interspecific cross between cucumber(Cucumis sativus, 2n = 2x = 14) and its relative C. hystrix(2n = 2x = 24) followed by chemical induction of chromosome doubling. The resulting allotetraploid plant was self-pollinated for three generations. The fertility and seed set of the amphidiploid plants were very low. In this study, we investigated the meiotic chromosome behavior in pollen mother cells with the aid of fluorescence in situ hybridization, aiming to identify the reasons for the low fertility and seed set in the amphidiploid plants. Homologous chromosome pairing appeared normal, but chromosome laggards were common, owing primarily to asynchronous meiosis of chromosomes from the two donor genomes. We suggest that asynchronous meiotic rhythm between the two parental genomes is the main reason for the low fertility and low seed set of the C. hystrix–cucumber amphidiploid plants.展开更多
Male meiosis is a complex process whereby spermatocytes undergo cell division to form haploid cells.This review focuses on the role of retinoic acid(RA)in meiosis,as well as several processes regulated by RA before ce...Male meiosis is a complex process whereby spermatocytes undergo cell division to form haploid cells.This review focuses on the role of retinoic acid(RA)in meiosis,as well as several processes regulated by RA before cell entry into meiosis that are critical for proper meiotic entry and completion.Here,we discuss RA metabolism in the testis as well as the roles of stimulated by retinoic acid gene 8(STRA8)and MEIOSIN,which are responsive to RA and are critical for meiosis.We assert that transcriptional regulation in the spermatogonia is critical for successful meiosis.展开更多
Proper chromosome separation in both mitosis and meiosis depends on the correct connection between kinetochores of chromosomes and spindle microtubules. Kinetochore dysfunction can lead to unequal distribution of chro...Proper chromosome separation in both mitosis and meiosis depends on the correct connection between kinetochores of chromosomes and spindle microtubules. Kinetochore dysfunction can lead to unequal distribution of chromosomes during cell division and result in aneuploidy, thus kinetochores are critical for faithful segregation of chromosomes. Centromere protein A(CENP-A) is an important component of the inner kinetochore plate. Multiple studies in mitosis have found that deficiencies in CENP-A could result in structural and functional changes of kinetochores, leading to abnormal chromosome segregation, aneuploidy and apoptosis in cells. Here we report the expression and function of CENP-A during mouse oocyte meiosis. Our study found that microinjection of CENP-A blocking antibody resulted in errors of homologous chromosome segregation and caused aneuploidy in eggs. Thus, our findings provide evidence that CENP-A is critical for the faithful chromosome segregation during mammalian oocyte meiosis.展开更多
Meiotic recombination is essential for reciprocal exchange of genetic information between homologous chromosomes and their subsequent proper segregation in sexually reproducing organisms. MLH1 and MLH3 belong to meios...Meiotic recombination is essential for reciprocal exchange of genetic information between homologous chromosomes and their subsequent proper segregation in sexually reproducing organisms. MLH1 and MLH3 belong to meiosis-specific members of the Mut L-homolog family, which are required for normal level of crossovers(COs) in some eukaryotes. However, their functions in plants need to be further elucidated.Here, we report the identification of Os MLH1 and reveal its functions during meiosis in rice. Using CRISPRCas9 approach, two independent mutants, Osmlh1-1 and Osmlh1-2, are generated and exhibited significantly reduced male fertility. In Osmlh1-1, the clearance of PAIR2 is delayed and partial ZEP1 proteins are not loaded into the chromosomes, which might be due to the deficient in resolution of interlocks at late zygotene. Thus, Os MLH1 is required for the assembly of synapsis complex. In Osmlh1-1, CO number is dropped by ~53% and the distribution of residual COs is consistent with predicted Poisson distribution,indicating that Os MLH1 is essential for the formation of interference-sensitive COs(class I COs). Os MLH1 interacts with Os MLH3 through their C-terminal domains. Mutation in Os MLH3 also affects the pollen fertility. Thus, our experiments reveal that the conserved heterodimer Mut Lg(Os MLH1-Os MLH3) is essential for the formation of class I COs in rice.展开更多
Meiotic prophase I is a long and complex phase. Homologous recombination is an important process that occurs between homologous chromosomes during meiotic prophase I. Formation of chiasmata, which hold homologous chro...Meiotic prophase I is a long and complex phase. Homologous recombination is an important process that occurs between homologous chromosomes during meiotic prophase I. Formation of chiasmata, which hold homologous chromosomes together until the metaphase I to anaphase I transition, is critical for proper chromosome segregation. Recent studies have suggested that the SPO 11 proteins have conserved functions in a number of organisms in generating sites of double-stranded DNA breaks （DSBs） that are thought to be the starting points of homologous recombination. Processing of these sites of DSBs requires the function of RecA homologs, such as RAD5 1, DMC 1, and others, as suggested by mutant studies; thus the failure to repair these meiotic DSBs results in abnormal chromosomal alternations, leading to disrupted meiosis. Recent discoveries on the functions of these RecA homologs have improved the understanding of the mechanisms underlying meiotic homologous recombination.展开更多
Meiosis is a specialized cell division for producing haploid gametes in sexually reproducing organisms.In this study,we have independently identified a novel meiosis protein male meiosis recombination regulator(MAMERR...Meiosis is a specialized cell division for producing haploid gametes in sexually reproducing organisms.In this study,we have independently identified a novel meiosis protein male meiosis recombination regulator(MAMERR)/4930432 K21 Rik and showed that it is indispensable for meiosis prophase I progression in male mice.Using super-resolution structured illumination microscopy,we found that MAMERR functions at the same double-strand breaks as the replication protein A and meiosis-specific with OB domains/spermatogenesis associated 22 complex.We generated a Mamerr-deficient mouse model by deleting exons 3 e6 and found that most of Mamerrà/àspermatocytes were arrested at pachynema and failed to progress to diplonema,although they exhibited almost intact synapsis and progression to the pachytene stage along with XY body formation.Further mechanistic studies revealed that the recruitment of DMC1/RAD51 and heat shock factor 2 ebinding protein in Mamerrà/àspermatocytes was only mildly impaired with a partial reduction in double-strand break repair,whereas a substantial reduction in ubiquitination on the autosomal axes and on the XY body appeared as a major phenotype in Mamerrà/àspermatocytes.We propose that MAMERR may participate in meiotic prophase I progression by regulating the ubiquitination of key meiotic proteins on autosomes and XY chromosomes,and in the absence of MAMERR,the repressed ubiquitination of key meiotic proteins leads to pachytene arrest and cell death.展开更多
Adhesions between different cells and extracellular matrix have been studied extensively in vitro, but little is known about their functions in testicular tissue counterparts. Spermatogonia and their companion somatic...Adhesions between different cells and extracellular matrix have been studied extensively in vitro, but little is known about their functions in testicular tissue counterparts. Spermatogonia and their companion somatic cells maintain a close association throughout spermatogenesis and this association is necessary for normal spermatogenesis. In order to keep the relative integrity of the testicular tissues, and to detect the development in vitro, culture testicular tissues in a three- dimensional （3D） agarose matrix was examined. Testicular tissues isolated from 6.5 d postpartum （dpp） mouse were cultured on the top of the matrix for 26 d with a medium height up to 4/5 of the 3D agarose matrix. The results showed that in this 3D culture environment, each type of testicular cells kept the same structure, localization and function as in vivo and might be more biologically relevant to living organisms. After culture, germ cell marker VASA and meiosis markers DAZL and SCP3 showed typical positive analysed by immunofluorescence staining and RT-PCR. It demonstrated that this 3D culture system was able to maintain the number of germ cells and promote the meiosis initiation of male germ cells.展开更多
In the sexually reproductive organisms, gametes are produced by meiosis following a limited mitotic amplification. However, the intrinsic program switching cells from mitotic to meiotic cycle is unclear.Alternative po...In the sexually reproductive organisms, gametes are produced by meiosis following a limited mitotic amplification. However, the intrinsic program switching cells from mitotic to meiotic cycle is unclear.Alternative polyadenylation（APA） is a highly conserved means of gene regulation and is achieved by the RNA 30-processing machinery to generate diverse 30 UTR profiles. In Drosophila spermatogenesis, we observed distinct profiles of transcriptome-wide 30 UTR between mitotic and meiotic cells. In mutant germ cells stuck in mitosis, 30 UTRs of hundreds of genes were consistently shifted. Remarkably, altering the levels of multiple 30-processing factors disrupted germline＇s progression to meiosis, indicative of APA＇s active role in this transition. An RNA-binding protein（RBP） Tut could directly bind 30 UTRs of 30-processing factors whose expressions were repressed in the presence of Tut-containing complex. Further,we demonstrated that this RBP complex could execute the repression post-transcriptionally by recruiting CCR4/Twin of deadenylation complex. Thus, we propose that an RBP complex regulates the dynamic APA profile to promote the mitosis-to-meiosis transition.展开更多
During meiosis in flowering plants,degradation of the callose wall in tetrads releases newly produced microspores,which develop into mature pollen grains.In this study,we identified zbs1,a male-sterile mutant of naked...During meiosis in flowering plants,degradation of the callose wall in tetrads releases newly produced microspores,which develop into mature pollen grains.In this study,we identified zbs1,a male-sterile mutant of naked oat（Avena nuda L.）that displayed complete spikelet sterility due to inviable mature pollen.The abnormal pollen grains originated from microspores with a defective callose wall and cell plate during meiosis.The defective callose wall and cell plate of the zbs1 mutant were detected by the labeling of cell wall epitopes（β-1,3-glucan） with immunogold during meiosis,and an abnormal chromosome configuration was observed by propidium iodide staining.The mature pollen grains of the zbs1 mutant were irregular in shape,and abnormal germination was observed by scanning electron microscopy.Together,our results indicate that the cause of male sterility in zbs1 is abnormal meiosis.展开更多
基金supported by Shaanxi Provincial Central Leading Local Science and Technology Development Special Fund(Grant No.2023ZY-QYCX-02)the National Youth Talent Program(Grant No.A279021801)+3 种基金Earmarked Fund for China Agriculture Research System(Grant No.CARS-25)Key R&D Program of Shaanxi Province(Grant Nos.2023-YBNY-008 and 2024NC-YBXM-032)the Fundamental Research Funds for the Central Universities(Grant Nos.10120221103 and 2452022111)the Science and Technology Innovation Team of Shaanxi(Grant No.2021TD-32).
文摘Watermelon(Citrullus lanatus),one of the top five fruit crops based on the gross tonnage and cultivated area globally,holds major economic importance in agriculture and contributes substantially to farmers’incomes.Watermelon cultivation relies on sexual reproduction,with meiosis playing a pivotal role in this process.However,our understanding of the meiotic mechanism in watermelon remains limited.In this study,we utilized CRISPR/Cas9 technology to target ClDYAD,a homolog of the meiosis-related genes AtDYAD and OsAM1,and conducted functional analysis to explore the initiation of meiosis in watermelon.ClDYAD was highly expressed in tender male flowers both before and during the early stages of meiosis.Mutations in ClDYAD led to meiotic arrest at the leptotene stage,impeding the normal enlargement of microspore mother cells and megasporocytes.This resulted in the absence of pollen in anthers and seed abortion.ClDYAD physically interacts with the protein encoded by Cla97C07G137480,which was identified as a switch-associated protein 70-like protein(ClSWAP-70).The expression pattern of ClSWAP-70 in tender male flowers of various sizes matched with the changes in ClDYAD mRNA levels.These findings shed light on the molecular mechanisms governing the initiation of meiosis in watermelon,offering valuable insights into male and female sterility in Cucurbitaceae plants and guiding future research.
基金supported by the Shenzhen Science and Technology Program,China(No.KQTD20190929172749226).
文摘Meiosis is the process of producing haploid gametes through a series of complex chromosomal events and the coordinated action of various proteins.The mitochondrial protease complex(ClpXP),which consists of caseinolytic mitochondrial matrix peptidase X(ClpX)and caseinolytic protease P(ClpP)and mediates the degradation of misfolded,damaged,and oxidized proteins,is essential for maintaining mitochondrial homeostasis.ClpXP has been implicated in meiosis regulation,but its precise role is currently unknown.In this study,we engineered an inducible male germ cell-specific knockout caseinolytic mitochondrial matrix peptidase X(Clpx^(cKO))mouse model to investigate the function of ClpX in meiosis.We found that disrupting Clpx in male mice induced germ cell apoptosis and led to an absence of sperm in the epididymis.Specifically,it caused asynapsis of homologous chromosomes and impaired meiotic recombination,resulting in meiotic arrest in the zygotene-to-pachytene transition phase.The loss of ClpX compromised the double-strand break(DSB)repair machinery by markedly reducing the recruitment of DNA repair protein RAD51 homolog 1(RAD51)to DSB sites.This dysfunction may be due to an insufficient supply of energy from the aberrant mitochondria in Clpx^(cKO) spermatocytes,as discerned by electron microscopy.Furthermore,ubiquitination signals on chromosomes and the expression of oxidative phosphorylation subunits were both significantly attenuated in Clpx^(cKO) spermatocytes.Taken together,we propose that ClpX is essential for maintaining mitochondrial protein homeostasis and ensuring homologous chromosome pairing,synapsis,and recombination in spermatocytes during meiotic prophase I.
基金supported by National Natural Science Foundation of China(32570854)Science and Technology Program of Guangzhou,China(2023A03J0258)Guangdong Basic and Applied Basic Research Foundation,China(2023B1515120027)。
文摘CtBP-interacting protein(CtIP)is known for its multifaceted roles in DNA repair and genomic stability,directing the homologous recombination-mediated DNA double-stranded break repair pathway via DNA end resection,an essential error-free repair process vital for genome stability.Mammalian oocytes are highly prone to DNA damage accumulation due to prolonged G2/prophase arrest.Here,we explore the functions of CtIP in meiotic cell cycle regulation via a mouse oocyte model.Depletion of CtIP by siRNA injection results in delayed germinal vesicle breakdown and failed polar body extrusion.Mechanistically,CtIP deficiency increases DNA damage and decreases the expression and nuclear entry of CCNB1,resulting in marked impairment of meiotic resumption,which can be rescued by exogenous CCNB1 overexpression.Furthermore,depletion of CtIP disrupts microtubule-organizing centers coalescence at spindle poles as indicated by failed accumulation ofγ-tubulin,p-Aurora kinase A,Kif2A,and TPX2,leading to abnormal spindle assembly and prometaphase arrest.These results provide valuable insights into the important roles of CtIP in the G2/M checkpoint and spindle assembly in mouse oocyte meiotic cell cycle regulation.
基金supported by the Youth Program of National Natural Science Foundation of China(Grant No.82001539 to Leilei Gao)the Zhejiang Province Health Innovation Talent Project(Grant No.2021RC001 to Zhen Jin)+1 种基金the General Program of the National Natural Science Foundation of China(Grant No.31671561 to Dong Zhang)the Regional Program of National Natural Science Foundation of China(Grant No.82260126 to Xiaocong Liu).
文摘Microtubule-severing enzymes(MTSEs)play important roles in mitosis and meiosis of the primitive organisms.However,their roles in mammalian female meiosis,which accounts for over 80%of gamete-originated human reproductive diseases,remain unexplored.In the current study,we reported that katanin-like 2(KL2)was the only MTSE concentrating at chromosomes.Furthermore,the knockdown of KL2 significantly reduced the chromosome-based increase in the microtubule(MT)polymer,increased aberrant kinetochore-MT(K-MT)attachment,delayed meiosis,and severely affected normal fertility.We demonstrated that the inhibition of aurora B,a key kinase for correcting aberrant K-MT attachment,significantly eliminated KL2 expression from chromosomes.Additionally,KL2 interacted with phosphorylated eukaryotic elongation factor-2 kinase,and they competed for chromosome binding.Phosphorylated KL2 was also localized at spindle poles,with its phosphorylation regulated by extracellular signal-regulated kinase 1/2.In summary,the current study reveals a novel function of MTSEs in mammalian female meiosis and demonstrates that multiple kinases coordinate to regulate the levels of KL2 at chromosomes.
文摘One of the prominent cell cycle related modifications of histone proteins, whose function is correlated with chromosome condensation, is the phosphorylation of histone H3. Wheat (Triticum aestivum L.) mitotic and meiotic cells were analyzed with indirect immunoflurorescence labeling with an antibody recognizing histone H3 phosphorylated at Serine 10 to study the localization of phosphorylated histone H3 at mitosis and meiosis. Our results showed that, during mitotic division, the phosphoryiation of H3 started from early prophase and vanished at telophase, remaining mainly in the pericentromeric regions at metaphase and anaphase. During meiotic division, phosphorylation of H3 initiated at the transition from leptotene to zygotene and remained uniform, along the chromosomes from prophase I until telophase whereas it showed slightly stronger in the pericentromeric regions than along the chromosome arms from metaphase II until Lelophase II The different patterns of H3 phophorylation at mitosis and meiosis in wheat suggested that this evolutionarily conserved post-translational chromatin modification might be involved in more roles besides chromosome condensation.
基金Supported by Natural Science Fund of Henan Province (2008A208019)~~
文摘[Objective] The aim of this study was to establish a feasible squashing technique for chromosome and obtain data of rice chromosome. [Method] With the materials of rice root tips and anther, the specimen was prepared by the modified squash method, and microscopic observation of mitosis and meiosis in rice cells was also carried out. [ Result] Mitosis in rice cells included interphase, prophase, metaphase, anaphase and telophase. Chromosome in metaphase shortened to the minmum, which was a good time for observing and investigating chromosome. However, meiosis in rice cells included meiosis Ⅰ and meiosis Ⅱ. Chromosome replication appeared in meiosis Ⅰ, while cell division only appeared in meiosis Ⅱ. [ Conclusion] The modified squashing technique for rice chromosome can obtain accurate data of rice chromosome, which provides evidence for genetic breeding.
文摘The Arabidopsis SDS （SOLO DANCERS） and RCK （ROCK-N-ROLLERS） genes are important for male meiosis, but it is still unknown whether they represent conserved functions in plants. We have performed phylogenetic analyses of SDS and RCK and their respective homologs, and identified their putative orthologs in poplar and rice. Quantitative real-time RT-PCR analysis indicated that rice SDS and RCK are expressed preferentially in young flowers, and transgenic RNAi rice lines with reduced expression of these genes exhibited normal vegetative development, but showed significantly reduced fertility with partially sterile flowers and defective pollens. SDS deficiency also caused a decrease in pollen amounts. Further cytological examination of male meiocytes revealed that the SDS deficiency led to defects in homolog interaction and bivalent formation in meiotic prophase I, and RCK deficiency resulted in defective meiotic crossover formation. These results indicate that rice SDS and RCK genes have similar functions to their Arabidopsis orthologs. Because rice and Arabidopsis, respectively, are members of monocots and eudicots, two largest groups of flowering plants, our results suggest that the functions of SDS and RCK are likely conserved in flowering plants.
基金the National Natural Science Foundation of China（No.30471222）
文摘Longiflorum and Asiatic lilies of the genus Lilium of the family Liliaceae are two important groups of modem lily cultivars. One of the main trends of lily breeding is to realize introgression between these groups. With cut style pollination and embryo rescue, distant hybrids between the two groups have been obtained. However, the FI hybrids are highly sterile or some of them could produce a small number of 2n gametes, and their BC1 progenies are usually triploids. Dutch lily breeders have selected many cultivars from these BC1 progenies based on their variation. It is presumably suggested that such variation could be caused by intergenomic recombination and abnormal meiosis during gamete formation in F1 hybrids of Longiflorum × Asiatic （LA） hybrids in Lilium. Therefore, the meiotic process of ten F1 LA hybrids was cytologically investigated using genomic in situ hybridization and traditional cytological methods in the present research. The results showed that： at metaphase I, the homoeologous chromosome pairing among different F1 hybrids ranged from 2.0 to 11.4 bivalents formed by homoeologous chromosomes per pollen mother cell （PMC）, and very few multivalents, and even very few bivalents were formed by two chromosomes within one genome rather than homoeologous chromosomes in some PMCs; at anaphase I, all biva- lents were disjoined and most univalents were divided. Both the disjoined bivalents （half-bivalents） and the divided univalents （sister chromatids） moved to the opposite poles, and then formed two groups of chromosomes; because the two resulting half-bivalents retained their axes in the cell undisturbed, many crossover types, including single crossovers, three strand double crossovers, four strand double crossovers, four strand triple crossovers, and four strand multiple crossovers between the non-sister chromatids in the tetrads of bivalents, were clearly inferred by analyzing the breakpoints on the disjoined bivalents. The present investigation not only explained the reason for sterility of the Fl LA hybrids and the variation of their BCx progenies, but also provided a new method to analyze crossover types in other F1 interspecific hybrids as well.
基金Acknowledgments This work was supported by the National Natural Science Foundation of China （grant number 30470173）. The plant expression vector was kindly provided by Flanders Interuniversity Institute for Biotechnology （VIB）, Belgium.
文摘MSH5, a member of the MutS homolog DNA mismatch repair protein family, has been shown to be required for proper homologous chromosome recombination in diverse organisms such as mouse, budding yeast and Caenorhabditis elegans. In this paper, we show that a mutant Arabidopsis plant carrying the putative disrupted AtMSH5 gene exhibits defects during meiotic division, producing a proportion of nonviable pollen grains and abnormal embryo sacs, and thereby leading to a decrease in fertility. AtMSH5 expression is confined to meiotic floral buds, which is consistent with a possible role during meiosis. Cytological analysis of male meiosis revealed the presence of numerous univalents from diplotene to metaphase I, which were associated with a great reduction in chiasma frequencies. The average number of residual chiasmata in the mutant is reduced to 2.54 per meiocyte, which accounts for ~25% of the amount in the wild type. Here, quantitative cytogenetical analysis reveals that the residual chiasmata in Afresh5 mutants are randomly distributed among meiocytes, suggesting that AtMSH5 has an essential role during interferencesensitive chiasma formation. Taken together, the evidence indicates that AtMSH5 promotes homologous recombination through facilitating chiasma formation during prophase Ⅰ in Arabidopsis.
基金supported by the National Basic Research Program of China(973 Program)(Grant Nos.2013CB947903 and 2012CB944401)Program for New Century Excellent Talents in University of China(Grant No.NCET-12-1026)Foundation of Distinguished Young Scholars of Shandong Province in China(Grant No.JQ201109)
文摘Germ-line cells are responsible for transmitting genetic and epigenetic information across generations, and ensuring the creation of new individuals from one generation to the next. Gametogenesis process requires several rigorous steps, including primordial germ cell （PGC） specification, proliferation, migration to the gonadal ridges and differentiation into mature gametes such as sperms and oocytes. But this process is not clearly explored because a small number of PGCs are deeply embedded in the developing embryo. In the attempt to establish an in vitro model for understanding gametogenesis process well, several groups have made considerable progress in differen- tiating embryonic stem cells （ESCs） and adult stem cells （ASCs） into germ-like cells over the past ten years. These stem cell-derived germ cells appear to he capable of undergoing meiosis and generating both male and female gametes. But most of gametes turn out to be not fully functional due to their abnormal meiosis process compared to endogenous germ cells. Therefore, a robust system of differentiating stem cells into germ cells would enable us to investigate the genetic, epigenetic and environmental factors associated with germ cell development. Here, we review the stem cell-derived germ cell development, and discuss the potential and challenges in the differentiation of functional germ cells from stem cells.
基金This work is supported by National Key Research&Development Program of China(No.2018YFC1003400)National Natural Science Foundation of China(No.31771588)the Strategic Collaborative Research Program of the Ferring Institute of Reproductive Medicine(No.FIRMC200509)to MCL.
文摘Programmed DNA double-strand breaks(DSBs)are necessary for meiosis in mammals.A sufficient number of DSBs ensure the normal pairing/synapsis of homologous chromosomes.Abnormal DSB repair undermines meiosis,leading to sterility in mammals.The DSBs that initiate recombination are repaired as crossovers and noncrossovers,and crossovers are required for correct chromosome separation.Thus,the placement,timing,and frequency of crossover formation must be tightly controlled.Importantly,mutations in many genes related to the formation and repair of DSB result in infertility in humans.These mutations cause nonobstructive azoospermia in men,premature ovarian insufficiency and ovarian dysgenesis in women.Here,we have illustrated the formation and repair of DSB in mammals,summarized major factors influencing the formation of DSB and the theories of crossover regulation.
基金supported by Agriculture and Food Research Initiative Competitive Grant 2013-67013-21105 from the U.S. Department of Agriculture National Institute of Food to YWthe National Natural Science Foundation of China to YH (No. 31271350)
文摘Interspecific hybridization and allopolyploidization contribute to the improvement of many important crops. Recently, we successfully developed an amphidiploid from an interspecific cross between cucumber(Cucumis sativus, 2n = 2x = 14) and its relative C. hystrix(2n = 2x = 24) followed by chemical induction of chromosome doubling. The resulting allotetraploid plant was self-pollinated for three generations. The fertility and seed set of the amphidiploid plants were very low. In this study, we investigated the meiotic chromosome behavior in pollen mother cells with the aid of fluorescence in situ hybridization, aiming to identify the reasons for the low fertility and seed set in the amphidiploid plants. Homologous chromosome pairing appeared normal, but chromosome laggards were common, owing primarily to asynchronous meiosis of chromosomes from the two donor genomes. We suggest that asynchronous meiotic rhythm between the two parental genomes is the main reason for the low fertility and low seed set of the C. hystrix–cucumber amphidiploid plants.
基金This work is supported by the National Institutes of Health(R01 HD10808 awarded to MDG).
文摘Male meiosis is a complex process whereby spermatocytes undergo cell division to form haploid cells.This review focuses on the role of retinoic acid(RA)in meiosis,as well as several processes regulated by RA before cell entry into meiosis that are critical for proper meiotic entry and completion.Here,we discuss RA metabolism in the testis as well as the roles of stimulated by retinoic acid gene 8(STRA8)and MEIOSIN,which are responsive to RA and are critical for meiosis.We assert that transcriptional regulation in the spermatogonia is critical for successful meiosis.
基金supported by the National Natural Science Foundation of China(No.30930065 and No.31271605)
文摘Proper chromosome separation in both mitosis and meiosis depends on the correct connection between kinetochores of chromosomes and spindle microtubules. Kinetochore dysfunction can lead to unequal distribution of chromosomes during cell division and result in aneuploidy, thus kinetochores are critical for faithful segregation of chromosomes. Centromere protein A(CENP-A) is an important component of the inner kinetochore plate. Multiple studies in mitosis have found that deficiencies in CENP-A could result in structural and functional changes of kinetochores, leading to abnormal chromosome segregation, aneuploidy and apoptosis in cells. Here we report the expression and function of CENP-A during mouse oocyte meiosis. Our study found that microinjection of CENP-A blocking antibody resulted in errors of homologous chromosome segregation and caused aneuploidy in eggs. Thus, our findings provide evidence that CENP-A is critical for the faithful chromosome segregation during mammalian oocyte meiosis.
基金supported by the National Natural Science Foundation of China(31630054,31425018,31821005)Program for Chinese Outstanding Talents in Agricultural Scientific Research。
文摘Meiotic recombination is essential for reciprocal exchange of genetic information between homologous chromosomes and their subsequent proper segregation in sexually reproducing organisms. MLH1 and MLH3 belong to meiosis-specific members of the Mut L-homolog family, which are required for normal level of crossovers(COs) in some eukaryotes. However, their functions in plants need to be further elucidated.Here, we report the identification of Os MLH1 and reveal its functions during meiosis in rice. Using CRISPRCas9 approach, two independent mutants, Osmlh1-1 and Osmlh1-2, are generated and exhibited significantly reduced male fertility. In Osmlh1-1, the clearance of PAIR2 is delayed and partial ZEP1 proteins are not loaded into the chromosomes, which might be due to the deficient in resolution of interlocks at late zygotene. Thus, Os MLH1 is required for the assembly of synapsis complex. In Osmlh1-1, CO number is dropped by ~53% and the distribution of residual COs is consistent with predicted Poisson distribution,indicating that Os MLH1 is essential for the formation of interference-sensitive COs(class I COs). Os MLH1 interacts with Os MLH3 through their C-terminal domains. Mutation in Os MLH3 also affects the pollen fertility. Thus, our experiments reveal that the conserved heterodimer Mut Lg(Os MLH1-Os MLH3) is essential for the formation of class I COs in rice.
基金The authors thank Alexandra Surcel and Carey L Hendrix Lord for helpful comments on this manuscript.The work in our laboratory is supported by grants from the National Science Foundation(IBN-0077832,MCB-9896340,MCB-0092075)the National Institutes of Health(R0 1 GM63871)+3 种基金the US Department of Agriculture(2001-35301-10570 and 2003-35301-13313)Wuxing L was partially supported by the Intercollege Graduate Degree Program in Plant PhysiologyHong M gratefully acknowledges the support of the John Simon Guggenheim Foundationthe National Institutes of Health(F33 GM72245-1).
文摘Meiotic prophase I is a long and complex phase. Homologous recombination is an important process that occurs between homologous chromosomes during meiotic prophase I. Formation of chiasmata, which hold homologous chromosomes together until the metaphase I to anaphase I transition, is critical for proper chromosome segregation. Recent studies have suggested that the SPO 11 proteins have conserved functions in a number of organisms in generating sites of double-stranded DNA breaks （DSBs） that are thought to be the starting points of homologous recombination. Processing of these sites of DSBs requires the function of RecA homologs, such as RAD5 1, DMC 1, and others, as suggested by mutant studies; thus the failure to repair these meiotic DSBs results in abnormal chromosomal alternations, leading to disrupted meiosis. Recent discoveries on the functions of these RecA homologs have improved the understanding of the mechanisms underlying meiotic homologous recombination.
基金supported by grants from the Hong Kong Research Grant Council(17114920,K.L.and R.H.W.L.)the University of Hong Kong(K.L.)+3 种基金the Sanming Project of Medicine in Shenzhen,China(SZSM201612083,W.S.B.Y.)High Level-Hospital Program,Health Commission of Guangdong Province,China(HKUSZH201902018,K.L.)Shenzhen-Hong Kong Innovation Circle Type D(K.L.)a grant from the NIH/NIGMS(National Institute of General Medical Sciences)R35GM118052(P.J.W.)
文摘Meiosis is a specialized cell division for producing haploid gametes in sexually reproducing organisms.In this study,we have independently identified a novel meiosis protein male meiosis recombination regulator(MAMERR)/4930432 K21 Rik and showed that it is indispensable for meiosis prophase I progression in male mice.Using super-resolution structured illumination microscopy,we found that MAMERR functions at the same double-strand breaks as the replication protein A and meiosis-specific with OB domains/spermatogenesis associated 22 complex.We generated a Mamerr-deficient mouse model by deleting exons 3 e6 and found that most of Mamerrà/àspermatocytes were arrested at pachynema and failed to progress to diplonema,although they exhibited almost intact synapsis and progression to the pachytene stage along with XY body formation.Further mechanistic studies revealed that the recruitment of DMC1/RAD51 and heat shock factor 2 ebinding protein in Mamerrà/àspermatocytes was only mildly impaired with a partial reduction in double-strand break repair,whereas a substantial reduction in ubiquitination on the autosomal axes and on the XY body appeared as a major phenotype in Mamerrà/àspermatocytes.We propose that MAMERR may participate in meiotic prophase I progression by regulating the ubiquitination of key meiotic proteins on autosomes and XY chromosomes,and in the absence of MAMERR,the repressed ubiquitination of key meiotic proteins leads to pachytene arrest and cell death.
基金supported by the National Natural Science Foundation of China(31272518)the program for the New Century Excellent Talents of Ministry of Education of China(NCET-09-0654)+1 种基金the Doctoral Fund of Ministry of Education of P.R.China(RFDP,20120204110030)the Fundamental Research Funds for the Central Universities,China(QN2011012)
文摘Adhesions between different cells and extracellular matrix have been studied extensively in vitro, but little is known about their functions in testicular tissue counterparts. Spermatogonia and their companion somatic cells maintain a close association throughout spermatogenesis and this association is necessary for normal spermatogenesis. In order to keep the relative integrity of the testicular tissues, and to detect the development in vitro, culture testicular tissues in a three- dimensional （3D） agarose matrix was examined. Testicular tissues isolated from 6.5 d postpartum （dpp） mouse were cultured on the top of the matrix for 26 d with a medium height up to 4/5 of the 3D agarose matrix. The results showed that in this 3D culture environment, each type of testicular cells kept the same structure, localization and function as in vivo and might be more biologically relevant to living organisms. After culture, germ cell marker VASA and meiosis markers DAZL and SCP3 showed typical positive analysed by immunofluorescence staining and RT-PCR. It demonstrated that this 3D culture system was able to maintain the number of germ cells and promote the meiosis initiation of male germ cells.
基金supported by National Key Basic Research Program of China(No.2013CB945000)National Science Foundation of China(No.31471345)
文摘In the sexually reproductive organisms, gametes are produced by meiosis following a limited mitotic amplification. However, the intrinsic program switching cells from mitotic to meiotic cycle is unclear.Alternative polyadenylation（APA） is a highly conserved means of gene regulation and is achieved by the RNA 30-processing machinery to generate diverse 30 UTR profiles. In Drosophila spermatogenesis, we observed distinct profiles of transcriptome-wide 30 UTR between mitotic and meiotic cells. In mutant germ cells stuck in mitosis, 30 UTRs of hundreds of genes were consistently shifted. Remarkably, altering the levels of multiple 30-processing factors disrupted germline＇s progression to meiosis, indicative of APA＇s active role in this transition. An RNA-binding protein（RBP） Tut could directly bind 30 UTRs of 30-processing factors whose expressions were repressed in the presence of Tut-containing complex. Further,we demonstrated that this RBP complex could execute the repression post-transcriptionally by recruiting CCR4/Twin of deadenylation complex. Thus, we propose that an RBP complex regulates the dynamic APA profile to promote the mitosis-to-meiosis transition.
基金supported by the Natural Science Foundation of Hebei Province,China(C2004000747)
文摘During meiosis in flowering plants,degradation of the callose wall in tetrads releases newly produced microspores,which develop into mature pollen grains.In this study,we identified zbs1,a male-sterile mutant of naked oat（Avena nuda L.）that displayed complete spikelet sterility due to inviable mature pollen.The abnormal pollen grains originated from microspores with a defective callose wall and cell plate during meiosis.The defective callose wall and cell plate of the zbs1 mutant were detected by the labeling of cell wall epitopes（β-1,3-glucan） with immunogold during meiosis,and an abnormal chromosome configuration was observed by propidium iodide staining.The mature pollen grains of the zbs1 mutant were irregular in shape,and abnormal germination was observed by scanning electron microscopy.Together,our results indicate that the cause of male sterility in zbs1 is abnormal meiosis.
