Sterols are essential components of the cell membrane lipid bilayer that include molecules such as cholesterol and desmosterol, which are significantly found in the spermatozoa of several animal species. However, the ...Sterols are essential components of the cell membrane lipid bilayer that include molecules such as cholesterol and desmosterol, which are significantly found in the spermatozoa of several animal species. However, the presence of desmosterol in rabbit semen has never been investigated. The aims of this study were to characterize the sterol composition of subfractions of ejaculated rabbit semen and evaluate the in vitro effects of sterol on the spermatozoa acrosome reaction and motility. Two sterols, occurring prevalently in the free form （94.3%）, were identified in whole semen collected from 10 fertile New Zealand White rabbits, specifically desmosterol （58.5% of total sterols） and cholesterol （35.9% of total sterols）. Desmosterol was the predominant sterol found in all subfractions of rabbit semen, varying from 56.7% （in the prostatic secretory granules, PSGs） to 63.8% （in the seminal plasma）. Spermatozoa contained an intermediate proportion of desmosterol （59.8%）, which was asymmetrically distributed between the heads （52.0% of the total content of sterols） and the tails （81.8%）. Results showed that both desmosterol and cholesterol can be transferred from the PSGs to the spermatozoa and are equally effective in inhibiting in vitro spermatozoa capacitation at a concentration higher than 1 mg L^-1. In contrast, neither desmosterol nor cholesterol had a significant effect on spermatozoa motility. Thus, it was concluded that, the various fractions of rabbit seminal fluid differ from each other in sterol composition and quantity, probably due to their different functional properties, and these fractions may undergo significant sterol changes depending on the stage of spermatozoa capacitation.展开更多
Insects have to obtain sterols from food due to the inability to synthesize this essential nutrient de novo.For lepidopteran insects,they can convert a variety of phytosterols into cholesterol to meet their growth nee...Insects have to obtain sterols from food due to the inability to synthesize this essential nutrient de novo.For lepidopteran insects,they can convert a variety of phytosterols into cholesterol to meet their growth needs.The final step of the cholesterol biosynthesis is the metabolism of desmosterol catalyzed by 24-dehydrocholesterol reductase(DHCR24).In this study,we identified a DHCR24 homolog in the cotton bollworm Helicoverpa armigera,designated as H.armigera 24-dehydrocholesterol reductase(HaDHCR24)-1.The quantitative expression analyses indicated that HaDHCR24-1 was highly enriched in the midgut where dietary sterol uptake occurs.Compared to the control,the DHCR24-1 mutant larvae generated by clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated nuclease 9 technology accumulated more desmosterol in the gut,while the content of cholesterol was significantly reduced.A similar phenomenon was observed when the DHCR24 inhibitor,amiodarone,was applied to the insects.Moreover,DHCR24-1 played an important role for the usage ofβ-sitosterol,a major sterol in plants,in H.armigera,and loss of function of DHCR24-1 resulted in higher mortality onβ-sitosterol.However,the DHCR24 homolog does not necessarily exist in the genomes of all insects.The loss of this gene occurred more frequently in the insects feeding on animals,which further support the role of DHCR24-1 in using phytosterols.This gene may have important potential in developing new strategies to control herbivory pests in Lepidoptera and other insect orders.展开更多
The LXRs?agonist, 24S,25-epoxycholesterol 1,was synthesized stereoselectively (100% d.e.) in 56% overall yield from methyl hyodeoxycholanate 4 in 9 steps with des-mosterol acetate 11 as the key intermediate and the mo...The LXRs?agonist, 24S,25-epoxycholesterol 1,was synthesized stereoselectively (100% d.e.) in 56% overall yield from methyl hyodeoxycholanate 4 in 9 steps with des-mosterol acetate 11 as the key intermediate and the modified Sharpless asymmetric dihydroxylation as the key step. TheLXRa subtype selective agonist 5a,6a:24S,25-diepoxycho-lesterol 2 and the novel LXRs?ligand 5b,6b:24S,25-diepo-xycholesterol 3 were also synthesized from 1.展开更多
文摘Sterols are essential components of the cell membrane lipid bilayer that include molecules such as cholesterol and desmosterol, which are significantly found in the spermatozoa of several animal species. However, the presence of desmosterol in rabbit semen has never been investigated. The aims of this study were to characterize the sterol composition of subfractions of ejaculated rabbit semen and evaluate the in vitro effects of sterol on the spermatozoa acrosome reaction and motility. Two sterols, occurring prevalently in the free form （94.3%）, were identified in whole semen collected from 10 fertile New Zealand White rabbits, specifically desmosterol （58.5% of total sterols） and cholesterol （35.9% of total sterols）. Desmosterol was the predominant sterol found in all subfractions of rabbit semen, varying from 56.7% （in the prostatic secretory granules, PSGs） to 63.8% （in the seminal plasma）. Spermatozoa contained an intermediate proportion of desmosterol （59.8%）, which was asymmetrically distributed between the heads （52.0% of the total content of sterols） and the tails （81.8%）. Results showed that both desmosterol and cholesterol can be transferred from the PSGs to the spermatozoa and are equally effective in inhibiting in vitro spermatozoa capacitation at a concentration higher than 1 mg L^-1. In contrast, neither desmosterol nor cholesterol had a significant effect on spermatozoa motility. Thus, it was concluded that, the various fractions of rabbit seminal fluid differ from each other in sterol composition and quantity, probably due to their different functional properties, and these fractions may undergo significant sterol changes depending on the stage of spermatozoa capacitation.
基金supported by funds awarded to X.J.by the National Natural Science Foundation of China(32070506&32372542).
文摘Insects have to obtain sterols from food due to the inability to synthesize this essential nutrient de novo.For lepidopteran insects,they can convert a variety of phytosterols into cholesterol to meet their growth needs.The final step of the cholesterol biosynthesis is the metabolism of desmosterol catalyzed by 24-dehydrocholesterol reductase(DHCR24).In this study,we identified a DHCR24 homolog in the cotton bollworm Helicoverpa armigera,designated as H.armigera 24-dehydrocholesterol reductase(HaDHCR24)-1.The quantitative expression analyses indicated that HaDHCR24-1 was highly enriched in the midgut where dietary sterol uptake occurs.Compared to the control,the DHCR24-1 mutant larvae generated by clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated nuclease 9 technology accumulated more desmosterol in the gut,while the content of cholesterol was significantly reduced.A similar phenomenon was observed when the DHCR24 inhibitor,amiodarone,was applied to the insects.Moreover,DHCR24-1 played an important role for the usage ofβ-sitosterol,a major sterol in plants,in H.armigera,and loss of function of DHCR24-1 resulted in higher mortality onβ-sitosterol.However,the DHCR24 homolog does not necessarily exist in the genomes of all insects.The loss of this gene occurred more frequently in the insects feeding on animals,which further support the role of DHCR24-1 in using phytosterols.This gene may have important potential in developing new strategies to control herbivory pests in Lepidoptera and other insect orders.
基金supported by the National Natural Science Foundation of China(Grant No.20072047)the State Key Laboratory of Biological Organic Chemistry in Shanghai Institute of Organic Chemistry,Chongqing Science and Technology Committee(Grant No.6617)the Third Military Medical University.
文摘The LXRs?agonist, 24S,25-epoxycholesterol 1,was synthesized stereoselectively (100% d.e.) in 56% overall yield from methyl hyodeoxycholanate 4 in 9 steps with des-mosterol acetate 11 as the key intermediate and the modified Sharpless asymmetric dihydroxylation as the key step. TheLXRa subtype selective agonist 5a,6a:24S,25-diepoxycho-lesterol 2 and the novel LXRs?ligand 5b,6b:24S,25-diepo-xycholesterol 3 were also synthesized from 1.
