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21.
Geographically distant populations of oak leafroller moth (Tortrix viridana L.) were characterized by the frequency uniformity for most often alleles and differentiation for rare ones in the esterase and protease loci. Opposite tendency was observed at the subpopulational level. It was supposed that the distinctive spatial distribution of the often and rare alleles was due to different sensitivity of the given groups to the factors of a dynamics. Natural selection and stochastic processes play a major role in the dynamics of often and rare alleles, respectively. 相似文献
22.
Females of the sea urchin Strongylocentrotus purpuratus differ in the structures of their egg jelly sulfated fucans 总被引:1,自引:0,他引:1
The egg jelly coats of sea urchins contain sulfated fucans which bind to a
sperm surface receptor glycoprotein to initiate the signal transduction
events resulting in the sperm acrosome reaction. The acrosome reaction is
an ion channel regulated exocytosis which is an obligatory event for sperm
binding to, and fusion with, the egg. Approximately 90% of individual
females of the sea urchin Strongylocentrotus purpuratus spawned eggs having
only one of two possible sulfated fucan electrophoretic isotypes, a slow
migrating (sulfated fucan I), or a fast migrating (sulfated fucan II)
isotype. The remaining 10% of females spawned eggs having both sulfated
fucan isotypes. The two sulfated fucan isotypes were purified from egg
jelly coats and their structures determined by NMR spectroscopy and
methylation analysis. Both sulfated fucans are linear polysaccharides
composed of 1-->3-linked alpha-L-fucopyranosyl units. Sulfated fucan I
is entirely sulfated at the O -2 position but with a heterogeneous
sulfation pattern at O -4 position. Sulfated fucan II is composed of a
regular repeating sequence of 3 residues, as follows: [3-alpha-L-Fuc p -
2,4(OSO3)-1-->3-alpha-L-Fuc p -4(OSO3)-1-->3-alpha-L-Fuc p -4(OSO3)-
1]n. Both purified sulfated fucans have approximately equal potency in
inducing the sperm acrosome reaction. The significance of two structurally
different sulfated fucans in the egg jelly coat of this species could
relate to the finding that the sperm receptor protein which binds sulfated
fucan contains two carbohydrate recognition modules of the C-type lectin
variety which differ by 50% in their primary structure.
相似文献
23.
24.
On efficient probability forecasting systems 总被引:1,自引:0,他引:1
25.
Simchuk AP 《T?Sitologii?a i genetika》2001,35(5):25-29
A mating system on the esterase locus Est-4 was studied in a natural population of oak leaf-roller moth Tortrix viridana L. Frequency-dependent sexual selection was revealed, which manifested itself in a "rare-type advantage". On the basis of obtained data, a new hypothesis for explanation of the "rare-type advantage" phenomenon is proposed. The hypothesis proceeds from the genetically determined choice of sexual partner, depending on the degree of phenotypic likeness. 相似文献
26.
Mtawa AP Mkulama Sandra Chishimba Jay Sikalima Petrica Rouse Philip E Thuma Sungano Mharakurwa 《Malaria journal》2008,7(1):1-4
Background
Artemisinin and its derivatives have been used for falciparum malaria treatment in China since late 1970s. Monotherapy and uncontrolled use of artemisinin drugs were common practices for a long period of time. In vitro tests showed that the susceptibility of Plasmodium falciparum to artemisinins was declining in China. A concern was raised about the resistance to artemisinins of falciparum malaria in the country. It has been reported that in vitro artemisinin resistance was associated with the S769N mutation in the PfATPase6 gene. The main purpose of this study was to investigate whether that mutation has occurred in field isolates from China.Methods
Plasmodium falciparum field isolates were collected in 2006–2007 from Hainan and Yunnan provinces, China. A nested PCR-sequencing assay was developed to analyse the genotype of the PfATPase6 S769N polymorphism in the P. falciparum field isolates.Results
The genotyping results of six samples could not be obtained due to failure of PCR amplification, but no S769N mutation was detected in any of the 95 samples successfully analysed.Conclusion
The results indicate that the S769N mutation in the PfATPase6 gene is not present in China, suggesting that artemisinin resistance has not yet developed, but the situation needs to be watched very attentively. 相似文献27.
A new species of Microsporidia, Pleistiophora carpocapsae sp. n., a parasite of caterpillars and pupae of the codling moth, is described from Moldavia. It is noteworthy that one sporant forms pansporoblasts containing from 4 to 64 sporoblasts and then the same number of spores. 相似文献
28.
29.
Divya T. Kandala Nimmy Mohan Vivekanand A Sudheesh AP Reshmi G Rakesh S. Laishram 《Nucleic acids research》2016,44(2):811-823
Almost all eukaryotic mRNAs have a poly (A) tail at the 3′-end. Canonical PAPs (PAPα/γ) polyadenylate nuclear pre-mRNAs. The recent identification of the non-canonical Star-PAP revealed specificity of nuclear PAPs for pre-mRNAs, yet the mechanism how Star-PAP selects mRNA targets is still elusive. Moreover, how Star-PAP target mRNAs having canonical AAUAAA signal are not regulated by PAPα is unclear. We investigate specificity mechanisms of Star-PAP that selects pre-mRNA targets for polyadenylation. Star-PAP assembles distinct 3′-end processing complex and controls pre-mRNAs independent of PAPα. We identified a Star-PAP recognition nucleotide motif and showed that suboptimal DSE on Star-PAP target pre-mRNA 3′-UTRs inhibit CstF-64 binding, thus preventing PAPα recruitment onto it. Altering 3′-UTR cis-elements on a Star-PAP target pre-mRNA can switch the regulatory PAP from Star-PAP to PAPα. Our results suggest a mechanism of poly (A) site selection that has potential implication on the regulation of alternative polyadenylation. 相似文献
30.
H Arslan A Aktaş E Elibol OBB Esener AP Türkmen KK Yurt 《Biotechnic & histochemistry》2016,91(4):277-282
Diclofenac sodium (DS) is used primarily to treat fever and to alleviate pain and inflammation. We investigated the effects of DS exposure during gestation on the testes of rat pups to investigate the safety of its use during the prenatal period. Pregnant rats were separated into control, saline, low dose, medium dose and high dose groups. DS was given between weeks 15 and 21 of gestation. Total numbers of spermatogonia and Sertoli cells were counted in the testes of 7-day-old male rats using the physical disector method. By the end of the study, the total number of Sertoli cells was decreased significantly in a dose dependent manner in the medium and high dose groups compared to controls. No significant differences were found in the total number of spermatogonia in the control, saline and low dose DS groups. Medium and high dose DS administration reduced the total number of spermatogonia compared to other groups. We suggest that prenatal administration of DS can cause deleterious effects on the testis development, especially in high doses. 相似文献