Using RT-PCR and glutathione level to study the effect of follicular fluid on in vitro maturation and gene expression of sheep oocytes

The aim of this study is to evaluate the effect of sheep follicular fluid (SFF) supplementation of the in vitro maturation (IVM) media of sheep oocytes on the resumption of meiosis, glutathione (GSH) level, and expression of apoptosis (Bax, Bcl-2) as well as heat shock protein beta-1 (HSPB1) genes. Sheep ovaries were collected from the central slaughterhouse of Riyadh city, KSA. Oocytes were aspirated from 3 to 8 mm follicles. Sheep oocytes were cultured in maturation medium with different concentrations of sheep follicular fluid: 0% (control), 10%, 20% and 40% for 24 h. The results indicated that the maturation rate of oocytes was significantly (p ≤ .05) decreased in 40% SFF (36.87%) versus the control (61.3%), 10% SFF (63.95%) and 20% SFF (64.08%). The supplementation of the IVM medium with 10% SFF induced an intra-oocyte GSH concentration that was significantly higher than in sheep oocytes cultured with 20% and 40% SFF and similar to the GSH content in oocytes cultured without SFF. Real-time polymerase chain reaction analysis of gene expression revealed no significant differences in the Bax and HSPB1 genes between the control and 10% SFF, whereas they were significantly higher in 40% FF (p ≤ .05) compared to the control. The expression of Bax:Bcl-2 was significantly higher in 20% and 40% SFF compared to the control group. In conclusion, the addition of SFF to the IVM culture of sheep oocytes is recommended to support nuclear maturation and increase oocyte competence.     

Functional divergence of the circadian clock proteins in prokaryotes

Cyanobacteria are only prokaryotes known so far to have a circadian system. It may be based either on two (kaiB and kaiC) or three (kaiA, kaiB and kaiC) circadian genes. The homologs of two circadian proteins, KaiB and KaiC, form four major subfamilies (K1–K4) and also occur in some other prokaryotes. Using the likelihood-ratio tests, we studied a rate shift at the functional divergence of the proteins from the different subfamilies. It appears that only two of the subfamilies (K1 and K2) perform circadian functions. We identified in total 92 sites that have significantly different rates of evolution between the clades K1/K2 and K3/K4; 67 sites (15 in KaiB and 52 in KaiC) been evolving significantly slower in K1/K2 than the overall average for the entire sequence. Many critical sites are located in the identified functionally important motifs and regions, e.g. one of the Walker’s motif As, DXXG motif, and two KaiA-binding domains of KaiC. There are also 36 sites (~5%) with rate shift between K1 and K2. The rate shift at these sites may be related to the interaction with KaiA. Rate shift analyses have identified residues whose manipulation in the Kai proteins may lead to better understanding of their functions in the two different types of the cyanobacterial circadian system.     

An unstable gene controlling developmental variegation in okra (Abelmoschus esculentus (L.) Moench)

Summary Genetic studies on radiation-induced chlorina and variegated mutants of okra (Abelmoschus esculentus (L.) Moench) revealed the existence of an unstable gene. The normal green color of the leaves is controlled by duplicate genes C₁ and C₂, either of which produces the green colour. The chlorina plants are C ₁ C ₁ C ₂ C ₂. The allele c ₁ ^v is dominant to both C ₁ and C ₂ but is unstable. The homozygote c ₁ ^v c ₁ ^v c ₂ c ₂ is a normal green while the heterozygote c _i ^v c ₁ c ₂ c ₂ has a variegated phenotype as a result of the mutation of c ₁ ^v to c ₁ during development. In green plants with a c ₁ ^v c{sh1/v}c ₂ c ₂ genotype, the autonomous mutation of one of the c ₁ ^v alleles to c ₁ may take place at the pre-meiotic stage. In the variegated genotype (c ₁ ^v c ₁ c ₂ c ₂), the mutation of c ₁ to c ₁ ^v may take place in early ontogeny, thus producing green plants. The allele C ₁, when associated with c ₁ ^v in a heterozygous condition, mutates to c ₁ at the pre-meiotic stage even in the presence of the allele C ₂.     

New World Monkeys and Color

The visual worlds of most primates are rich with potential color signals, and many representatives of the order have evolved the biological mechanisms that allow them to exploit these sources of information. Unlike the catarrhines, platyrrhines typically have sex-linked polymorphic color vision that provides individuals with any of several distinct types of color vision, including both trichromatic and dichromatic variants. In recent years, this polymorphism has been the target of an expanding range of research efforts. As a result, researchers now reasonably understand the proximate biology underlying the polymorphisms, and a number of ideas have emerged as to their evolution. Progress has also been made in illuminating how color vision capacities may be related to the particular visual tasks that New World monkeys face.