Effects of temperature on protein structure and dynamics: X-ray crystallographic studies of the protein ribonuclease-A at nine different temperatures from 98 to 320 K.

Structures using X-ray diffraction data collected to 1.5-A resolution have been determined for the protein ribonuclease-A at nine different temperatures ranging from 98 to 320 K. It is determined that the protein molecule expands slightly (0.4% per 100 K) with increasing temperature and that this expansion is linear. The expansion is due primarily to subtle repacking of the molecule, with exposed and mobile loop regions exhibiting the largest movements. Individual atomic Debye-Waller factors exhibit predominantly biphasic behavior, with a small positive slope at low temperatures and a larger positive slope at higher temperatures. The break in this curve occurs at a characteristic temperature of 180-200 K, perhaps indicative of fundamental changes in the dynamical structure of the surrounding protein solvent. The distribution of protein Debye-Waller factors is observed to broaden as well as shift to higher values as the temperature is increased.     

A human cDNA encoding the small subunit of RNA polymerase II transcription factor SIII

A full-length cDNA encoding a human homolog of the 15-kDa subunit (p15) of RNA polymerase II elongation factor SIII was isolated and sequenced. Comparison of the open reading frames of the human p15 cDNA and the previously characterized rat p15 cDNA [Garrett et al., Proc. Natl. Acad. Sci. USA 91 (1994) 5237-5241] indicates that they encode identical proteins and are 93% conserved in nucleotide sequence.     

Mitochondrial haplogroup N1a phylogeography,with implication to the origin of European farmers

Background  

Tracing the genetic origin of central European farmer N1a lineages can provide a unique opportunity to assess the patterns of the farming technology spread into central Europe in the human prehistory. Here, we have chosen twelve N1a samples from modern populations which are most similar with the farmer N1a types and performed the complete mitochondrial DNA genome sequencing analysis. To assess the genetic and phylogeographic relationship, we performed a detailed survey of modern published N1a types from Eurasian and African populations.     

A Comprehensive Review of Animal Models for Coronaviruses: SARS-CoV-2, SARS-CoV,and MERS-CoV

The recent outbreak of coronavirus disease(COVID-19) caused by the novel severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) has already affected a large population of the world. SARS-CoV-2 belongs to the same family of severe acute respiratory syndrome coronavirus(SARS-CoV) and Middle East respiratory syndrome coronavirus(MERSCoV). COVID-19 has a complex pathology involving severe acute respiratory infection, hyper-immune response, and coagulopathy. At present, there is no therapeutic drug or vaccine approved for the disease. There is an urgent need for an ideal animal model that can reflect clinical symptoms and underlying etiopathogenesis similar to COVID-19 patients which can be further used for evaluation of underlying mechanisms, potential vaccines, and therapeutic strategies. The current review provides a paramount insight into the available animal models of SARS-CoV-2, SARS-CoV, and MERS-CoV for the management of the diseases.     

Survivability of parthenogenetic embryos following in vivo transfer in naturally synchronized Capra hircus

The present study was conducted to see the in vivo developmental potency of caprine parthenogenetic embryos generated in a modified way. The good quality caprine oocytes were matured in presence of cytochalasin B (CCB) and then activated by 7% ethanol followed by 2 mM 6-dimethyl amino purine (6-DMAP) and embryo development was recorded. Early stage parthenogenetic embryos (two to four cells) were surgically transferred in recipients (10). The pregnancy diagnosis was done by nonreturn to oestrus, ultrasonography (USG), and progesterone estimation. The levels of progesterone were above normal values (1 ng/ml) of pregnancy and fall below the level of pregnancy just before retuned to oestrus. Progesterone profile revealed that out of ten recipients (G1–G10), four goats (G1, G2, G3, and G5) returned to oestrus after 43?±?7.29 (Mean?±?SE) d of embryo transfer and six goats (G4, G6, G7, G8, G9, and G10) did not return to cycle even after 70 d of embryo transfer. In three recipients (G4, G5, and G6), the USG on day 40 revealed that there was fluid filled uterine body with solid fetus-like structure. These might be dead fetus and had started resorption. The progesterone profile also corroborated the assumption of pregnancy in these animals. Authors believe that this may be the first report on in vivo diploid parthenogenetic embryo development in caprine species.     

Snowflake Vitreoretinal Degeneration (SVD) Mutation R162W Provides New Insights into Kir7.1 Ion Channel Structure and Function

Snowflake Vitreoretinal Degeneration (SVD) is associated with the R162W mutation of the Kir7.1 inwardly-rectifying potassium channel. Kir7.1 is found at the apical membrane of Retinal Pigment Epithelial (RPE) cells, adjacent to the photoreceptor neurons. The SVD phenotype ranges from RPE degeneration to an abnormal b-wave to a liquid vitreous. We sought to determine how this mutation alters the structure and function of the human Kir7.1 channel. In this study, we expressed a Kir7.1 construct with the R162W mutation in CHO cells to evaluate function of the ion channel. Compared to the wild-type protein, the mutant protein exhibited a non-functional Kir channel that resulted in depolarization of the resting membrane potential. Upon co-expression with wild-type Kir7.1, R162W mutant showed a reduction of I_Kir7.1 and positive shift in ‘0’ current potential. Homology modeling based on the structure of a bacterial Kir channel protein suggested that the effect of R162W mutation is a result of loss of hydrogen bonding by the regulatory lipid binding domain of the cytoplasmic structure.