Predicted class-I aminoacyl tRNA synthetase-like proteins in non-ribosomal peptide synthesis

Background  

Recent studies point to a great diversity of non-ribosomal peptide synthesis systems with major roles in amino acid and co-factor biosynthesis, secondary metabolism, and post-translational modifications of proteins by peptide tags. The least studied of these systems are those utilizing tRNAs or aminoacyl-tRNA synthetases (AAtRS) in non-ribosomal peptide ligation.     

T Cell Factor-1 Controls the Lifetime of CD4+ CD8+ Thymocytes In Vivo and Distal T Cell Receptor α-Chain Rearrangement Required for NKT Cell Development

Natural killer T (NKT) cells are a component of innate and adaptive immune systems implicated in immune, autoimmune responses and in the control of obesity and cancer. NKT cells develop from common CD4+ CD8+ double positive (DP) thymocyte precursors after the rearrangement and expression of T cell receptor (TCR) Vα14-Jα18 gene. Temporal regulation and late appearance of Vα14-Jα18 rearrangement in immature DP thymocytes has been demonstrated. However, the precise control of lifetime of DP thymocytes in vivo that enables distal rearrangements remains incompletely defined. Here we demonstrate that T cell factor (TCF)-1, encoded by the Tcf7 gene, is critical for the extended lifetime of DP thymocytes. TCF-1-deficient DP thymocytes fail to undergo TCR Vα14-Jα18 rearrangement and produce significantly fewer NKT cells. Ectopic expression of Bcl-x_L permits Vα14-Jα18 rearrangement and rescues NKT cell development. We report that TCF-1 regulates expression of RORγt, which regulates DP thymocyte survival by controlling expression of Bcl-x_L. We posit that TCF-1 along with its cofactors controls the lifetime of DP thymocytes in vivo.     

RAB-6.1 and RAB-6.2 Promote Retrograde Transport in C. elegans

Retrograde transport is a critical mechanism for recycling certain membrane cargo. Following endocytosis from the plasma membrane, retrograde cargo is moved from early endosomes to Golgi followed by transport (recycling) back to the plasma membrane. The complete molecular and cellular mechanisms of retrograde transport remain unclear. The small GTPase RAB-6.2 mediates the retrograde recycling of the AMPA-type glutamate receptor (AMPAR) subunit GLR-1 in C. elegans neurons. Here we show that RAB-6.2 and a close paralog, RAB-6.1, together regulate retrograde transport in both neurons and non-neuronal tissue. Mutants for rab-6.1 or rab-6.2 fail to recycle GLR-1 receptors, resulting in GLR-1 turnover and behavioral defects indicative of diminished GLR-1 function. Loss of both rab-6.1 and rab-6.2 results in an additive effect on GLR-1 retrograde recycling, indicating that these two C. elegans Rab6 isoforms have overlapping functions. MIG-14 (Wntless) protein, which undergoes retrograde recycling, undergoes a similar degradation in intestinal epithelia in both rab-6.1 and rab-6.2 mutants, suggesting a broader role for these proteins in retrograde transport. Surprisingly, MIG-14 is localized to separate, spatially segregated endosomal compartments in rab-6.1 mutants compared to rab-6.2 mutants. Our results indicate that RAB-6.1 and RAB-6.2 have partially redundant functions in overall retrograde transport, but also have their own unique cellular- and subcellular functions.     

The prokaryotic antecedents of the ubiquitin-signaling system and the early evolution of ubiquitin-like β-grasp domains

Background  

Ubiquitin (Ub)-mediated signaling is one of the hallmarks of all eukaryotes. Prokaryotic homologs of Ub (ThiS and MoaD) and E1 ligases have been studied in relation to sulfur incorporation reactions in thiamine and molybdenum/tungsten cofactor biosynthesis. However, there is no evidence for entire protein modification systems with Ub-like proteins and deconjugation by deubiquitinating enzymes in prokaryotes. Hence, the evolutionary assembly of the eukaryotic Ub-signaling apparatus remains unclear.     

Cephalometric comparison of Indian and English facial profiles

Cephalometric measurements on 50 English and 50 Indian adults, equally divided as regards sex, were compared for sex and group difference. Evaluation of the average measurements indicated that the female facial size was generally smaller than the male: the Indian face was not prognathic but was smaller and had smaller facial and gonial angles, and the lower incisor was proclined as compared with the English face. A statistical analysis using the Generalized T²-test and Discriminatory Analysis brought out these differences very convincingly, and with nearly 80% accuracy it was possible to classify the individuals to their correct sex and Indian or English group. Incidentally it was found that the Sella Nasion Plane, Maxillary Plane and Frankfort Plane are all equally suitable for assessing the upper incisor inclination.     

In vitro study of transgenic tobacco expressing Arabidopsis wild type and mutant acetohydroxyacid synthase genes

Summary Genes coding for the enzyme acetohydroxyacid synthase, often referred to as acetolactate synthase (AHAS, ALS; EC 4.1.3.18), from wild type Arabidopsis thaliana and a sulfonylurea-resistant mutant line GH50 (csrl-1; Haughn et al. 1988) were introduced in Nicotiana tabacum. Both genes were expressed at high levels with the 35S promoter. The csrl-1 gene conferred high levels of resistance to chlorsulfuron whereas the wild type gene did not. As selectable markers, chimaeric AHAS genes yielded transgenic plants on chlorsulfuron but at much lower efficiencies than with a chimaeric neomycin phosphotransferase gene on kanamycin (Sanders et al. 1987). Shoot differentiation from leaf discs was delayed on chlorsulfuron by 4–6 weeks. This study indicated a role for mutant AHAS genes in the genetic manipulation of herbicide resistance in transgenic plants but as selectable markers for plant cells undergoing differentiation no advantage over other genes was perceived.     

DNA cassettes containing the origin of transfer (oriT) of two broad-host-range transfer systems.

Plasmid constructs are described that carry retrievable DNA cassettes containing the origin of transfer region (oriT) from two broad-host-range plasmids. Restriction of these high copy number plasmids with any one of a variety of enzymes yields a linear DNA fragment of convenient size containing the oriT region of either pCUI or RK2. This DNA can be ligated into any vector or recombinant plasmid containing a compatible enzyme site and can be easily identified by size on an agarose gel. Any plasmid can therefore be mobilized using a number of helper strains or conjugative plasmids derived from the parental plasmids. In addition, the cassettes can be used for a variety of genetic manipulations including "selectable" linker mutagenesis.     

Bimodal oxygen uptake in a freshwater air-breathing fish,Notopterus chitala

Measurements of bimodal oxygen uptake have been made in a freshwater air-breathing fish,Notopterus chitala at 29.0±1(S.D.)°C. xhe mean oxygen uptake from continuously flowing water without any access to air, was found to be 3.58±0.37 (S.E.) ml O₂ · h^?1 and 56.84+4.29 (S.E.) ml O₂ · kg^?1 · h^?1 for a fish weighing 66.92 + 11.27 (S.E.) g body weight. In still water with access to air, the mean oxygen uptake through the gills were recorded to be 2.49 ± 0.31 (S.E.) ml O₂ · h^?1 and 38.78 ± 1.92 (S.E.) ml O₂ · kg^?1 · h^?1 and through the accessory respiratory organs (swim-bladder) 6.04±0.87 (S.E.) ml O₂ · h^?1 and 92.32±2.91 (S.E.) ml O₂ · kg^?1 · h^?1 for a fish averaging 66.92±11.27 (S.E.) g. Out of the total oxygen uptake (131.10 ml O₂ · kg^?1 · h^?1), about 70% was obtained through the aerial route and the remainder 30% through the gills.