Occurrence of Horizontal Gene Transfer of PIB-type ATPase Genes among Bacteria Isolated from the Uranium Rich Deposit of Domiasiat in North East India

Uranium (U) tolerant aerobic heterotrophs were isolated from the subsurface soils of one of the pre-mined U-rich deposits at Domiasiat located in the north-eastern part of India. On screening of genomic DNA from 62 isolates exhibiting superior U and heavy metal tolerance, 32 isolates were found to be positive for P_IB-type ATPase genes. Phylogenetic incongruence and anomalous DNA base compositions revealed the acquisition of P_IB-type ATPase genes by six isolates through horizontal gene transfer (HGT). Three of these instances of HGT appeared to have occurred at inter-phylum level and the other three instances indicated to have taken place at intra-phylum level. This study provides an insight into one of the possible survival strategies that bacteria might employ to adapt to environments rich in uranium and heavy metals.     

Spinal ascending projections to the nucleus tractus spinalis nervi trigemini of the dog

Seven dogs were subjected 30 min to ligation of the thoracic aorta and were then kept alive 6-7 days after the ligature had been removed. Their spinal cord and brain stem were treated by the Nauta-Gygax method and the extent and appearance of preterminal and terminal degeneration of certain ascending spinal systems were analysed. In the medulla oblongata region, marked degenerating fibres from the lower thoracic and lumbosacral cord segments were found in the nucleus tractus spinalis nervi trigemini. Preterminal and terminal degenerating fibres were visualized in the caudal part of the trigeminal nuclear complex. Comparison with the literature showed these to be previously unknown projections with a relationship to the nucleus tractus spinalis nervi trigemini.     

Visualization of multiple protein bands on the same nitrocellulose membrane by double immunoblotting

A method has been developed which allows the simultaneous immunodetection of more than one type of protein on the same nitrocellulose membrane. This procedure does not require special labeling of samples or elution of antibodies from the membrane as do the alternatives cited in the literature (1,2). Proteins are separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electrophoretically transferred to the membrane before specific immunostaining with either peroxidase/4-chloro-1-naphthol or immunogold/silver staining. Antigen identity is visually determined by the formation of different-colored precipitates on the membrane. This innovation in protein blotting offers a savings in time and reagents as well as permitting identification of closely spaced bands with certainty.     

Cytochemical localization of 5′-nucleotidase in the enteric ganglia and in smooth muscle cells of the guinea-pig

Brain Cell Biology - Cytochemical techniques were used to study the localization of 5′-nucleotidase in the enteric ganglia and in smooth muscle cells of the guinea-pig ileum, iris and vas...     

Lipid-bound sugars in malignant human breast tumors

Microsomal preparations from malignant human breast tumors catalyzed the transfer of mannose and glucose from GDP-[14C]-Man and UDP-[14C]-Glc into lipid-linked sugars and glycoprotein-like substances. As judged by several criteria the obtained lipid-linked monosaccharides behaved as dolichyl phosphate mannose and dolichyl phosphate glucose whereas lipid-linked oligosaccharides behaved as polyprenyl diphosphate derivatives. The optimum conditions for mannosyl- and glucosyl-transfer reactions and the effect of dolichyl phosphate, detergent and EDTA on incubation mixture were described.     

Mutations inside but not outside the peptide binding cleft of the H-2 Ld molecule affects CTL recognition and binding of the nucleoprotein peptide from the lymphocytic chroriomeningitis

In order to investigate the role of residues inside and outside the peptide binding cleft of the L² molecule in peptide presentation to cytotoxic T lymphocytes (CTL), we constructed a series of point mutations in the L ^d gene. We determined the effects of the mutations in the L^d molecule on the binding and recognition of an L^d-restricted CTL epitope derived from the nucleoprotein (NP) of the lymphocytic phoriomeningitis virus (LCMV). Each of the mutations within the L^d peptide binding cleft resulted in a complete loss of CTL recognition. Addition of the LCMV NP peptide to cells expressing these mutants did not increase surface L^d expression, suggesting that the mutations altered peptide binding. Mutations involving pockets D and E within the cleft affected LCMV peptide binding and recognition as drastically as those in pocket B, which was predicted to interact with a main anchor residue of the peptide. In striking contrast, the mutations located outside the cleft did not change either recognition or binding. These results demonstrate that the L^d residues in the peptide binding cleft are the main determinants dictating LCMV NP peptide binding, and that the residues in each of the pockets within the cleft play a role in this interaction. Surprisingly, one mutation outside the peptide binding cleft, T92S, abrogated CTL lysis of target cells treated with the LCMV NP peptide, but not virus-infected cells. These data show that this mutation selectively altered the presentation of the LCMV NP peptide introduced to the cell exogenously, but not endogenously. This implies that the pathway by which peptides associate with class I molecules within the cell differs from that of exogenous peptide binding.     

Effect of the cumulus on in vitro fertilization of bovine matured oocytes

The effect of the cumulus on in vitro fertilization in bovines was examined. Follicular oocytes were cultured in medium 199 plus OCS and extra granulosa cells. Frozen-thawed bovine spermatozoa was separated by the swim-up technique, suspended in Talp medium and capacitated with heparin. Fresh sheep and goat semen was incubated for 4 h at room temperature, washed and spermatozoa were then suspended in Talp medium and capacitated by incubation at 38.5 °C and 5% CO₂ in air and heparin.

In experiment 1, cumulus-enclosed oocytes, denuded oocytes and denuded oocytes plus additional cumulus cells were incubated with a reduced concentration of bovine spermatozoa for 8 or 18 h. In Experiment 2, cumulus enclosed and denuded oocytes were incubated with bovine spermatozoa for 4, 6, 8 and 18 h using a sperm concentration adjusted to secure high fertilization rates. In Experiment 3, cumulus-enclosed and denuded bovine oocytes were incubated with either sheep or goat spermatozoa for 18 h. Fertilization rates were then calculated and compared statistically. The results showed that 1) the cumulus improved the fertilization rate only when cumulus cells were associated with the oocytes 2) the timing of sperm penetration was not modified by the cumulus and started at 4 h after sperm incubation and 3) the presence of the cumulus improved the heterologous fertilization rate only when sheep spermatozoa were used. The results suggest that the cumulus improves fertilization rate by providing a capacitation-inducing mechanism and by facilitating the interaction between capacitated spermatozoa and the zona pellucida surface.     

Litter and soil biodiversity jointly drive ecosystem functions

The decomposition of litter and the supply of nutrients into and from the soil are two fundamental processes through which the above- and belowground world interact. Microbial biodiversity, and especially that of decomposers, plays a key role in these processes by helping litter decomposition. Yet the relative contribution of litter diversity and soil biodiversity in supporting multiple ecosystem services remains virtually unknown. Here we conducted a mesocosm experiment where leaf litter and soil biodiversity were manipulated to investigate their influence on plant productivity, litter decomposition, soil respiration, and enzymatic activity in the littersphere. We showed that both leaf litter diversity and soil microbial diversity (richness and community composition) independently contributed to explain multiple ecosystem functions. Fungal saprobes community composition was especially important for supporting ecosystem multifunctionality (EMF), plant production, litter decomposition, and activity of soil phosphatase when compared with bacteria or other fungal functional groups and litter species richness. Moreover, leaf litter diversity and soil microbial diversity exerted previously undescribed and significantly interactive effects on EMF and multiple individual ecosystem functions, such as litter decomposition and plant production. Together, our work provides experimental evidence supporting the independent and interactive roles of litter and belowground soil biodiversity to maintain ecosystem functions and multiple services.     

Sex determination and optimal development in the Moorish gecko,Tarentola mauritanica

Under temperature sex determination (TSD), sex is determined by temperature during embryonic development. Depending on ecological and physiological traits and plasticity, TSD species may face demographic collapse due to climate change. In this context, asymmetry in bilateral organisms can be used as a proxy for developmental instability and, therefore, deviations from optimal incubation conditions. Using Tarentola mauritanica gecko as a model, this study aimed first to confirm TSD, its pattern and pivotal temperature, and second to assess the local adaptation of TSD and variation of asymmetry patterns across four populations under different thermal regimes. Eggs were incubated at different temperatures, and hatchlings were sexed and measured. The number of lamellae was counted in adults and hatchlings. Results were compatible with a TSD pattern with males generated at low and females at high incubation temperatures. Estimated pivotal temperature coincided with the temperature producing lower embryonic mortality, evidencing selection towards balanced sex ratios. The temperature of oviposition was conservatively selected by gravid females. Asymmetry patterns found were likely related to nest temperature fluctuations. Overall, the rigidity of TSD may compromise reproductive success, and demographic stability in this species in case thermal nest choice becomes constrained by climate change.