Fine‐scale ecological and anthropogenic variables predict the habitat use and detectability of sloth bears in the Churia habitat of east Nepal

Once widespread throughout the tropical forests of the Indian Subcontinent, the sloth bears have suffered a rapid range collapse and local extirpations in the recent decades. A significant portion of their current distribution range is situated outside of the protected areas (PAs). These unprotected sloth bear populations are under tremendous human pressures, but little is known about the patterns and determinants of their occurrence in most of these regions. The situation is more prevalent in Nepal where virtually no systematic information is available for sloth bears living outside of the PAs. We undertook a spatially replicated sign survey‐based single‐season occupancy study intending to overcome this information gap for the sloth bear populations residing in the Trijuga forest of southeast Nepal. Sloth bear sign detection histories and field‐based covariates data were collected between 2 October and 3 December 2020 at the 74 randomly chosen 4‐km² grid cells. From our results, the model‐averaged site use probability (ψ ± SE) was estimated to be 0.432 ± 0.039, which is a 13% increase from the naïve estimate (0.297) not accounting for imperfect detections of sloth bear signs. The presence of termite mound and the distance to the nearest water source were the most important variables affecting the habitat use probability of sloth bears. The average site‐level detectability (p ± SE) of sloth bear signs was estimated to be 0.195 ± 0.003 and was significantly determined by the index of human disturbances. We recommend considering the importance of fine‐scale ecological and anthropogenic factors in predicting the sloth bear‐habitat relationships across their range in the Churia habitat of Nepal, and more specifically in the unprotected areas.     

Synechococcus sp. PCC7942 Transformed with Escherichia coli bet Genes Produces Glycine Betaine from Choline and Acquires Resistance to Salt Stress

Synechococcus sp. PCC7942, a fresh water cyanobacterium, was transformed by a shuttle plasmid that contains a 9-kb fragment encoding the Escherichia coli bet gene cluster, i.e. betA (choline dehydrogenase), betB (betaine aldehyde dehydrogenase), betI (a putative regulatory protein), and betT (the choline transport system). The expression of these genes was demonstrated in the cyanobacterial cells (bet-containing cells) by northern blot analysis, as well as by the detection of glycine betaine by 1H nuclear magnetic resonance in cells supplemented with choline. Endogenous choline was not detected in either control or bet-containing cells. Both control and bet-containing cyanobacterial cells were found to import choline in an energy-dependent process, although this import was restricted only to bet-containing cells in conditions of salt stress. Glycine betaine was found to accumulate to a concentration of 45 mM in bet-containing cyanobacterial cells, and this resulted in a stabilization of the photosynthetic activities of photosystems I and II, higher phycobilisome contents, and general protective effects against salt stress when compared to control cells. The growth of bet-containing cells was much faster in the presence of 0.375 M NaCl than that of control cells, indicating that the transformant acquired resistance to salt stress.     

Ectopic F0F1 ATP synthase contains both nuclear and mitochondrially-encoded subunits

Over the past few years, several reports have described the presence of F₀F₁ ATP synthase subunits at the surface of hepatocytes, where the hydrolytic activity of F₁ sector faces outside and triggers HDL endocytosis. An intriguing question is whether the ectopic enzyme has same subunit composition and molecular mass as that of the mitochondrial ATP synthase. Also due to the polar nature of hepatocytes, the enzyme may be localized to a particular cell boundary. Using different methods to prepare rat liver plasma membranes, which have been subjected to digitonin extraction, hr CN PAGE, immunoblotting, and mass spectrometry analysis, we demonstrate the presence of ecto-F₀F₁ complexes which have a similar molecular weight to the monomeric form of the mitochondrial complexes, containing both nuclear and mitochondrially-encoded subunits. This finding makes it unlikely that the enzyme assembles on the plasma membranes, but suggest it to be transported whole after being assembled in mitochondria by still unknown pathways. Moreover, the plasma membrane preparation enriched in basolateral proteins contains much higher amounts of complete and active F₀F₁ complexes, consistent with their specific function to modulate the HDL uptake on hepatocyte surface.     

Toxicity of chromium and tin toAnabaena doliolum Interaction with bivalent cations

Summary The toxicity of chromium and tin on growth, photosynthetic carbon-fixation, oxygen evolution, heterocyst differentiation and nitrogenase activity ofAnabaena doliolum and its interaction with bivalent cations has been studied. Some interacting cations, viz. Ca²⁺, Mg²⁺ and Mn²⁺, substantially antagonised the toxic effects of chromium and tin with reference to growth, heterocyst differentiation and nitrogenase activity in the following hierarchal sequence: Ca²⁺ > Mg²⁺ > Mn²⁺. However, the sequence of hierarchy was Mg²⁺ > Ca²⁺ > Mn²⁺ for carbon fixation and Mn²⁺ > Mg²⁺ > Ca²⁺ for photosynthetic oxygen evolution. Synergistically inhibitory patterns were noticed for all the parameters, viz. growth,¹⁴CO₂ uptake, oxygen evolution, heterocyst differentiation and nitrogenase activity ofA. doliolum when Ni²⁺, Co²⁺ and Zn²⁺ were combined with the test metals in the growth medium. These cations followed the following sequence of synergistic inhibition: Ni²⁺ > Co²⁺ > Zn²⁺. Among all the interacting cations, Ca²⁺, Mg²⁺ and Mn²⁺ exhibited antagonistic effects which relieved the test cyanobacterium from metal toxicity. In contrast to this, Ni²⁺, CO²⁺ and Zn²⁺ showed synergistic inhibition which potentiating the toxicity of test metals in the N₂-fixing cyanobacteriumA. doliolum. It is evident from the present study that bivalent cations, viz. Ca²⁺, Mg²⁺, Mn²⁺, Ni²⁺, Co²⁺ and Zn²⁺, may appreciably regulate the toxicity of heavy metals in N₂-fixing cyanobacteria if present in aquatic media.     

Molecular mechanisms of Bartter syndrome caused by mutations in the BSND gene

Barttin, a gene product of BSND, was identified as a fourth gene responsible for Bartter syndrome. The co-expression of barttin with CLC-K chloride channels has been demonstrated to dramatically induce the expression of CLC-K current. However, it remains unknown how barttin interacts with CLC-K channels in mammalian cells and how the mutations of barttin lead to Bartter syndrome. In an attempt to clarify the effect of barttin expression on CLC-K2 cellular localization, we examined the expression of the CLC-K2 chloride channel and barttin, solely and in combination, in transient and stable expression systems in mammalian cells. In addition, we generated several stable cell lines expressing mutant barttins to clarify the consequence of the previously reported barttin mutations in Bartter syndrome. In immunocytochemistry, CLC-K2 was retained in the Golgi in the absence of barttin expression, but delivered to the plasma membrane when barttin was present. Barttin was coprecipitated with CLC-K2, suggesting a protein-protein interaction. Disease-causing mutant barttins, especially R8L, were retained intracellularly, but their binding ability to CLC-K2 was preserved. This led to a retention of CLC-K2 in intracellular organelles with barttin, and a loss of plasma membrane localization. The stability of the CLC-K2 protein was also markedly increased by coexpression with barttin. These results clarified that barttin determined cellular localization of CLC-K2 by protein-protein interaction. Thus, the mislocalization of CLC-K2 was identified as the molecular pathogenesis of Bartter syndrome by mutant barttins.     

Xanthoferrin,the α‐hydroxycarboxylate‐type siderophore of Xanthomonas campestris pv. campestris,is required for optimum virulence and growth inside cabbage

Xanthomonas campestris pv. campestris causes black rot, a serious disease of crucifers. Xanthomonads encode a siderophore biosynthesis and uptake gene cluster xss (Xanthomonas siderophore synthesis) involved in the production of a vibrioferrin‐type siderophore. However, little is known about the role of the siderophore in the iron uptake and virulence of X. campestris pv. campestris. In this study, we show that X. campestris pv. campestris produces an α‐hydroxycarboxylate‐type siderophore (named xanthoferrin), which is required for growth under low‐iron conditions and for optimum virulence. A mutation in the siderophore synthesis xssA gene causes deficiency in siderophore production and growth under low‐iron conditions. In contrast, the siderophore utilization ΔxsuA mutant is able to produce siderophore, but exhibits a defect in the utilization of the siderophore–iron complex. Our radiolabelled iron uptake studies confirm that the ΔxssA and ΔxsuA mutants exhibit defects in ferric iron (Fe³⁺) uptake. The ΔxssA mutant is able to utilize and transport the exogenous xanthoferrin–Fe³⁺ complex; in contrast, the siderophore utilization or uptake mutant ΔxsuA exhibits defects in siderophore uptake. Expression analysis of the xss operon using a chromosomal gusA fusion indicates that the xss operon is expressed during in planta growth and under low‐iron conditions. Furthermore, exogenous iron supplementation in cabbage leaves rescues the in planta growth deficiency of ΔxssA and ΔxsuA mutants. Our study reveals that the siderophore xanthoferrin is an important virulence factor of X. campestris pv. campestris which promotes in planta growth by the sequestration of Fe³⁺.     

A study on neuroinflammatory marker in brain areas of okadaic acid (ICV) induced memory impaired rats

AimsThe aim of the present study is to investigate the status of proinflammatory cytokine in the brain of intracerebroventricular (ICV) okadaic acid (OKA) induced memory impaired rat.Main methodsOKA (200 ng) intracerebroventricular (ICV) was administered in rats. Memory was assessed by Morris water maze test. Biochemical marker of neuroinflammation (TNF-α, IL-β), total nitrite, mRNA (RT PCR) and protein expression (WB) of iNOS and nNOS were estimated in rat brain areas.Key findingsOKA caused memory-impairment in rats with increased expression of proinflammatory cytokine TNF-α and IL-1β and total nitrite in brain regions hippocampus and cortex. The expression of mRNA and protein of iNOS was increased while; the expressions were decreased in case of nNOS. Pretreatment with antidementic drugs donepezil (5 mg/kg, p.o.) and memantine (10 mg/kg, p.o) for 13 days protected ICV OKA induced memory impairment and changes in level of TNF-α, IL-β, total nitrite and expressions of iNOS and nNOS in OKA treated rat.SignificanceThis study suggests that neuroinflammation may play a vital role in OKA induced memory impairment.     

The encapsulation technology in fruit plants—A review

Encapsulation technology is an exciting and rapidly growing area of biotechnological research. This has drawn tremendous attention in recent years because of its wide use in conservation and delivery of tissue cultured plants of commercial and economic importance. Production of synthetic seeds by encapsulating somatic embryos, shoot buds or any other meristmatic tissue helps in minimizing the cost of micropropagated plantlets for commercialization and final delivery. In most of fruit crops, seed propagation has not been successful because of heterozygosity of seeds, minute seed size, presence of reduced endosperm, low germination rate, and also some are having seedless varieties. Many species have desiccation-sensitive intermediate or recalcitrant seeds and can be stored for only a few weeks or months. Under these circumstances, increasing interest has been shown recently to use encapsulation technology for propagation and conservation. Many fruit plants are studied worldwide for breeding, genetic engineering, propagation, and pharmaceutical purposes. In this context, synthetic seeds would be more applicable in exchange of elite and axenic plant material between laboratories and extension centers due to small bead size and ease in handling. Due to these advantages, interest in using encapsulation technology has continuously been increasing in several fruit plant species. The purpose of this review is to focus upon current information on development of synthetic seeds in several fruit crops.