Nuclear structure and chromosome segregation in Drosophila male meiosis depend on the ubiquitin ligase dTopors

In many organisms, homolog pairing and synapsis at meiotic prophase depend on interactions between chromosomes and the nuclear membrane. Male Drosophila lack synapsis, but nonetheless, their chromosomes closely associate with the nuclear periphery at prophase I. To explore the functional significance of this association, we characterize mutations in nuclear blebber (nbl), a gene required for both spermatocyte nuclear shape and meiotic chromosome transmission. We demonstrate that nbl corresponds to dtopors, the Drosophila homolog of the mammalian dual ubiquitin/small ubiquitin-related modifier (SUMO) ligase Topors. We show that mutations in dtopors cause abnormalities in lamin localizations, centriole separation, and prophase I chromatin condensation and also cause anaphase I bridges that likely result from unresolved homolog connections. Bridge formation does not require mod(mdg4) in meiosis, suggesting that bridges do not result from misregulation of the male homolog conjunction complex. At the ultrastructural level, we observe disruption of nuclear shape, an uneven perinuclear space, and excess membranous structures. We show that dTopors localizes to the nuclear lamina at prophase, and also transiently to intranuclear foci. As a role of dtopors at gypsy insulator has been reported, we also asked whether these new alleles affected expression of the gypsy-induced mutation ct(6) and found that it was unaltered in dtopors homozygotes. Our results indicate that dTopors is required for germline nuclear structure and meiotic chromosome segregation, but in contrast, is not necessary for gypsy insulator function. We suggest that dtopors plays a structural role in spermatocyte lamina that is critical for multiple aspects of meiotic chromosome transmission.     

Response of Java citronella (Cymbopogon winterianus Jowitt) to toxic heavy metal cadmium.

Cadmium at 200 mg kg-1 soil and above concentrations was fatal as growth was inhibited ultimately leading to death of Java citronella (Cymbopogon winterianus Jowitt.). The surviving plants at 50 and 100 mg kg-1 treatments also exhibited pronounced retardation of growth and biomass yield. There was considerable reduction in the level of essential oil in herbage and oil quality deteriorated. Cadmium accumulation profile showed that highest accumulation was in root, followed by stem, leaf sheath and leaf. Very high accumulation in root for higher doses appeared to be the reason for fatality.     

Flood plain wetland fisheries of India: with special reference to impact of climate change

Floodplain wetlands of India are biologically rich sensitive ecosystem that support unique aquatic biodiversity and play vital role in providing livelihood and nutritional security to a large section of the population of the country. Besides contributing to the environmental sustainability through Carbon sequestration, flood plain wetlands also serve as source for harvesting flood and rain water. Covering around 5.5 Lakh ha area, the flood plain wetlands of India are one of the major sources for fish production of the country, offering vast potential for capture as well as culture based fisheries. Degradation and shrinkage of the floodplain wetlands have been recorded due to several natural and anthropogenic reasons. In addition to that, the change in the climatic condition may have a far more devastating impact on these natural resources. Substantial change in climate with increasing temperature trend (0.60 °C during last 112 years) as well as changing pattern and intensity of rainfall have been reported in India. It is projected that extreme climate changes may have profound impact on wetlands, mediated through several direct or indirect pathways. Attention is urgently required at different levels for conservation and revamping of these resources along with coping up and mitigation strategies to address the impending challenges. However, there is dearth of scientific information specific to the flood plain wetlands of India. This paper reviews the present status and importance of the flood plain wetlands of India with special reference to impact of climate change along with coping-up and mitigation measures.     

Piroxicam confer neuroprotection in Cerebral Ischemia by inhibiting Cyclooxygenases,Acid- Sensing Ion Channel-1a and Aquaporin-4: an in silico comparison with Aspirin and Nimesulide

Cerebral ischemia (CI), caused by the deprivation of oxygen and glucose to the brain, is the leading cause of permanent disability.Neuronal demise in CI has been linked to several pathways which include cyclooxygenases (COX) − mediated production ofprostaglandins (PGs) and subsequently reactive oxygen species (ROS), aquaporin-4 (AQ-4) − mediated brain edema and acidsensingion channel-1a (ASIC-1a) − mediated acidotoxicity, matrix remodeling, in addition to others. Several non-steroidal antiinflammatorydrugs (NSAIDs) are presently in use to prevent these pathways. However, owing to the large number of processesinvolved, there is high drug load. So, identifying drugs with multimodal role has always been a frequently sought venture. Thepresent in silico study has been performed to find out the relative efficacy of three different NSAIDs (Piroxicam, Aspirin andNimesulide) in preventing neurodegeneration in CI, with respect to their inhibitory potential on COXs, AQ-4 and ASIC-1a. We findthat piroxicam is the most potent inhibitor of these receptors as compared to the NSAIDs under investigation. Since piroxicam hasalready been reported to inhibit N-methyl-D-aspartate (NMDA) receptor and matrix metalloproteinases (MMPs), which are alsolinked to CI-induced neurodegeneration, we hereby propose piroxicam to be a gold-standard drug in preventingneurodegeneration in CI.     

Hypoxia and its effect on the cellular system

Eukaryotic cells utilize oxygen for different functions of cell organelles owing to cellular survival. A balanced oxygen homeostasis is an essential requirement to maintain the regulation of normal cellular systems. Any changes in the oxygen level are stressful and can alter the expression of different homeostasis regulatory genes and proteins. Lack of oxygen or hypoxia results in oxidative stress and formation of hypoxia inducible factors (HIF) and reactive oxygen species (ROS). Substantial cellular damages due to hypoxia have been reported to play a major role in various pathological conditions. There are different studies which demonstrated that the functions of cellular system are disrupted by hypoxia. Currently, study on cellular effects following hypoxia is an important field of research as it not only helps to decipher different signaling pathway modulation, but also helps to explore novel therapeutic strategies. On the basis of the beneficial effect of hypoxia preconditioning of cellular organelles, many therapeutic investigations are ongoing as a promising disease management strategy in near future. Hence, the present review discusses about the effects of hypoxia on different cellular organelles, mechanisms and their involvement in the progression of different diseases.     

Conformation of double-stranded polydeoxynucleotides in solution by proton two-dimensional nuclear Overhauser enhancement spectroscopy

Proton 2D-NOE spectroscopy has been used to investigate the three-dimensional conformations of several sonicated polydeoxynucleotides in solution. The observed pattern of cross peaks indicate that poly(dA-dT) · poly(dA-dT) in all salt concentrations studied (up to 6.6M CsF), and poly(dG-m⁵dC) · poly(dG-m⁵dC) in low salt (0.1M NaCl) are righthanded B-structures. Poly(dG-m⁵dC) · poly(dG-m⁵dC) in Mg²⁺ (3 mM) solution exhibits a pattern characteristic of the left-handed Z-form. These results for poly(dA-dT) · poly(dA-dT) are in contrast to suggestions that this copolymer exists as a left-handed form, either in low or high salt. We present pure absorption-mode 2D-NOE spectra that enable us to compare several distances and define the conformations of these polydeoxynucleotides in solution.     

Island scalp flap for superior forehead reconstruction

An island scalp fasciocutaneous flap, based on the posterior superficial temporal vessels, is described for single-stage reconstruction of full-thickness forehead and scalp defects. The hairline can be precisely determined and tailored to restore symmetry. By removing the hair-bearing dermis of the forehead portion of the flap and placing a full-thickness skin graft, aesthetic reconstitution of the forehead skin is achieved. This flap is especially useful when exposed calvarium limits other techniques.