Temperature-dependent variation in toxicity of insecticides against Earias vitella (Lepidoptera: Noctuidae)

The toxicity of synthetic pyrethroids was found to be negatively correlated with temperature, whereas contrasting correlation was observed with the toxicity of organophosphorous compounds chlorpyriphos and quinalphos, which was most toxic at higher temperature. A similar phenomenon was observed in endosulfan at higher temperature and humidity combination. The insecticide molecules indoxacarb and spinosad were effective among the insecticides tested. Indoxacarb was effective at lower temperature, and spinosad was effective at all the temperature and relative humidity combinations with minor difference in LD50 values. During both the years, however, the levels of resistance were higher in second year compared with previous year.     

A SmD peptide induces better antibody responses to other proteins within the small nuclear ribonucleoprotein complex than to SmD protein via intermolecular epitope spreading

Autoantibody response against the small nuclear ribonucleoprotein (snRNP) complex is a characteristic feature of systemic lupus erythematosus. The current investigation was undertaken to determine whether activation of SmD-reactive T cells by synthetic peptides harboring T cell epitopes can initiate a B cell epitope spreading cascade within the snRNP complex. T cell epitopes on SmD were mapped in A/J mice and were localized to three regions on SmD, within aa 26-55, 52-69, and 86-115. Immunization with synthetic peptides SmD(31-45), SmD(52-66), and SmD(91-110) induced T and B cell responses to the peptides, with SmD(31-45) inducing the strongest response. However, only SmD(52-66) immunization induced T cells capable of reacting with SmD. Analysis of sera by immunoprecipitation assays showed that intermolecular B cell epitope spreading to U1RNA-associated A ribonucleoprotein and SmB was consistently observed only in the SmD(52-66)-immunized mice. Surprisingly, in these mice, Ab responses to SmD were at low levels and transient. In addition, the sera did not react with other regions on SmD, indicating a lack of intramolecular B cell epitope spreading within SmD. Our study demonstrates that T cell responses to dominant epitope on a protein within a multiantigenic complex are capable of inducing B cell responses to other proteins within the complex. This effect can happen without generating a good Ab response to the protein from which the T epitope was derived. Thus caution must be taken in the identification of Ags responsible for initiating autoimmune responses based solely on serological analysis of patients and animals with systemic autoimmune disorders.     

Identification of key structural determinants of the IntI1 integron integrase that influence attC x attI1 recombination efficiency

The integron platform codes for an integrase (IntI) from the tyrosine family of recombinases that mediates recombination between a proximal double-strand recombination site, attI and a single-strand target recombination site, attC. The attI site is only recognized by its cognate integrase, while the various tested attCs sites are recombined by several different IntI integrases. We have developed a genetic system to enrich and select mutants of IntI1 that provide a higher yield of recombination in order to identify key protein structural elements important for attC × attI1 recombination. We isolated mutants with higher activity on wild type and mutant attC sites. Interestingly, three out of four characterized IntI1 mutants selected on different substrates are mutants of the conserved aspartic acid in position 161. The IntI1 model we made based on the VchIntIA 3D structure suggests that substitution at this position, which plays a central role in multimer assembly, can increase or decrease the stability of the complex and accordingly influence the rate of attI × attC recombination versus attC × attC. These results suggest that there is a balance between the specificity of the protein and the protein/protein interactions in the recombination synapse.     

Nuclease Stn α from <Emphasis Type="Italic">Streptomyces thermonitrificans</Emphasis>: Characterization of the Associated Adenylic Acid Preferential Ribonuclease Activity

Nuclease Stn α from Streptomyces thermonitrificans hydrolyses DNA and RNA at the rate of approximately 10:l. The optimum pH and temperature for RNA hydrolysis were 7.0 and 45°C. The RNase activity of nuclease Stn α had neither an obligate requirement of metal ions nor was it activated in the presence of metal ions. The enzyme was inhibited by Zn²⁺, Mg²⁺, Co²⁺, and Ca²⁺; inorganic phosphate; pyrophosphate; NaCl; KCl; and metal chelators. It was stable at high concentrations of urea but susceptible to low concentrations of Sodium dodecyl sulfate and guanidine hydrochloride. The rates by which nuclease Stn α hydrolysed polyribonucleotides occurs in the order of poly A >> RNA >> poly U > poly G > poly C. The enzyme cleaved RNA to 3′ mononucleotides with preferential liberation of 3′AMP, indicating it to be an adenylic acid preferential endonuclease.     

Apoptosome dependent caspase-3 activation pathway is non-redundant and necessary for apoptosis in sympathetic neurons

Although sympathetic neurons are a well-studied model for neuronal apoptosis, the role of the apoptosome in activating caspases in these neurons remains debated. We find that the ability of sympathetic neurons to undergo apoptosis in response to nerve growth factor (NGF) deprivation is completely dependent on having an intact apoptosome pathway. Genetic deletion of Apaf-1, caspase-9, or caspase-3 prevents apoptosis after NGF deprivation, and importantly, allows these neurons to recover and survive long-term following readdition of NGF. The inability of caspase-3 deficient sympathetic neurons to undergo apoptosis is particularly striking, as apoptosis in dermal fibroblasts and cortical neurons proceeds even in the absence of caspase-3. Our results show that in contrast to dermal fibroblasts and cortical neurons, sympathetic neurons express no detectable levels of caspase-7. The strict requirement for an intact apoptosome, coupled with a lack of effector caspase redundancy, provides sympathetic neurons with a markedly increased control over their apoptotic pathway.     

Metalloids in plants: A systematic discussion beyond description

Metalloids represent a wide range of elements with intermediate physiochemical properties between metals and non-metals. Many of the metalloids, like boron, selenium, and silicon are known to be essential or quasi-essential for plant growth. In contrast, metalloids viz. arsenic and germanium are toxic to plant growth. The toxicity of metalloids largely depends on their concentration within the living cells. Some elements, at low concentration, may be beneficial for plant growth and development; however, when present at high concentration, they often exert negative effects. In this regard, understanding the molecular mechanisms involved in the uptake of metalloids by roots, their subsequent transport to different tissues and inter/intra-cellular redistribution has great importance. The mechanisms of metalloids' uptake have been well studied in plants. Also, various transporters, as well as membrane channels involved in these processes, have been identified. In this review, we have discussed in detail the aspects concerning the positive/negative effects of different metalloids on plants. We have also provided a thorough account of the uptake, transport, and accumulation, along with the molecular mechanisms underlying the response of plants to these metalloids. Additionally, we have brought up the previous theories and debates about the role and effects of metalloids in plants with insightful discussions based on the current knowledge.     

Single muscle fiber proteomics reveals unexpected mitochondrial specialization

Mammalian skeletal muscles are composed of multinucleated cells termed slow or fast fibers according to their contractile and metabolic properties. Here, we developed a high‐sensitivity workflow to characterize the proteome of single fibers. Analysis of segments of the same fiber by traditional and unbiased proteomics methods yielded the same subtype assignment. We discovered novel subtype‐specific features, most prominently mitochondrial specialization of fiber types in substrate utilization. The fiber type‐resolved proteomes can be applied to a variety of physiological and pathological conditions and illustrate the utility of single cell type analysis for dissecting proteomic heterogeneity.