Carbondioxide gating in silk cocoon

Silk is the generic name given to the fibrous proteins spun by a number of arthropods. During metamorphosis, the larva of the silk producing arthropods excrete silk-fiber from its mouth and spun it around the body to form a protective structure called cocoon. An adult moth emerges out from the cocoon after the dormant phase (pupal phase) varying from 2 weeks to 9 months. It is intriguing how CO(2)/O(2) and ambient temperature are regulated inside the cocoon during the development of the pupa. Here we show that the cocoon membrane is asymmetric, it allows preferential gating of CO(2) from inside to outside and it regulates a physiological temperature inside the cocoon irrespective of the surrounding environment temperature. We demonstrate that under simulating CO(2) rich external environment, the CO(2) does not diffuse inside the cocoon. Whereas, when CO(2) was injected inside the cocoon, it diffuses out in 20 s, indicating gating of CO(2) from inside to outside the membrane. Removal of the calcium oxalate hydrate crystals which are naturally present on the outer surface of the cocoon affected the complete blockade of CO(2) flow from outside to inside suggesting its role to trap most of the CO(2) as hydrogen bonded bicarbonate on the surface. The weaved silk of the cocoon worked as the second barrier to prevent residual CO(2) passage. Furthermore, we show that under two extreme natural temperature regime of 5 and 50 °C, a temperature of 25 and 34 °C respectively were maintained inside the cocoons. Our results demonstrate, how CO(2) gating and thermoregulation helps in maintaining an ambient atmosphere inside the cocoon for the growth of pupa. Such natural architectural control of gas and temperature regulation could be helpful in developing energy saving structures and gas filters.     

Diversity analysis of Tomato leaf curl New Delhi virus-[potato], causing apical leaf curl disease of potato in India

The complete coat protein (cp) gene sequence of eighty Tomato leaf curl New Delhi virus-[potato] (ToLCNDV-[potato]) isolates collected from eleven states were determined. Phylogenetic analysis based on cp gene grouped the isolates into two major clades (I & II) and they shared 95.9–100.0% identity. The DNA A and DNA B of eight representative isolates (six from clade I and two from clade II) were 2739–2740 and 2692–2694 nts long and shared 94.6–99.4% and 97.2–99.5% homology within the isolates, respectively. Among the eight isolates, the DNA A of two isolates (Clade II), GWA-5 and FAI-19 had 94.6–95.3% sequence identity to other six isolates and formed a sub-clade within the ToLCNDV-[potato] isolates. Similar grouping was also revealed with AC1 and AC4 genes of these eight isolates. The DNA A components shared more than 90.0% identity with the DNA A of ToLCNDV isolates from cucurbitaceous crops, tomato, bhendi, 89.0–90.0% with ToLCNDV-papaya isolates and 70.4–74.0% with other tomato leaf curl viruses. Hence, the begomovirus infecting potatoes are the ToLCNDV isolates, designated as ToLCNDV-[potato]. Whereas, the DNA B components shared 86.6–91.7% identity with ToLCNDV isolates from cucurbits, tomato and bhendi. Evidence for intra-species recombination was detected only in DNA A with a maximum of three events in GWA-5 and FAI-19 isolates. Analysis of cp gene, DNA A, iterons and recombination events clearly indicate that two groups of ToLCNDV-[potato] infects potato in India.     

Immunogenicity and protective effects of truncated recombinant leukotoxin proteins of Fusobacterium necrophorum in mice

Fusobacterium necrophorum, a gram-negative, anaerobic and rod-shaped bacterium, is generally an opportunistic pathogen and causes a wide variety of necrotic infections in animals and humans. Leukotoxin, a secreted protein, is a major virulence factor. The gene encoding the leukotoxin (lktA) in F. necrophorum has been cloned, sequenced and expressed in Escherichia coli. Because of low expression levels, problems associated with purifying full-length recombinant protein, and of the physical instability of the protein, five overlapping leukotoxin gene truncations were constructed. The recombinant polypeptides (BSBSE, SX, GAS, SH, and FINAL) were expressed in E. coli and purified by nickel-affinity chromatography. The objectives were to investigate the effectiveness of the purified truncated polypeptides to induce protective immunity in mice challenged with F. necrophorum. The polypeptides, individually or in combination, and inactivated native leukotoxin or culture supernatant of F. necrophorum were homogenized with an adjuvant and injected into mice on days 0 and 21. Blood samples were collected to measure serum anti-leukotoxin antibody titers on days 0, 21 and 42 and on day 42, mice were experimentally challenged with F. necrophorum. All polypeptides were immunogenic, with GAS polypeptide eliciting the least antibody response. Two polypeptides (BSBSE and SH) induced significant protection in mice against F. necrophorum infection. Protection was better than the full-length native leukotoxin or inactivated supernatant.The study demonstrated that the leukotoxin of F. necrophorum carries epitopes that induce protective immunity against experimental fusobacterial infection, thus providing further evidence to the importance of leukotoxin as a major virulence factor.     

Dietary supplementation of dried plum: a novel strategy to mitigate heat stress in broiler chickens

Background: Heat stress is a significant problem in the poultry industry, causing a severe economic loss due to its detrimental effects on chickens' health and performance. Dried plum(DP) is a good source of minerals, vitamins,antioxidants, and phenolic compounds. Studies have suggested that DP has several health benefits, such as maintaining the body's redox system, immune status, and calcium hemostasis. Based on the health benefits of DP,we hypothesized that the dietary supplementation of DP would alleviate the detrimental effects of heat stress on broiler chickens.Results: To test the hypothesis, day-old broiler chicks(n = 72) were randomly allocated to three treatment groups(n = 24/group): no heat stress(NHS), heat stress(HS), and heat stress with dried plum(HS + DP), and reared under standard conditions. The inclusion of 2.5% DP in the feed of the HS + DP group was made during the treatment period, while birds in other groups were provided with a standard finisher diet. After 21 days, birds in the HS and HS + DP groups were exposed to cyclic heat stress conditions(33 °C for 8 h during daytime) for 3 weeks, while those in the NHS group were reared under normal conditions(22–24 °C). Weekly body weight and feed intake were recorded to calculate the average daily gain(ADG), average daily feed intake(ADFI), and feed conversion ratio(FCR). Heat stress significantly decreased the final body weight, ADG, ADFI, and increased FCR compared to the NHS group, whereas dietary supplementation of DP significantly improved these growth performance parameters compared to the HS group. Furthermore, supplementation of DP significantly increased the expression of heat shock protein-related genes(HSF1, HSF3, HSP70, and HSP90), antioxidant-related genes(SOD1, SOD2, GPX1, GPX3,PRDX1, and TXN), tight junction-related genes(CLDN1, and OCLN), and immune-related genes(IL4, MUC2) in the ileum as compared to the HS group. The microbiota analysis showed significant enrichment of Bacillales,Christensenellaceae, Bacillaceae, Peptostreptococcaceae, and Anaerotruncus in heat-stressed birds supplemented with DP as compared to the HS group. Further, DP supplementation also significantly increased the concentration of acetate, propionate, and total VFA in the cecal digesta of the HS + DP group as compared to the HS group.Conclusion: These findings suggest that DP supplementation effectively improved the growth performances and gut health parameters in the heat-stressed birds. Thus, dried plum can be a potential feed supplement to mitigate heat stress in broiler chickens.     

Effects of vertebrate herbivores and shrub characteristics on arthropod assemblages in a northern Arizona forest ecosystem

Large herbivores have potential to affect invertebrate community structure through numerous processes, but little work has been done to evaluate the relative importance of direct and indirect factors. In this study, we measured arthropod community assemblages on Ceanothus fendleri A. Gray (Fendler's ceanothus) plants that were growing inside and outside of 4-m² exclosures. We used univariate analyses and structural equation modeling (SEM) to evaluate relationships within this herbivore–plant–arthropod system in ponderosa pine (Pinus ponderosa Laws.) forests of northern Arizona, USA. Results showed that individual arthropod abundance, family diversity, family richness, and functional group richness were significantly greater on plots where C. fendleri plants were protected from large ungulate herbivores (e.g., mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus nelsoni)) than on unprotected plots in each of the three study years. Results also indicated the following: (1) arthropod abundance was significantly greater on protected plants than unprotected plants; (2) rarefaction curves suggested arthropod family richness was similar between protected and unprotected plants in two of the three years when scaled by number of individuals but the estimated total richness was consistently higher on protected plants; (3) arthropod abundance was directly affected by protection from herbivores, plant stem length, and number of flowers; (4) arthropod family richness was related to the number of individuals collected and affected by stem length. Results from this study illustrate that arthropod communities are directly affected by foraging vertebrate herbivores as well as indirectly affected through complex plant-mediated factors in this model system. Protection of preferred forage plants such as C. fendleri from ungulate herbivores can potentially increase diversity of arthropod assemblages in these forests, help conserve biological diversity, and enhance ecosystem restoration efforts.     

Role of compost biochar amendment on the (im)mobilization of cadmium and zinc for Chinese cabbage (Brassica rapa L.) from contaminated soil

Journal of Soils and Sediments - This study aims to assess the effect of amendment of an alkaline Zn, Cd-contaminated soil with compost of wheat straw biochar (CB) (4, 8, 12, and 18%) and sludge...     

Improvement in growth and alkaloid content of Rauwolfia serpentina on application of organic matrix entrapped biofertilizers (Azotobacter chroococcum,Azospirillum brasilense and Pseudomonas putida)

The field experiment was conducted to study the effect of conventional chemical fertilizer (urea),conventional biofertilizers (charcoal based) and organic matrix entrapped biofertilizer; (OMEB: a consortium of Azotobacter chroococcum, Azospirillum brasilense and Pseudomnas putida entrapped with clay soil, neem leaves, and cow dung in ratio of 1:1:1 and 15% saresh (plant gum of Acacia sp.) in various doses on growth parameters of Rauwolfia serpentina in terms of root length, shoot length, number of leaves, number of roots and fresh and dry weight of roots and shoots. Replacement of conventional chemical fertilizer by the consortium of biofertilizers (un-entrapped) increased plant growth in a dose dependent manner up to triple dose of the recommended dose (RD) of biofertilizers (1.80 kg ha-1). This increase in plant growth was not up to the level which appeared in the application of RD of urea. Entrapment of the same biofertilizers in an organic matrix mentioned above enhanced the plant growth similar to that observed for urea. The percentage increase of 9.57 and 7.54 in fresh weight (FW) and 11.93 and 11.12% in dry weight (DW) of shoot and 17.94 and 37.87% in FW of roots and 31.90 and 50.08% in DW of roots were recorded in 75 days old plant by the application of OMEB- triple dose over the conventional biofertilizers triple dose and recommended dose of urea. Conventional biofertilizers enhanced the availability of nitrate, nitrite and phosphate in the roots and leaves of the plant over application of urea as well as conventional biofertilizers. This formulation also increased alkaloid contents of in the roots of this plant. Microbial population of soil was also improved indicating enhanced soil fertility with application of OMEB. The results indicate that replacement of chemical fertilizers with microbial biofertilizers is possible with application of higher dose of biofertilizers entrapped into the organic matrix for the cultivation of medicinal plants like R. serpentina.