Tunability and noise dependence in differentiation dynamics

The dynamic process of differentiation depends on the architecture, quantitative parameters, and noise of underlying genetic circuits. However, it remains unclear how these elements combine to control cellular behavior. We analyzed the probabilistic and transient differentiation of Bacillus subtilis cells into the state of competence. A few key parameters independently tuned the frequency of initiation and the duration of competence episodes and allowed the circuit to access different dynamic regimes, including oscillation. Altering circuit architecture showed that the duration of competence events can be made more precise. We used an experimental method to reduce global cellular noise and showed that noise levels are correlated with frequency of differentiation events. Together, the data reveal a noise-dependent circuit that is remarkably resilient and tunable in terms of its dynamic behavior.     

Insect antifeedant activity of tetranortriterpenoids from the Rutales. A perusal of structural relations

Structure-related insect antifeedant relationship of 56 limonoids (both natural and modified) from the plants belonging to the order Rutales was attempted considering substitution patterns, oxidation states, and hydrophobicity, as well as distant geometry derived through conformational analysis on molecular modeling. Orientation of the furan and hydroxylation at specific carbon sites have been shown to influence the antifeedancy against the fall armyworm, Spodoptera litura.     

Screening of genotypes of menthol mint Mentha arvensis for high yields of herbage and essential oil under late cropping conditions of the sub-tropical Indo-Gangetic plains

Summary

The essential oil yields and expression of related characters were compared for seven cultivar genotypes of menthol mint Mentha arvensis using two methods of planting in the winter rabi – summer season (October to July) in a sub-tropical agroclimatic environment. The crops of all the cultivars were planted in the field by (1) sowing of suckers on 2 January and (2) transplanting germinated pieces of sucker at different times between 17 March to 14 April. Staggering of transplanting time up to 7 April did not affect oil yields and the related plant growth properties of mint crops. The oil yields of the crops planted on 14 April were lower by about 30%. In the early sucker planted crops, the oil yields were about 30% higher than those obtained from the transplanted crops of 17 March to 7 April and about double that obtained from crops transplanted on 14 April. The oil yields from the crops of the superior genotype Kosi were equal to or higher than the corresponding means of all genotypes under both planting methods. The oil yield from the crops of Kosi genotype obtained by sucker sowing method was estimated as 333 kg ha^–1. The corresponding average yield from the crops of this genotype obtained by transplanting of germinated suckers between 17 March and 7 April was about 293 kg ha^–1 and that from the crop transplanted on 14 April was 218 kg ha^–1. With the Kosi genotype, the latter two types of transplanted mint crops gave oil yields lower only by about 12% and 33% compared with the long-duration sucker-sown crop. It is concluded that a crop of mustard (brassica), Bengalgram (chickpea) or wheat sown between October and November and harvested between early March to middle of April could be taken before cropping of the Kosi genotype of M. arvensis by plantlet transplanting. These results demonstrate the potential of the following rotation of crops in the sub-tropical environments: from June/July/August to October/November (kharif cropping season), rice, maize, sorghum or pigeonpea; from November/December to February/March, mustard and Bengalgram or from November/December to April (rabi cropping season), wheat; from March/April to June/July (zaid cropping season), transplanted menthol mint.     

Phytotransformation of Phorate by <Emphasis Type="BoldItalic">Brassica juncea</Emphasis> (Indian Mustard)

Over 5 days, Brassica juncea removed 54% of the highly toxic insecticide phorate from the medium with the formation of phorate sulfoxide in small quantity. The loss of phorate from the medium followed first-order kinetics. The half-life of phorate disappearance from water decreased by ~4.5-fold in the presence of B. juncea. Mild phorate phytotoxicity was evident from the elevated activities of the antioxidative enzymes like glutathione-disulfide reductase, glutathione S-transferase, superoxide dismutase, and catalase in the plants. Nevertheless, the ubiquitous antioxidative peroxidase was not significantly increased, nor the total glutathione content, due to phorate exposure. Phosphotriester bond hydrolysis and glutathione S-transferase-mediated conjugation seemed to be the key reactions for phorate metabolism by B. juncea. From the limited information available, for the first time, a tentative mapping of phytotransformation pathways was performed.     

Analysis of the coat protein gene of Indian <Emphasis Type="Italic">Potato virus X</Emphasis> isolates for identification of strain groups and determination of the complete genome sequence of two isolates

Complete coat protein (CP) gene sequences of 66 Potato virus X (PVX) isolates were sequenced and compared with other PVX isolates. The CP gene of these isolates shared 93.9–100.0 % and 97.0–100.0 % identities among them at nucleotide and amino acid sequence level, respectively. Phylogenetic analysis with isolates of known PVX strain groups showed that all 66 isolates were found in clade I (strain groups 1, 3 and 4) and none of them in Clade II (strain groups 2 and 4). The Indian isolates had the 714 bp coat protein gene and were closer to clade I isolates with 92.9–99.5 % identities and distantly related to Clade II isolates (74.2 to 80.0 % identities). Hence, these isolates may belong to either of the strain groups 1, 3 and 4. A threonine residue at position 122 and glutamine residue at position 78 were found conserved in all the Indian isolates suggesting that these isolates cannot overcome Rx1gene and Nx gene mediated resistance, characteristic of group 1 and 3. However, unique amino acid substitutions were observed in Indian isolates and further studies are required to ascertain their role in symptom expression, virulence and host range. In addition, whole genome sequences of two isolates one each from Jalandhar (Punjab) and Kufri (Himachal Pradesh) were also determined. They were 6435 nts long with five ORFs and shared 81.4–97.2 % identities to clade I isolates from USA, Russia, India, Iran, China, Japan, Taiwan and 77.0 to 77.5 % identities with clade II isolates from Peru.     

Quantification of Inorganic Anions in Tea (Camellia Sinensis (L) O. Kuntze) Tissues and Soil Using Ion Chromatography Coupled with Conductivity Detector

A simple ion chromatographic method is proposed for the simultaneous quantification of five inorganic anions in samples derived from tea system with a suppressed conductivity detector. For this purpose extracts of leaves, roots and soils of tea obtained at room temperature yielded chromatographic profiles with substantial differences in the relative contents of fluoride (F^?), chloride (Cl^?), nitrate (NO₃^?) and sulfate (SO₄ ^2-). Although Cl^? and SO₄^2- were common to each extracted sample in different categories and accounted for the majority of the anions present, one additional anion peak was detected in root and leaf tissues. Irrespective of the clone and sample investigated the average F^? content varied from 253 to 1664 mg kg^?1, Cl^? varied between 60 and 1789 mg kg^?1, NO₃^? varied from 119 to 188 mg kg^?1 and SO₄^2- varied between 55 and 6779 mg kg^?1. The anionic load was at its crest in clone UPASI – 3 in all the three categories of samples with few exceptions. Among the samples investigated, tea roots contained a considerable amount of major anions, while tea soils had the lowest amount of the detected anions. The recovery of all the quantified anions was above 95%. The correlation coefficient for all anions where above 99.50%. The concentration of nitrite (NO₂^?) was below the limits of detection based on the analytical technique adopted. Anion nitrate was not detected in tea root and tea leaf extracts.     

Current status,opportunities, and challenges of cover cropping for sustainable dryland farming in the Southern Great Plains

Cropping systems that integrate cover crops into crop rotations, reduce tillage intensity and frequency, and maintain residue cover have the potential to improve agricultural sustainability in drylands. However, there is much yet to learn about the benefits of cover crops in sustainable dryland farming in the southern Great Plains (SGP). We reviewed the literature on the effects of cover crops on soil organic carbon (SOC), nitrogen, soil water conservation, and crop yields in dryland cropping systems of the US Great Plains (GP), and analyzed the opportunities and challenges for integrating cover crops into dryland crop-fallow systems of the SGP. Majority of the studies in the central Great Plains (CGP) and the northern Great Plains (NGP) of the United States suggest that cover cropping improves sustainability of cropping systems through their positive effects on SOC accumulation, nutrient cycling, soil erosion control, weed suppression, and soil health improvement. However, integrating cover crops into dryland cropping systems of the SGP faces challenges because of low quantity of soil-water availability. More research on the tradeoff between water use and other agroecosystem benefits of cover cropping is required to successfully integrate cover crops into dryland cropping systems in the SGP.     

Effect of methyl parathion and chlorpyrifos on certain biomarkers in various tissues of guppy fish, Poecilia reticulata

Tests of acute toxicity were performed on the most common species of aquarium fish, Poecilia reticulata. Guppies (P. reticulata) were exposed to progressive concentrations of methyl parathion (MP) and chlorpyrifos (CPF); a semi-static method according to guidelines of OECD was used. Tests of acute toxicity were conducted using 10 fish for each separate concentration and for the control group. The results were subjected to probit analysis to determine the 96 h LC₅₀ values. The 96 h LC₅₀ values of MP and CPF to P. reticulata were 8.48 ppm/L (5.98–10.89) and 0.176 ppm/L (0.313–0.224) respectively. In addition, behavioral changes at each concentration were observed for the individual fish. Fish were exposed for 96 h to different sublethal concentrations of MP and CPF (¼ LC₅₀, 1/8 LC₅₀ and 1/10 LC₅₀) and their oxidative stress-induction potential was estimated in brain, liver and gills of fish. MDA content is induced in all tissues but maximum rise was observed in gills (161% and 153% for MP and CPF respectively). With regard to antioxidant defense system (ADS), GSH level decreased in the brain, liver and gills of tissues of MP treated fishes (22%, 6% and 13% respectively) and showed increase in brain and gills CPF treated (23% and 21% respectively). CAT, GST, GR and SOD levels fluctuated in all treatment groups relative to the control. Brain AChE showed dose-dependent inhibition in fish exposed to the higher concentrations reached 45% and 66% for MP and CPF respectively. Collective findings demonstrated that pesticide exposure of fish induced an increase in MDA and fluctuated ADS along with inhibited AChE. These findings may be used as valuable biomarkers for evaluation of water pollution.     

First record of Asian grey weevil (<Emphasis Type="Italic">Myllocerus undatus)</Emphasis> on coconut from Kerala,India

The occurrence of Asian grey weevil Myllocerus undatus (Curculionidae: Coleoptera) damaging coconut (Cocos nucifera L.) seedlings is reported for the first time from Kerala, India. A mild to moderate level of infestation damaging 5–10% leaf lamina of un-split leaves with a typical notching-like symptom along the leaf margins is noticed on the majority of the coconut seedlings belonging to different coconut varieties, viz., ‘Chowghat Orange Dwarf’, ‘Chowghat Green Dwarf’, ‘Malayan Green Dwarf’, ‘West Coast Tall’ and Dwarf x Tall hybrids. M. undatus has not been reported as a destructive pest on any of the crops from India and is considered to be a pest of quarantine significance. Adult weevils have a characteristic tri-spined hind femur and elytra strongly angled broader than the prothorax.     

Evaluation of the cell-mediated immune response in cattle induced by 2,4-dinitrochlorobenzene

A technique has been evolved and standardized for evaluating the cell-mediated immune (CMI) response in cattle induced by 2,4-dinitrochlorobenzene (DNCB). Six healthy cross-bred Jersey cows were used. The dose and the number of applications for primary sensitization and the challenge dose after the 14th day have been standardized. The gross and histological pictures of the CMI response shown by these cattle are described in detail and their usefulness in assessing the CMI response in various disease conditions including tumour is indicated.