Bedout: a possible end-Permian impact crater offshore of northwestern Australia

The Bedout High, located on the northwestern continental margin of Australia, has emerged as a prime candidate for an end-Permian impact structure. Seismic imaging, gravity data, and the identification of melt rocks and impact breccias from drill cores located on top of Bedout are consistent with the presence of a buried impact crater. The impact breccias contain nearly pure silica glass (SiO2), fractured and shock-melted plagioclases, and spherulitic glass. The distribution of glass and shocked minerals over hundreds of meters of core material implies that a melt sheet is present. Available gravity and seismic data suggest that the Bedout High represents the central uplift of a crater similar in size to Chicxulub. A plagioclase separate from the Lagrange-1 exploration well has an Ar/Ar age of 250.1 +/- 4.5 million years. The location, size, and age of the Bedout crater can account for reported occurrences of impact debris in Permian-Triassic boundary sediments worldwide.     

Origin of the sudbury complex by meteoritic impact: neodymium isotopic evidence

Samarium-neodymium isotopic data on whole rocks and minerals of the Sudbury Complex in Canada gave an igneous crystallization age of 1840 +/- 21 x 10(6) years. The initial epsilon neodymium values for 15 whole rocks are similar to those for average upper continental crust, falling on the crustal trend of neodymium isotopic evolution as defined by shales. The rare earth element concentration patterns of Sudbury rocks are also similar to upper crustal averages. These data suggest that the Sudbury Complex formed from melts generated in the upper crust and are consistent with a meteoritic impact.     

The Seismic Structure of the Sun

Global Oscillation Network Group data reveal that the internal structure of the sun can be well represented by a calibrated standard model. However, immediately beneath the convection zone and at the edge of the energy-generating core, the sound-speed variation is somewhat smoother in the sun than it is in the model. This could be a consequence of chemical inhomogeneity that is too severe in the model, perhaps owing to inaccurate modeling of gravitational settling or to neglected macroscopic motion that may be present in the sun. Accurate knowledge of the sun's structure enables inferences to be made about the physics that controls the sun; for example, through the opacity, the equation of state, or wave motion. Those inferences can then be used elsewhere in astrophysics.     

Effect of nitrogen nutrition of stock plants of Justicia gendarussa L. on the rooting of cuttings

The effect of the nitrogen nutrition of stock plants of Justicia gendarussa L. on the rooting of cuttings was studied in sand culture under high, medium and low levels of nitrogen.

Nitrogen starvation induced rooting. Exogenous application of the auxins IAA (indol-3yl-acetic acid), IBA (indol-3yl-butyric acid) and NAA (naphth-lyl-acetic acid) greatly increased the rooting response of cuttings from-stock plants grown with small amounts of nitrogen.

The root-promoting effect of a low nitrogen supply was associated with a retardation of growth in the stock plants from which the cuttings were made. High C/N (total available carbohydrates/total nitrogen) and P/N (total phosphorus/total nitrogen) ratios increased anthocyanin pigmentation in the shoot, and increased rooting cofactor activity in the tissues of cuttings. The phenolic compounds, ferulic acid, p-hydroxybenzoic acid and p-coumaric acid were present in the shoots of all three nutritional treatments and acted as important cofactors in the cuttings. In general, rooting cofactor activity was inversely related to nitrogen supply and the activity was highest under low nitrogen.

The cuttings taken from plants grown under different levels of nitrogen interacted differentially with the exogenously applied auxins.     

Molecular characterization,inductive expression and mechanism of interleukin‐10 gene induction in the Indian major carp,catla (Catla catla)

Interleukin‐10 (IL‐10) is a multifunctional cytokine and plays an important role in diseases. In this study, IL‐10 gene was cloned and characterized from catla (Catla catla), which is a highly commercially important fish species in the Indian subcontinent. The result indicated that the full‐length catla IL‐10 (cIL‐10) gene had five exons and four introns with an open reading frame of 540 nucleotides encoding a polypeptide of 179 amino acids. A phylogenetic analysis of cIL‐10 gene sequence showed that cIL‐10 clustered with freshwater carps group as expected. Quantitative real‐time polymerase chain reaction analysis showed that cIL‐10 was expressed in gill, liver, kidney, intestine, skin and heart and its expression profile was up‐regulated in bacterial infection and LPS treatment. A close relationship of high cIL‐10 expression and low pro‐inflammatory cytokine IL‐1β expression was observed in the treated group of fish, which might reveal the role of cIL‐10 as an anti‐inflammatory cytokine. Mechanism of cIL‐10 induction was investigated by blocking nuclear factor (NF)‐κB ‐signalling with BAY 11‐7082 in catla kidney cell culture. Blocking NF‐κB suppressed IL‐10 induction by LPS, and thus it revealed that cIL‐10 was induced through NF‐κB signalling. These data could be helpful to understand the function of IL‐10 in fish in response to vaccinations, probiotics and various diseases.     

Direct shoot organogenesis from rhizomes of medicinal zingiber <Emphasis Type="Italic">Alpinia calcarata</Emphasis> Rosc. and evaluation of genetic stability by RAPD and ISSR markers

A simple and efficient protocol for direct in vitro shoot multiplication and plant regeneration was established for an important aromatic medicinal plant, Alpinia calcarata. Preinduction of rhizome segments in medium containing 8.8 μM 6-benzylamino purine (BAP) rescued the buds from dormancy in 60% of the cultures. An average of 6.2 shoots were produced from rhizomatous bud explants on Murashige and Skoog (MS) medium supplemented with 5 μM BAP, 10 μM kinetin, and 2.5 μM α-Naphthalene acetic acid (NAA). The mother cultures retained their morphogenetic potential upto four subcultures and a maximum of 1.77-fold increase in shoot multiplication was recorded after the 3^rd subculture. Rooting was simultaneously induced during subculture on shoot multiplication medium eliminating an additional step for rooting induction. Rooted plantlets were successfully acclimatized in pots in the greenhouse and subsequently established in the experimental garden without any visible symptoms of wilting and necrosis. The genetic fidelity of regenerated plants was evaluated by adapting to two PCR-based DNA marker techniques, Random Amplified Polymorphic DNA (RAPD) and Inter Simple Sequence Repeats (ISSR) which detected no variability in the in vitro multiplied plantlets of A. calcarata. This efficient method of clonal multiplication may be useful for commercial scale multiplication, and in situ and ex situ conservation of elite germplasm of A. calcarata.     

Evaluation of wild Arachis species for abiotic stress tolerance: I. Thermal stress and leaf water relations

The Indian groundnut cultivars have a narrow genetic base. Hence, it was of interest to investigate the genetic variability among wild Arachis species and their accessions for tolerance to thermal stress. A wide variation was observed in leaf morphological characters such as colour, shape, hairiness, length and width and thickness (SLA). The temperature and time required for 50% leaf injury was worked out with limited number of genotypes and was found to be 54°C for 50 min. Among 36 genotypes (having SLA in the range of 66 and 161 cm² g⁻¹) screened, the inherent potential for cold as well as heat tolerance in terms of relative leaf injury (RI) was observed. Thus, based on RI-values, A. glabrata 11824 and A. paraguariensis 12042 were identified as heat-tolerant and cold-tolerant genotypes, respectively while A. appresipila 11786 was found to be susceptible to both heat and cold. Correlation between SLA and RI values for heat (r = 0.38, P < 0.05) and cold (r = 0.52, P < 0.05) tolerance was positive, indicating that thicker the leaf the lower the injury or higher the tolerance. Among six species and 13 accessions, comprising both heat-tolerant and heat- susceptible genotypes, the concentrations of various leaf chemical constituents such as total protein, phenols, sugars, reducing sugar, amino acids, proline, epicuticular wax load and chlorophyll varied significantly. The epicuticular wax load ranged between 1.1 and 2.5 mg dm² among 13 A.glabrata accessions. These accessions were categorized into two groups, i.e. high-wax (range: 2.0–2.5 mg dm²) and low-wax types (range: 1.1–1.6 mg dm²). The high-wax type showed a higher diffusion resistance (dr) as compared to low-wax type; though the transpiration rate (tr) in high-wax type was moderate (between 9.5 and 11.6 μg cm⁻² s⁻¹). Genetic variability in parameters such as canopy temperature, dr and tr was also distinct. The fully turgid leaves with relative water content ≥91%, showed leaf water potential (ψ_leaf) between −0.7 and −1.2 MPa. Results indicated that the plants with thicker leaves are better protected from heat injuries. Further, epicuticular wax load seems to help in maintaining stomatal regulation and leaf water relations, thus affording adaptation to wild Arachis species to thrive under water-limited environments. The sources of tolerance, as identified in this study, could be utilized to improve thermal tolerance of the groundnut cultivars by intra-specific hybridization, following either conventional breeding using embryo rescue techniques, if required or utilizing biotechnological tools.     

<Emphasis Type="Italic">Fusarium</Emphasis> elicitor-dependent calcium influx and associated ros generation in tomato is independent of cell death

Fusarium oxysporum f. sp. lycopersici elicitor (EFOL-2) treatment induces cytosolic influx of calcium in Fusarium-resistant tomato suspension culture. The calcium signature was found to be biphasic, which is characteristic of recognition of oligosaccharides in the elicitor preparation. Further, several lines of evidence such as, (i) attainment of saturation level of the [Ca²⁺]_cyt at a definite extra-cellular calcium concentration (ii) prominent reduction in EFOL-2-induced influx in [Ca²⁺]_cyt on treatment with the calcium channel blockers verapamil and diltiazem and (iii) establishment of a refractory stage of [Ca²⁺]_cyt level upon repeated stimulation by EFOL-2, is indicative of receptor-mediated activation of the calcium channel for cytosolic elevation. In addition, inhibition of EFOL-2-induced [Ca²⁺]_cyt increase by protein kinase inhibitor staurosporine and wortmannin indicate phosphorylation is a regulatory event of calcium influx. Additionally, monitoring of cell death on EFOL-2 treatment indicated that the degree of ROS generation is not capable of inducing cell death. Inhibition of ROS generation on two separate occasions such as, calcium-free media and on treatment with inhibitors causing calcium channel occlusion revealed ROS generation as a successive event of calcium influx.     

Autoregressive technique in length growth modelling of two Indian major carp, Catla catla (Hamilton) and Labeo rohita (Hamilton), reared under two holding conditions

An autoregressive analysis was performed on data from an investigation of the velocity and acceleration of the day-to-day length increments of two Indian major carp, Catla catla (Hamilton) and Labeo rohita (Hamilton), hatched in artificial (Chinese-style hatchery) and semi-natural (improvised pits) holding conditions. The autoregressive model, which was capable of providing short- and long-term predictions, was tested in parallel with a time regressive model and an instantaneous growth rate model. The estimate simulating short-term predictions was found to describe the data more efficiently than the other estimates of the models. Product-moment correlations comparing the two holding systems revealed no source-specific variation of growth between the species. However, the significant length velocity correlation suggests that the artificial system has greater efficacy.