Stable isotope analyses of belemnites from the Kachchh Basin,western India: paleoclimatic implications for the Middle to Late Jurassic transition

Stable isotope analyses of 61 diagenetically unaltered belemnite rostra from the Middle to Late Jurassic of the Kachchh Basin of western India suggest stable paleotemperatures across the Callovian-Oxfordian boundary (~14°C). Only at the end of the Middle Oxfordian water temperatures drop for more than 3°C before reaching again higher values during the Kimmeridgian (~12.3°C). The data do not support polar glaciations proposed for the Middle to Late Jurassic transition, which necessarily would have led to a global temperature and sea-level minimum at the boundary. Callovian to Oxfordian rocks in the Kachchh Basin point to a gradual shallowing corresponding to a slight fall in relative sea level. However, the magnitude of this regression is comparatively small, and the sea-level minimum is reached in the late Early Oxfordian and not close to the boundary. Results from the Kachchh Basin therefore, imply almost stable climatic conditions during the Middle to Late Jurassic transition and do not show any evidence for polar glaciations.     

Effect of Gymnema montanum Leaves on Serum and Tissue Lipids in Alloxan Diabetic Rats

The effect of Gymnema montanum leaves on alloxaninduced hyperlipidemia was studied in male Wistar rats. Ethanolic extract of G. montanum leaves was administered orally and different doses of the extract on blood glucose, serum and tissue lipids, hexokinase, glucose-6-phosphatase, thiobarbituric acid–reactive substances (TBARS), hydroperoxides, and glutathione in alloxan-induced diabetic rats were studied. G. montanum leaf extract (GLEt) at doses of 50, 100, 200 mg/kg body weight for 3 weeks suppressed the elevated blood glucose and lipid levels in diabetic rats. GLEt at 200 mg/kg body weight was found to be comparable to glibenclamide, a reference drug. These data indicate that G. montanum represents an effective antihyperglycemic and antihyperlipidemic adjunct for the treatment of diabetes and a potential source of discovery of new orally active agent for future therapy.     

Allele mining for a drought responsive gene DRO1 determining root growth angle in donors of drought tolerance in rice (Oryza sativa L.)

Deeper Rooting 1 (DRO1) gene identified from a major QTL on chromosome 9 increases the root growth angle (RGA) and thus facilitates survival under drought and hence is an excellent candidate for rice improvement. Twenty-four major Indian upland and lowland genotypes including the ‘yield under drought’ (DTY) QTL donors were subjected to allele mining of DRO1 (3058 bp) using four pairs of overlapping primers. A total of 216 and 52 SNPs were identified across all genotypes in the gene and coding region (756 bp) respectively with transversions 3.6 fold more common than transitions in the gene and 2.5 times in the CDS. In 251 amino acid long protein, substitutions were found in 19 positions, wherein change in position 92 was the most frequent. Based on allele mining, the 24 genotypes can be classified into 16 primary structure variants ranging from complete functional allele (Satti, IR36 and DTY 3.1 donor, IR81896-B-B-195) to truncated non-functional alleles in PMK2, IR64, IR20 and Swarna. All the DTY donors, other than IR81896-B-B-195, and most of the upland drought tolerant cultivars (Nagina 22, Vandana and Dhagaddeshi) had accumulated 6–19 SNPs and 4–8 amino acid substitutions resulting in substantial differences in their protein structure. The expression analysis revealed that all the genotypes showed upregulation under drought stress though the degree of upregulation varied among genotypes. The information on structural variations in DRO1 gene will be very useful for the breeders, especially in the light of recent breeding programmes on improving drought tolerance using several DTY donors and upland accessions.Supplementary InformationThe online version of this article (10.1007/s12298-021-00950-2).     

Characterization of a small endogenous plasmid from the CyanobacteriumPlectonema boryanum

The nonheterocystous filamentous CyanobacteriumPlectonema boryanum strain UTEX 594 contains at least two plasmids. A small 145 kb plasmid was cloned in pBR322. It has no homology with the bigger resident plasmid or with chromosomal DNA. A small fraction of the plasmid is present in the form of multimers or concatemers. Copy number and hybridization patterns of the plasmid were similar under dinitrogen-fixing and non-fixing conditions. Restriction site mapping of the plasmid was done to enable its use in the development of cyanobacterial cloning vectors. It is among the smallest natural plasmids reported from bacteria.     

Effect of distal sugars and interglycosidic linkage on the N-glycoprotein linkage region conformation: synthesis and X-Ray crystallographic investigation of β-1-N-alkanamide derivatives of cellobiose and maltose as disaccharide analogs of the conserved chitobiosylasparagine linkage

The linkage region constituents, 2-deoxy-2-acetamido-β-D-glucopyranose (GlcNAc) and L-asparagine (Asn) are conserved in the N-glycoproteins of all eukaryotes. Elucidation of the structure and conformation of the linkage region of glycoproteins is important to understand the presentation and dynamics of the carbohydrate chain at the protein/cell surface. Earlier crystallographic studies using monosaccharide models and analogs of N-glycoprotein linkage region have shown that the N-glycosidic torsion, ?_N, is more influenced by the structural variation in the sugar part than that of the aglycon moiety. To access the influence of distal sugar as well as interglycosidic linkage (α or β) on the N-glycosidic torsion angles, cellobiosyl and maltosyl alkanamides have been synthesized and structural features of seven of these analogs have been characterized by X-ray crystallography. Comparative analysis of the seven disaccharide analogs with the reported monosaccharide analogs showed that the ?_N value of cellobiosyl analogs deviate ~9° with respect to GlcβNHAc. In the case of maltosyl analogs, deviation is more than 18°. These deviations indicate that the N-glycosidic torsion is influenced by addition of distal sugar as well as with respect to inter glycosidic linkage (α or β); it is less influenced by changes occurring at the aglycon. The χ₂ value of alkanamide derived from glucose, cellobiose and maltose exhibit a large range of variations (from 1.6° to ?109.9°). This large span of χ₂ value suggests the greater degree of rotational freedom around C1′-C2′ bond which is restricted in GlcNAc alkanamides. The present finding explicitly proved the importance of molecular architecture in the N-glycoproteins linkage region to maintain the linearity, planarity and rigidity. These factors are necessary for N-glycan to serve role in inter- as well as intramolecular carbohydrate-protein interactions.     

Evaluation of insecticidal properties of botanicals for sustainable management of sucking pests of horticultural crops

Aphids, thrips, whiteflies, mealy bugs and mites could cause significant yield losses in horticultural crops. Many synthetic chemicals highly hazardous to non-target organisms and the environment are in use in their management. Botanicals are ideal for safe sustainable pest management by keeping synthetic chemical use at a minimum. We studied the insecticidal properties of three botanicals viz., Annona squamosa, Ricinus communis and Sapindus mukorossi seed extracts against sucking pests viz., aphids (Aphis gossypii and Aphis craccivora) on okra (Abelmoschus esculentus) and bittergourd (Momordica charantia), thrips (Scirtothrips dorsalis) on chilli (Capsicum frutescens), whiteflies (Bemisia tabaci) on eggplant (Solanum melongena), mealy bugs (Maconellicoccus hirsutus) on betel vine (Piper betle) and mites (Tetranychus urticae) on eggplant (Solanum melongena) under laboratory conditions. The bioassay showed that A. squamosa seed extract has potent insecticidal properties on all sucking pests, except T. urticae. Though S. mukorossi seed extract exhibited no insecticidal property, had a significant acaricidal property. A. squamosa and S. mukorossi seed extracts will therefore be additional botanicals for use in organic farming for managing the sucking pests effectively.