Bimodal oxygen uptake in a freshwater air-breathing fish,Notopterus chitala

Measurements of bimodal oxygen uptake have been made in a freshwater air-breathing fish,Notopterus chitala at 29.0±1(S.D.)°C. xhe mean oxygen uptake from continuously flowing water without any access to air, was found to be 3.58±0.37 (S.E.) ml O₂ · h^?1 and 56.84+4.29 (S.E.) ml O₂ · kg^?1 · h^?1 for a fish weighing 66.92 + 11.27 (S.E.) g body weight. In still water with access to air, the mean oxygen uptake through the gills were recorded to be 2.49 ± 0.31 (S.E.) ml O₂ · h^?1 and 38.78 ± 1.92 (S.E.) ml O₂ · kg^?1 · h^?1 and through the accessory respiratory organs (swim-bladder) 6.04±0.87 (S.E.) ml O₂ · h^?1 and 92.32±2.91 (S.E.) ml O₂ · kg^?1 · h^?1 for a fish averaging 66.92±11.27 (S.E.) g. Out of the total oxygen uptake (131.10 ml O₂ · kg^?1 · h^?1), about 70% was obtained through the aerial route and the remainder 30% through the gills.     

Lactic acid production from whey permeate by immobilized Lactobacillus casei

Two matrices have been assessed for their ability to immobilize Lactobacillus casei cells for lactic acid fermentation in whey permeate medium. Agar at 2% concentration was found to be a better gel than polyacrylamide in its effectiveness to entrap the bacterial cells to carry out batch fermentation up to three repeat runs. Of the various physiological parameters studied, temperature and pH were observed to have no significant influence on the fermentation ability of the immobilized organism. A temperature range of 40–50°C and a pH range of 4.5–6.0 rather than specific values, were found to be optimum when fermentation was carried out under stationary conditions. In batch fermentation ～90% conversion of the substrate (lactose) was achieved in 48 h using immobilized cell gel cubes of 4 × 2 × 2 mm size, containing 400 mg dry bacterial cells per flask and 4.5% w/v (initial) whey lactose content as substrate. However, further increase in substrate levels tested (>4.5% w/v) did not improve the process efficiency. Supplementation of Mg²⁺ (1 mM) and agricultural by-products (mustard oil cake, 6%) in the whey permeate medium further improved the acid production ability of the immobilized cells under study.     

Callus Cultures from Zygotic Embryos of Costus speciosus and Their Morphogenetic Responses

Soft, nodular and hard types of calli were initiated on mature zygotic embryo explants of two tetraploid clones of Costus speciosus, of which, only the hard calli were amenable to morphogenetic responses. The two clones differed in their growth regulator requirements both for the initiation of calli and for shoot regeneration. De novo formation of both shoot bud meristems and somatic embryoids were observed. Latter were encased partially or fUlly by coleoptilar sheath. Embryoids could be isolated as discrete units. On maturity, a stock like appendage developed from the base and finally embryoids got detached from the subtending tissue. Both shoot-bud meristems and somatic embryoids developed into complete plantlets, the former upon sequential transfer of calli on Schenk and Hildebrandt’s (SH) basal medium containing lower levels of growth hormones, while the latter only on basal medium. These culture regenerants were subsequently transferred to the field. The morphogenetic behaviour of these two tetraploid clones reflects their marked genotypic difference inspite of their same ploidy status.     

Genetic and Anatomical Basis of the Barrier Separating Wakefulness and Anesthetic-Induced Unresponsiveness

A robust, bistable switch regulates the fluctuations between wakefulness and natural sleep as well as those between wakefulness and anesthetic-induced unresponsiveness. We previously provided experimental evidence for the existence of a behavioral barrier to transitions between these states of arousal, which we call neural inertia. Here we show that neural inertia is controlled by processes that contribute to sleep homeostasis and requires four genes involved in electrical excitability: Sh, sss, na and unc79. Although loss of function mutations in these genes can increase or decrease sensitivity to anesthesia induction, surprisingly, they all collapse neural inertia. These effects are genetically selective: neural inertia is not perturbed by loss-of-function mutations in all genes required for the sleep/wake cycle. These effects are also anatomically selective: sss acts in different neurons to influence arousal-promoting and arousal-suppressing processes underlying neural inertia. Supporting the idea that anesthesia and sleep share some, but not all, genetic and anatomical arousal-regulating pathways, we demonstrate that increasing homeostatic sleep drive widens the neural inertial barrier. We propose that processes selectively contributing to sleep homeostasis and neural inertia may be impaired in pathophysiological conditions such as coma and persistent vegetative states.     

The importance of leaf surface wax as short-range attractant and oviposition stimulant in a generalist Lepidoptera

Green gram, Vigna radiata (L.) Wilczek, is an important pulse crop of Asia. Severe attack by the larvae of Spilosoma obliqua Walker (Lepidoptera: Arctiidae) causes defoliation of green gram and reduces seed yield. Females lay eggs on the leaf surface, and therefore, surface wax plays an important role as short-range attractant and oviposition stimulant. So, we have attempted to find out whether leaf surface wax compounds (alkanes and free fatty acids) from three green gram cultivars (PDM 54, PUSA BAISAKHI and SAMRAT) could act as short-range attractant and oviposition stimulant in females. The TLC, GC-MS and GC-FID analyses of n-hexane extracts revealed 20 n-alkanes from n-C₁₅ to n-C₃₆ and 13 free fatty acids from C12:0 to C21:0, whilst linoleic acid was unique in SAMRAT. Pentacosane was the predominant amongst n-alkanes in the leaf surface waxes of three cultivars. Heneicosanoic acid and palmitoleic acid were the predominant free fatty acids in the leaf surface waxes of PDM 54, and PUSA BAISAKHI and SAMRAT, respectively. Females were attracted towards one leaf equivalent surface wax of three green gram cultivars against solvent controls (n-hexane) in Y-tube olfactometer bioassays. A synthetic blend of pentacosane, heptacosane, nonacosane, hexatriacontane, palmitoleic acid, linolenic acid and stearic acid, a synthetic blend of pentacosane, hexatriacontane and stearic acid, and a synthetic blend of hexatriacontane, linolenic acid and stearic acid resembling in amounts present in one leaf equivalent surface wax of PDM 54, PUSA BAISAKHI and SAMRAT, respectively, served as short-range attractant and oviposition stimulant in females. Females showed equal preference for egg laying towards the above three synthetic blends when these blends were tested against each other, and hence, these blends could be employed in development of baited traps in pest management strategies.     

Molecular detection and genotyping of Fusarium oxysporum f. sp. psidii isolates from different agro-ecological regions of India

Twenty one isolates of Fusarium oxysporum f. sp. psidii (Fop), causing a vascular wilt in guava (Psidium guajava L.), were collected from different agro-ecological regions of India. The pathogenicity test was performed in guava seedlings, where the Fop isolates were found to be highly pathogenic. All 21 isolates were confirmed as F. oxysporum f. sp. psidii by a newly developed, species-specific primer against the conserved regions of 28S rDNA and the intergenic spacer region. RAPD and PCR-RFLP were used for genotyping the isolates to determine their genetic relationships. Fifteen RAPD primers were tested, of which five primers produced prominent, polymorphic, and reproducible bands. RAPD yielded an average of 6.5 polymorphic bands per primer, with the amplified DNA fragments ranging from 200–2,000 bp in size. A dendrogram constructed from these data indicated a 22–74% level of homology. In RFLP analysis, two major bands (350 and 220 bp) were commonly present in all isolates of F. oxysporum. These findings provide new insight for rapid, specific, and sensitive disease diagnosis. However, genotyping could be useful in strain-level discrimination of isolates from different agro-ecological regions of India.