Endogenous inhibitors and seasonal changes in abscisic acid in Dioscorea floribunda Mart. & Gal.

In the tubers of medicinal yam (Dioscorea floribunda Mart. & Gal.) abscisic acid (ABA) content was high in all the parts during the dormant condition in the winter, but it decreased to a very low level in the actively growing plants. ABA content of the entire tuber was negatively correlated with temperature and photoperiod. Growth inhibitors including batatasin-I and phthalic acid were identified in the dormant tuber.CIMAP Communication No. 673.     

AFLP fingerprinting and genotypic characterization of some serovars of Bacillus thuringiensis

Amplified fragment length polymorphism (AFLP)-based fingerprinting of 24 serovars of Bacillus thuringiensis (Bt) representing different serotypes was performed using 13 EcoR1 (+2) and Mse1 (+3) primer combinations for genotypic characterization. A high degree of polymorphism was established among the Bt serovars. A total of 1107 fragments ranging from 30–850 bp were generated out of which 1106 were polymorphic. Discrimination rates of different primer combinations at various band levels (1–5) among different Bt serovars were more than 90%. Cluster analysis revealed very low similarity values, ranging from 7–50%, among the Bt serovars indicating their remarkable genetic diversity. AFLP analysis establishes the molecular relatedness between the serovars and serotypes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Variation in resting strategies across trophic levels and habitats in mammals

Mammals must carefully balance rest with other behaviors that influence fitness (e.g., foraging, finding a mate) while minimizing predation risk. However, factors influencing resting strategies and the degree to which resting strategies are driven by the activities of predators and/or prey remain largely unknown. Our goal was to examine how mammalian resting strategies varied with trophic level, body mass, and habitat. We reviewed findings from 127 publications and classified the resting strategies of terrestrial and aquatic mammalian species into three categories: social (e.g., resting in groups), temporal (e.g., resting during the day), or spatial (e.g., resting in burrows). Temporal strategies were most common (54% of cases), but the prevalence of strategies varied with body mass and among trophic levels. Specifically, lower trophic levels and smaller species such as rodents and lagomorphs used more spatial and social resting strategies, whereas top predators and larger species used mostly temporal resting strategies. Resting strategies also varied among habitat types (e.g., rainforest vs. grassland), but this was primarily because closely related species shared both habitats and resting strategies. Human presence also affected resting strategies at all trophic levels but most strongly influenced top predators through shifts in rest timing. Human‐induced behavioral changes in rest patterns cascade to modify behaviors across multiple trophic levels. These findings advance our fundamental understanding of natural history and ecology in wild animals and provide a roadmap for future comparative studies.     

CORTICOTROPHIN INCREASES CEREBRAL POLYAMINE CONTENT

Abstract— To determine whether changes in cerebral polyamines might mediate previously reported ACTH-induced changes in brain biochemistry and behavior, the cerebral content of polyamines was examined following ACTH treatment. Male CD-1 mice were injected daily for 3 days with long-acting (zinc phosphate) preparations of ACTH_1–24 (1 μg/g) or ACTH_4–10 (0.33 μg/g) and killed 24 h after the last injection. Putrescine, spermidine and spermine contents were determined by high pressure liquid chromatography. Putrescine content was significantly elevated in all brain regions by ACTH_1–24 (approx 50%), and in the telencephalon by ACTH_4–10 At the dose tested ACTH_4–10 was less effective than ACTH_1–24. Telencephalic spermidine was also elevated (10%)by ACTH_1–24, but spermine content was not altered in any brain region. One injection of the long-acting ACTH_1–24 preparation elevated telencephalic putrescine (49%) 24 h post-injection. ACTH_1–24 (1 μg/g) in saline produced a peak elevation of all three telencephalic polyamines 6 h post-injection, while in the liver only putrescine was significantly elevated and reached a peak at 10h. Neither plasma polyamine nor ornithine concentrations were significantly altered by any of the treatments. Corticosterone, in both single and multiple injection regimens, failed to alter telencephalic polyamine content. Adrenalectomy, however, prevented the ACTH_1–24-induced increase in telencephalic polyamines. It is concluded that ACTH acts directly in the brain to increase cerebral polyamine concentrations. The possibility that adrenal hormones exert permissive effects on this action is discussed.     

Uptake and translocation of zinc absorbed through roots and fruiting organs in peanuts

Peanut plants (Arachis hypogaea L.) are known to absorb Ca, P and S through the fruiting organs, but information on Zn uptake pattern is lacking. Therefore, a green-house experiment was conducted to study the uptake and translocation of Zn when applied in the rooting and fruiting zones of peanut plants. To locate the pathway and distribution of radioactive Zn, autoradiographs of plants were also taken.Zinc uptake data and autoradiographs indicated that a substantial amount of⁶⁵Zn was absorbed through the fruiting organs (auxillary system). Of the total⁶⁵Zn in the whole plant, 55.2 per cent was absorbed through roots and remaining 44.8 per cent through fruiting organs. Zinc was translocated to all the plant parts regardless of its absorption through roots or fruiting organs. The highest zinc concentration was recorded in the kernels, followed by leaves, stem and the shell.Contribution from the Department of Soils, Haryana Agric. Univ., Hissar-India.