Secretion of Acid Phosphatase by x4xenic Entamoeba histolytica NIH-200 and Properties of the Extracellular Enzyme

Entamoeba histolytica (NIH-200) secreted large amounts of acid phosphatase in its external environment when grown axenically in modified TPS-II medium. Fractionation by DEAE-cellulose chromatography of the precipitate obtained from the cell-free medium at 60% ammonium sulfate saturation yielded 3 distinct peaks of enzyme activity. The enzyme in all the peaks showed resistance to tartrate but was inhibited by fluoride, cupnc chloride, ethylene diamine-tetra acetic acid, ammonium molybdale and cysteine: however, enzyme associated with different peaks differed in its polyacrylamide gel electrophoretic profiles and behavior towards concanavalin A.     

Microclimatic factors associated with elevational changes in army ant density in tropical montane forest

Abstract.  1. The density (rate of encountering foraging raids) and species richness of army ants (Formicidae: Ecitoninae, and behaviourally convergent Ponerinae) was measured in montane tropical forest. Above-ground and subterranean army ant raids were sampled using standard protocols at four sites across an elevational gradient (1200–1650 m above mean sea level) in and near cloud forest in the area of Monteverde, Costa Rica.
2. Mean ambient temperature differed among sites, and decreased with elevation. For the above-ground foraging army ant species, raid rates also declined with elevation. Surface army ant raid rates, however, were not affected by day to day weather variation within sites (temperature, cloud cover, or precipitation).
3. For the underground foraging army ant species, raid rates did not vary directionally with elevation, and subterranean raid rates were not affected by day to day weather variation within sites.
4. Army ant species richness was not directionally related to elevation, and species sharing among sites was generally high.
5. Army ant community structure changes with elevation in Neotropical montane forest, and the results suggest that the strongest effects are of temperature regimes on the density of raids. These findings provide a baseline against which to detect changes in army ant communities that may accompany directional climate change in tropical cloud forests.     

Canavanine-lnduced inhibition of growth and heterocyst differentiation inAnabaena doliolum and isolation of a canavanine-resistant mutant

The effect of the arginine analogue, canavanine on growth and heterocyst differentiation in the nitrogen-fixing algaAnabaena doliolum has been studied. The analogue inhibited growth and heterocyst differentiation at a concentration as low as 1 μM. The treated algal cells lacked conspicuous granular inclusions, whereas treatment with chloramphenicol led to increased synthesis of granules (probably cyanophycin granules). Exogenously added arginine completely reversed the effect of the analogue but lysine could only partially relieve the effect. A time course study with canavanine indicated inhibition of fresh protein(s) synthesis at all steps where a new class of proteins is synthesized so that the action of the analogue does not seem to be specific for a particular kind of protein. A mutant resistant to this analogue has been successfully isolated indicating that this alga does not show mutational immunity at least to the amino acid analogues unlike in the observation with different antibiotics. Our observations indicate that canavanine either directly inhibits protein synthesis or forms defective protein(s) which produces all the observed effects.     

Morphological and Biochemical Investigations on Ipomoea Seedlings and their Species Interrelationships

Studies on seedling morphology and the isozyme profile of 12species ofIpomoea , undertaken with a view to tracing the linkageand homology between the species, revealed the concordance ofmorphological findings with biochemical analysis. The trendof clustering in the dendrogram based on isozyme profiles revealedtwo broad clusters or groups. Interrelationships and homologybetween the species revealed by the phyletic tree constructedfrom seedling morphology and from the dendrogram on isozymedata were comparable, with only minor variations. Ipomoea spp.; seedlings; morphology; isozymes; dendrogram; phyletic tree     

Roles,and establishment,maintenance and erasing of the epigenetic cytosine methylation marks in plants

Heritable information in plants consists of genomic information in DNA sequence and epigenetic information superimposed on DNA sequence. The latter is in the form of cytosine methylation at CG, CHG and CHH elements (where H = A, T or C) and a variety of histone modifications in nucleosomes. The epialleles arising from cytosine methylation marks on the nuclear genomic loci have better heritability than the epiallelic variation due to chromatin marks. Phenotypic variation is increased manifold by epiallele comprised methylomes. Plants (angiosperms) have highly conserved genetic mechanisms to establish, maintain or erase cytosine methylation from epialleles. The methylation marks in plants fluctuate according to the cell/tissue/organ in the vegetative and reproductive phases of plant life cycle. They also change according to environment. Epialleles arise by gain or loss of cytosine methylation marks on genes. The changes occur due to the imperfection of the processes that establish and maintain the marks and on account of spontaneous and stress imposed removal of marks. Cytosine methylation pattern acquired in response to abiotic or biotic stress is often inherited over one to several subsequent generations. Cytosine methylation marks affect physiological functions of plants via their effect(s) on gene expression levels. They also repress transposable elements that are abundantly present in plant genomes. The density of their distribution along chromosome lengths affects meiotic recombination rate, while their removal increases mutation rate. Transposon activation due to loss of methylation causes rearrangements such that new gene regulatory networks arise and genes for microRNAs may originate. Cytosine methylation dynamics contribute to evolutionary changes. This review presents and discusses the available evidence on origin, removal and roles of cytosine methylation and on related processes, such as RNA directed DNA methylation, imprinting, paramutation and transgenerational memory in plants.     

Characterization of MTNR1A gene in terms of genetic variability in a panel of subtemperate and subtropical Indian sheep breeds

Seasonality of animals is an important adaptive trait for successful survival and production during limited food availability and extreme environmental conditions. Photoperiodic changes in day length are utilized by these seasonal animals as an important environmental cue for regulating their annual rhythms of reproduction cycles. Melatonin is an important hormone which is secreted by the pineal gland in proportion to darkness and its effect is mediated by melatonin receptor subtypes, principally MTNR1A. In the present study, polymorphism in the coding sequence at two important SNPs (C606T and G612A), known to be markers for out of season breeding in sheep were studied by PCR-RFLP in a panel of four breeds of sheep from subtemperate and subtropical arid conditions, respectively. The frequencies of ‘G’ and ‘A’ alleles with reference to G612A SNP did not differ considerably among all the breeds of sheep. Frequency of ‘T’ allele of the C606T SNP was found to be dominantly higher in subtemperate sheep breeds in comparison to subtropical sheep breeds. Identified SNPs in the coding region were mostly synonymous and did not lead to any change in conformation of the MTNR1A receptor protein.     

Broad-based resistance to pigeonpea sterility mosaic disease in wild relatives of pigeonpea (Cajanus: Phaseoleae)

Sterility mosaic disease (SMD), an important biotic constraint on pigeonpea (Cajanus cajan) in the Indian subcontinent, is caused by Pigeonpea sterility mosaic virus (PPSMV) transmitted by the eriophyid mite, Aceria cajani. Distinct PPSMV isolates occur in different geographical regions and broad‐based resistance to all these isolates is scarce in cultivated pigeonpea germplasm. Wild relatives of pigeonpea, which are known to possess resistance to several pests and diseases, were evaluated for broad‐based SMD resistance. One hundred and fifteen wild Cajanus accessions from six species (C. albicans, C. platycarpus, C. cajanifolius, C. lineatus, C. scarabaeoides and C. sericeus) were evaluated against three PPSMV isolates prevailing in peninsular India. Evaluations were done under greenhouse conditions in endemic locations of each isolate through mite‐mediated virus inoculation. Fifteen accessions showed resistance to all three isolates: ICP 15614, 15615, 15626, 15684, 15688, 15700, 15701, 15725, 15734, 15736, 15737, 15740, 15924, 15925 and 15926. Most of the wild accessions did not support mite multiplication. The majority of the accessions resistant to PPSMV following inoculations with viruliferous mites were susceptible by graft inoculation, suggesting that vector resistance is conferring resistance to infection with PPSMV. The 15 accessions identified as being resistant to infection to all three virus isolates tested are cross compatible with pigeonpea by traditional breeding. They are therefore useful for exploitation in breeding programmes to increase both the level of SMD resistance and to diversify its genetic base in the cultivated pigeonpea gene pool.     

温度和光周期影响两种同域发生瓢虫同种和异种组合时的猎物消耗量和利用率（英文）

【目的】印度次大陆是世界上最脆弱的地理景观。气候条件的略微变动可能对其季节周期可能产生不良影响,并引起农业生态系统中蚜虫的大暴发。七星瓢虫Coccinella septempunctata L.和狭臀瓢虫C.transversalis Fab.是该次大陆上广泛分布、同域发生的两种食蚜性瓢虫。【方法】设计异地试验,来探究同种和/或异种组合时的这两种瓢虫用共同的猎物资源(豌豆蚜)饲养时,对增加的温度(15,20,25,30和35℃)和光周期(8L∶16D,12L∶12D和16L∶8D)的响应。【结果】结果表明,在这5个不同温度和3个不同光周期条件下,同种或异种组合时这两种瓢虫表现出了拮抗作用。尽管表现出拮抗作用,但是同种或异种组合的两捕食动物在25℃和长光周期(16L∶8D)条件下消耗、转化和利用的猎物生物量最大。然而,它们的猎物消耗率、转化效率和生长速率在异种组合中最高。在5个不同温度下,4龄幼虫均更有效地利用猎物生物量,将其转变成自身生物量,而雌成虫在3个不同光周期条件下也是如此。【结论】因此可以推断,增加的温度和光周期条件可能不会阻止同种和异种组合中的瓢虫发生拮抗作用,但是在25℃和长光周期(16L∶8D)条件下,相互作用的瓢虫的猎物消耗量和利用率为最佳。     

Endogenous Growth Substances in Normal and Dwarf Mutants of Cortland and Golden Delicious Apple Shoots

Endogenous growth substances in the shoots of dwarf mutants of Cortland (Cortland 65–6 and Cortland 65–7) and Golden Delicious (Golden Auvil Spur and Yellow Spur) were investigated in relation to dwarfism. The shoots were extracted at three stages of growth, namely: 1) rapid elongation growth, 2) formation of terminal bud, and 3) cessation of cambial growth. The growth substances were partially separated by thin layer chromatography and bioassayed using the Avena first internode and Lepidium seed germination tests. Shoot extracts from the normal Cortland and Golden Delicious plants contained higher levels of auxins at all stages of growth than those from dwarf mutants. Growth-promoting activity was found in two zones on chromatograms developed with isopropanol: ammonia: water (10:1:1 v/v/v):R_f 0.4 to 0.5 and R_f 0.8 to 0.9. The Lepidium seed germination test showed the presence of a highly inhibitory zone between R_f 0.3 and 0.4 in the extracts of dwarf and normal plants. However, the peak of germination inhibition activity was sharp for dwarf mutants and less for extracts of normal growing plants at 3 stages of growth. The inhibitory substance(s) was further purified on TLC plates by successive separations in different solvent systems. Two substances which inhibited the Lepidium seed germination were found, one close to the R_f value of synthetic abscisic acid and the other appeared to be similar to xanthoxin in R_f value, biological activity and UV absorption spectra.     

Population Analysis of Licuala glabra Griff. var. glabra (Palmae) using RAPD Profiling

Random amplified polymorphic DNA (RAPD) profiling revealed geneticdiversity among three populations ofLicuala glabra var. glabra,an understorey palm growing in the dipterocarp forests of Terengganu,Malaysia. The Bukit Bauk population had individuals withoutaerial stems. The Bukit Besi individuals had stem heights to30 cm, while those of the Rasau Kerteh population had stemsup to 4 m in height. Southern blot analysis confirmed that anapparent monomorphic band generated by the primer OPU-17 amongthe three different populations corresponds to the same locus.Six primers were used to generate 87 RAPD bands that formed2-state character raw data for estimating genetic distancesusing the simple matching coefficient of similarity. The phenogramgenerated by UPGMA of the RAPD data grouped the individualsfrom the three populations under three clusters. This was inagreement with the morphological grouping. The infraspecificL. glabra var.selangorensis Becc. was grouped closer to theL. glabra var. glabra individuals than to the outgroupL. scortechiniiBecc. Principal component analysis supported the observationfrom the phenogram. The results show discrete genetic structuringin the populations studied and provide useful information forfuture conservation measures. Copyright 1999 Annals of BotanyCompany Licuala glabra Griff. var. glabra, RAPD, palm, AMOVA, population, genetic diversity, conservation.