The regulation of''early'' enzymes during the development and dedifferentiation of Dictyostelium discoideum

The specific activities of the enzymes alpha-mannosidase and N-acetylglucosaminidase increase immediately after the initiation of the development of bacterially grown cell cultures of Dictyostelium discoideum. The regulation of these two enzymes was found to be dissociable in the developmental timer mutant, FM-1, which aggregates 4.5 h earlier than wild-type cells due to the absence of the first rate-limiting component of the preaggregative period. The increase in alpha-mannosidase activity occurs in the absence of the first rate-limiting component, but the increase in N-acetylglucosaminidase activity does not. These results indicate the following: (1) the increase in the specific activity of alpha-mannosidase is not related to the timing of subsequent developmental stages; (2) the increase in the specific activity of N-acetylglucosaminidase is not necessary for the subsequent developmental program; and (3) either the increase in the specific activity of N-acetylglucosaminidase is dependent upon progress through the first rate-limiting component, or the increase in this enzyme activity and the first rate-limiting component are both dependent upon an early event for which FM-1 is defective. In addition to early development, we monitored the two enzyme activities during dedifferentiation. The results demonstrate that there is no difference between dedifferentiating wild-type cells and dedifferentiation-defective mutant HI-4 cells. Changes in enzyme specific activity accompanying dedifferentiation are dependent upon the composition of the dedifferentiation-inducing media and are consistent with the levels of these enzymes observed in cells growing in the different nutrient media.     

A study on the rate of water transport of the clam katelysia opima in relation to environmental conditions

1. The neutral red technique was employed to study the rate of filtration in Katelysia opima.
2. The weight specific water filtration was found to be greater for younger clams compared to the older ones.
3. The rate of water filtration increased with decreasing salinity.
4. Water filtration was found to increase as temperature increased, reaching a maximum at 35°C. but then sharply decreasing at 39°C.
5. Light had no significant effect on the rate of filtration.
6. Suspended matter was found to affect the rate of water filtration.
7. The rate of filtration was low at high pH and high in low pH.
8. The rate of water filtration was found to be faster during high tide than during low tide.
9. The presence of the parasitic crab, Pennotheris sp., in the mantle cavity of clams had a marked effect on the particle filtration.
10. Accidental cut of the siphon tips had no effect on the rate of filtration.

     

Understanding the binding interaction between phenyl boronic acid P1 and sugars: determination of association and dissociation constants using S–V plots,steady‐state spectroscopic methods and molecular docking

Continuous monitoring of glucose and sugar sensing plays a vital role in diabetes control. The drawbacks of the present enzyme‐based sugar sensors have encouraged the investigation into alternate approaches to design new sensors. The popularity of fluorescence sensors is due to their ability to bind reversibly to compounds containing diol. In this study we investigated the binding ability of phenyl boronic acid P1 for monosaccharides and disaccharides (sugars) in aqueous medium at physiological pH 7.4 using steady‐state fluorescence and absorbance. P1 fluorescence was quenched due to formation of esters with sugars. Absorbance and fluorescence measurements led to results that indicated that the sugars studied could be ordered in terms of their affinity to P1, as stated: sucrose > lactose > galactose > xylose > ribose > arabinose. In each case, the slope of modified Stern–Volmer plots was nearly 1, indicating the presence of only a single binding site in boronic acids for sugars. Docking studies were carried out using Schrodinger Maestro v.11.2 software. The binding affinity of phenyl boronic acid P1 with periplasmic protein (PDB ID 2IPM and 2IPL) was estimated using GlideScore.     

Developing Transgenic Jatropha Using the SbNHX1 Gene from an Extreme Halophyte for Cultivation in Saline Wasteland

Jatropha is an important second-generation biofuel plant. Salinity is a major factor adversely impacting the growth and yield of several plants including Jatropha. SbNHX1 is a vacuolar Na⁺/H⁺ antiporter gene that compartmentalises excess Na⁺ ions into the vacuole and maintains ion homeostasis. We have previously cloned and characterised the SbNHX1 gene from an extreme halophyte, Salicornia brachiata. Transgenic plants of Jatropha curcas with the SbNHX1 gene were developed using microprojectile bombardment mediated transformation. Integration of the transgene was confirmed by PCR and Rt-PCR and the copy number was determined by real time qPCR. The present study of engineering salt tolerance in Jatropha is the first report to date. Salt tolerance of the transgenic lines JL2, JL8 and JL19 was confirmed by leaf senescence assay, chlorophyll estimation, plant growth, ion content, electrolyte leakage and malondialdehyde (MDA) content analysis. Transgenic lines showed better salt tolerance than WT up to 200 mM NaCl. Imparting salt tolerance to Jatropha using the SbNHX1 gene may open up the possibility of cultivating it in marginal salty land, releasing arable land presently under Jatropha cultivation for agriculture purposes. Apart from this, transgenic Jatropha can be cultivated with brackish water, opening up the possibility of sustainable cultivation of this biofuel plant in salty coastal areas.     

A study of extracellular alkaline protease from Bacillus subtilis NCIM 2713

An alkaline protease was isolated from culture filtrate of B. subtilis NCIM 2713 by ammonium sulphate precipitation and was purified by gel filtration. With casein as a substrate, the proteolytic activity of the purified protease was found to be optimal at pH 8.0 and temperature 70 degrees C. The purified protease had molecular weight 20 kDa, Isoelectric point 5.2 and km 2.5 mg ml(-1). The enzyme was stable over the pH range 6.5-9.0 at 37 degrees C for 3 hr. During chromatographic separation this protease was found to be susceptible to autolytic degradation in the absence of Ca2+. Ca2+ was not only required for the enzyme activity but also for the stability of the enzyme above 50 degrees C. About 62% activity was retained after 60 min at pH 8.0 and 55 degrees C. DFP and PMSF completely inhibited the activity of this enzyme, while in the presence of EDTA only 33% activity remained. However, it was not affected either by sulfhydryl reagent, or by divalent metal cations, except SDS and Hg2+. The results indicated that this is a serine protease.     

Value-added food: single cell protein

The alarming rate of population growth has increased the demand for food production in third-world countries leading to a yawning gap in demand and supply. This has led to an increase in the number of hungry and chronically malnourished people. This situation has created a demand for the formulation of innovative and alternative proteinaceous food sources. Single cell protein (SCP) production is a major step in this direction. SCP is the protein extracted from cultivated microbial biomass. It can be used for protein supplementation of a staple diet by replacing costly conventional sources like soymeal and fishmeal to alleviate the problem of protein scarcity. Moreover, bioconversion of agricultural and industrial wastes to protein-rich food and fodder stocks has an additional benefit of making the final product cheaper. This would also offset the negative cost value of wastes used as substrate to yield SCP. Further, it would make food production less dependent upon land and relieve the pressure on agriculture. This article reviews diversified aspects of SCP as an alternative protein-supplementing source. Various potential strains and substrates that could be utilized for SCP production are described. Nutritive value and removal of nucleic acids and toxins from SCP as a protein-supplementing source are discussed. New processes need to be exploited to improve yield. In that direction the solid state fermentation (SSF) method and its advantages for SCP production are highlighted.     

Modern pollen rain from the Biligirirangan-Melagiri hills of southern Eastern Ghats, India

A total of 39 soil surface samples collected between 11 degrees 30'N 76 degrees 45'E and 12 degrees 45'N 78 degrees 15'E from the mainly deciduous forests in the Biligirirangan-Melagiri hills of the southern Eastern Ghats were analysed for their pollen content. The samples are distributed among four different deciduous and evergreen vegetation types between 210 and 1700m altitudes and fall within three distinct rainfall regimes. The aims of this paper are to provide new data on the modern pollen rain from the Southern Eastern Ghats, a region characterized by a unique and complex climate and vegetation, and to interpret these data using multivariate statistics and the diagram of pollen percentages. We could distinguish first between the deciduous and the evergreen forests and then also between different types of deciduous forest. The distinction between the evergreen and deciduous forests was based on a humidity gradient and that among the deciduous forests on a physiognomic gradient identified through correspondence analysis. The above analysis also allowed us to identify a set of 14 pollen taxa markers and 11 associated pollen taxa that help differentiate the evergreen from deciduous forests. Similarly, a set of 12 pollen taxa markers and six associated pollen taxa was demarcated to help distinguish woodland formations from scrub and thicket formations, among the deciduous vegetation. We could also differentiate amongst the four distinct vegetation types sampled, on the basis of distinct associations of both tree and herb pollen taxa according to their relative abundance in the pollen diagram as well as on the proportion of total arboreal pollen. The ground cover of grasses and other herbaceous plants in the deciduous forests is effectively demonstrated by percentages of non-arboreal pollen varying between 40 and 70%. The 1000m altitude limit reflecting a gradient of humidity and the physiognomic gradient among deciduous forests seem to be important in this region.     

Environmental Quality Assessment of Bizerte Lagoon (Tunisia) Using Living Foraminifera Assemblages and a Multiproxy Approach

This study investigated the environmental quality of the Bizerte Lagoon (Tunisia) through an integrated approach that combined environmental, biogeochemical, and living benthic foraminiferal analyses. Specifically, we analyzed the physicochemical parameters of the water and sediment. The textural, mineralogical, and geochemical characteristics of the sediment, including total organic carbon, total nitrogen, simultaneously extracted metals (SEM), acid volatile sulfides (AVS), chlorophyll a, CaCO₃, and changes in bacterial populations and carbon isotopes were measured. The SEM/AVS values indicated the presence of relatively high concentrations of toxic metals in only some areas. Foraminiferal assemblages were dominated by species such as A. parkinsoniana (20–91%), Bolivina striatula (<40%), Hopkinsina atlantica (<17%), and Bolivina ordinaria (<15%) that cannot be considered typical of impacted coastal lagoons both in Mediterranean and northeast Atlantic regions. The results of this work suggest that Bizerte Lagoon is a unique setting. This lagoon is populated by typical marine species that invaded this ecosystem, attracted not only by the prevailing favorable environmental conditions but also by the abundance and quality of food. The results indicate that the metal pollution found in some areas have a negative impact on the assemblages of foraminifera. At present, however, this negative impact is not highly alarming.