The role of introns in the conservation of the metabolic genes of Arabidopsis thaliana

In Arabidopsis thaliana, primary metabolic genes (PMGs) are more evolutionarily conserved and intron-rich than secondary metabolic genes. We observed that PMGs are more primitive and pan-taxonomically persistent as compared to secondary (SMGs) and non-metabolic genes (NMGs). This difference in primitiveness and persistence is primarily correlated with intron number and is independent of gene expression level. We propose a twofold explanation behind higher intron enrichment in PMGs. Firstly, introns might increase protein versatility amongst PMGs through alternative splicing, providing selective advantage of PMGs and making them more persistent across diverse plant taxa. Also, multifunctional PMGs may acquire functional domains by increasing the intronic burden. Additionally, single nucleotide polymorphisms (SNPs) accumulate at a higher rate in introns as compared to exons. Moreover, a strong negative correlation between cumulative exonic SNPs density and intron number indicates that introns may protect the exonic regions against the deleterious effect of these mutations, making them more conserved.     

Length–weight relationships for four mullets from the Chilika lagoon,East coast of India

Current study provides information on Length–weight relationship (LWR) of four fish species of family Mugilidae i.e., Planiliza macrolepis (Smith, 1846), Chelon parsia (Hamilton, 1822), Osteomugil cunnesius (Valenciennes, 1836) and Valamugil speigleri (Bleeker, 1858) from Chilika Lagoon, East coast of India. Samples were collected during monsoon (July 2016), winter (November 2016) and summer (April 2017) seasons from the fisher's boats inside the lagoon while fishing with screen barrier nets (mesh size 18‐38 mm) and gill nets (mesh size 34, 38, 46, 62 and 86 mm). The b values were determined from the data set in LWRs as 2.958 for P. macrolepis, 2.952 for O. cunnesius and 2.919 for C. parsia and 2.883 for V. peigleri. In all species, regression values were statistically significant (p < .05).     

Effect of various organic compounds on synthesis of glucoamylase by an isolated strain Penicillium italicum

Yeast extract (0.5%) stimulates the production of glucoamylase and cell synthesis while methylene blue (0.1 mM) activates the synthesis of glucoamylase. Studies on the metabolic changes during fermentation of glucoamylase in a selected medium by P. italicum show that the rate of production of glucoamylase and cellular growth are greatly accelerated between 48 and 168 hr. Rapid growth of cells during this period may account for enhanced utilization of maltose and NH4NO3 from the medium. The acid production remains constant from 48 to 144 hr. Different forms of nitrogen decrease steadily. Although methylene blue stimulates the production of glucoamylase in the broth it has practically no effect on the rate of utilization of amino and total nitrogen from the broth.     

PGM1 subtype polymorphism in 14 endogamous Dravidian-speaking populations of South India

Red cell hemolysates from 1,004 persons belonging to 14 population groups drawn from four South Indian states, Andhra Pradesh, Tamil Nadu, Karnataka, and Kerala, were tested for PGM1 subtypes. The groups are characterized by a high frequency of phenotype 1+1+ (range 36.98-71.64%) and the allele 1+ (range 60-79%). The groups exhibit marked heterogeneity for PGM1 locus. The results show a clear demarcation between tribes and Brahmin groups.     

Identification and characterization of a Mg+2-dependent and an independent Ca+2-ATPase in microsomal membranes of rat testis

Rat testicular microsomal membrane fraction contains both Mg⁺²-dependent and Mg⁺²-independent Ca⁺²-ATPase activity. The latter activity is about two times higher than the former. Calcium ion required for maximum activation of Mg⁺²-independent Ca⁺²-ATPase in 3.0 mM, whereas for the dependent one it is 2.5 mM. Both the enzymes are resistant to cold shock upto seven days. Histidine and imidazole buffers are found to be the most suitable for dependent and independent enzyme activities, respectively. The pH optima for dependent one is 7.5, whereas for the independent one it is 8.5. Temperature optima for the former is 37°C and for latter one it is 40°C. Among all the nuclestides tested, ATP is found to be the best substrate for both the enzymes. The optimum concentration of ATP for dependent and independent enzyme activities are 3.0 mM and 1.5 mM respectively. Divalent metal ions like Zn⁺², Ba⁺² and Mn⁺² have been found to inhibit Mg⁺²-dependent Ca⁺²-ATPase activity whereas Mg⁺²-independent Ca⁺²-ATPase activity is inhibited by the divalent ions except zinc which is found to stimulate the enzyme activity. Both the enzymes are inhibited by vanadata, EDTA and EGTA. I₅₀, for vanadate is 0.05 and 0.125 mM for dependent and independent activities, respectively. Sulfhydral groups modifying agents e.g., NEM, DTNB and chlorpromazine are found to affect the enzyme activities in different ways. Thus NEM and chlorpromazine are found to inhibit and DTNB stimulate the enzyme activities in both the cases.     

Leishmania donovani: role of microviscosity of macrophage membrane in the process of parasite attachment and internalization

Host macrophage infection by the parasite Leishmania donovani is heterogeneous, but it is not clear which factors are responsible for parasite recognition within the macrophages. One possible factor may be the alteration of the microviscosity of the macrophage membrane. This in turn may affect receptor expression and hence parasite infection. In this paper we describe alteration of the lipid composition and hence the microviscosity of the macrophage membrane in a controlled manner using liposome fusion technique. At a higher macrophage membrane microviscosity a larger number of parasites have been found to adhere to the macrophage surface. However, the proportion of parasites finally internalized when compared to parasites adhering to macrophages is inversely correlated with the artificially altered macrophage membrane microviscosity. The process of endocytosis has been examined in both native and lipid modified macrophages in the presence of several sugar antagonists. The results indicate (i) glucose and mannose are specifically involved in the binding process, and (ii) the microviscosity has a key role in controlling the macrophage parasite interaction. The results obtained so far support a model of endocytosis where expression of the receptor is a critical initial process dependent on the microviscosity of the membrane.     

Increase of the peroxidase activity of mouse submaxillary gland by reserpine

The peroxidase activity of mouse submaxillary gland was found to be elevated by about 128% at 22 hr. after the administration of reserpine (0.5 mg/kg). This effect of reserpine was observed in rat also. Neither pretreatment with 6-hydroxy dopamine (6-OH dopamine) nor surgical sympathetic denervation could abolish the increase of the peroxidase activity elicited by reserpine. Also, treatment with propranolol, dibenamine or atropine sulfate failed to reverse the effect of reserpine. These results suggest that neither catecholamine nor acetyl choline is involved in this reserpine action.     

Aggregation and fusion of unilamellar vesicles by poly(ethylene glycol)

Various aspects of the interaction between the fusogen, poly(ethylene glycol) and phospholipids were examined. The aggregation and fusion of small unilamellar vesicles of egg phosphatidylcholine (PC), bovine brain phosphatidylserine (PS) and dimyristoylphosphatidylcholine (DMPC) were studied by dynamic light scattering, electron microscopy and NMR. The fusion efficiency of Dextran, glycerol, sucrose and poly(ethylene glycol) of different molecular weights were compared. Lower molecular weight poly(ethylene glycol) are less efficient with respect to both aggregation and fusion. The purity of poly(ethylene glycol) does not affect its fusion efficiency. Dehydrating agents, such as Dextran, glycerol and sucrose, do not induce fusion. 31P-NMR results revealed a restriction in the phospholipid motion by poly(ethylene glycol) greater than that by glycerol and Dextran of similar viscosity and dehydrating capacity. This may be associated with the binding of poly(ethylene glycol) to egg PC, with a binding capacity of 1 mol of poly(ethylene glycol) to 12 mol of lipid. Fusion is greatly enhanced below the phase transition for DMPC, with extensive fusion occurring below 6% poly(ethylene glycol). Fusion of PS small unilamellar vesicles depends critically on the presence of cations. Large unilamellar vesicles were found to fuse less readily than small unilamellar vesicles. The results suggest that defects in the bilayer plays an important role in membrane fusion, and the 'rigidization' of the phospholipid molecules facilitates fusion possibly through the creation of defects along domain boundaries. Vesicle aggregation caused by dehydration and surface charge neutralization is a necessary but not a sufficient condition for fusion.