pp 221-226 Brief communication
The micro-eukaryotic diversity from the human gut was investigated using universal primers directed towards 18S rRNA gene, fecal samples being the source of DNA. The subjects in this study included two breast-fed and two formula-milk-fed infants and their mothers. The study revealed that the infants did not seem to harbour any micro-eukaryotes in their gut. In contrast, there were distinct eukaryotic microbiota present in the mothers. The investigation is the first of its kind in the comparative study of the human feces to reveal the presence of micro-eukaryotic diversity variance in infants and adults from the Indian subcontinent. The micro-eukaryotes encountered during the investigation include known gut colonizers like Blastocystis and some fungi species. Some of these micro-eukaryotes have been speculated to be involved in clinical manifestations of various diseases. The study is an attempt to highlight the importance of micro-eukaryotes in the human gut.
pp 227-232 Brief communication
Neuropeptide Y (NPY) is considered the major stimulant for food intake in mammals and fish. Previous results indicate that NPY is involved in the feeding behaviour of the Brazilian flounder, Paralichthys orbignyanus. In this study, we evaluated hypothalamic NPY expression before (−2 h), during (0 h) and after feeding (+2 h) in two independent experiments: (1) during a normal feeding schedule and (2) in fish fasted for 2 weeks. During normal feeding, changes in the levels of NPY mRNA were periprandial, with expression levels being significantly elevated at meal time (𝑃 < 0.05) and significantly reduced 2 h later (𝑃< 0.05). Comparing the fasting and unfasted groups, NPY mRNA levels were significantly higher (𝑃 < 0.05) at −2 h and +2 h in the fasting group, but there was no difference at 0 h. In addition, the higher NPY mRNA levels that were observed in the fasting group were maintained throughout the sampling period. In summary, our results show that NPY expression was associated with meal time (0 h) in food intake regulation.
pp 233-241 Articles
Locked nucleic acid (LNA) and 2′-𝑂-methyl nucleotide (OMeN) are the most extensively studied nucleotide analogues. Although both LNA and OMeN are characterized by the C3′-endo sugar pucker conformation, which is dominant in A-form DNA and RNA nucleotides, they demonstrate different binding behaviours. Previous studies have focused attention on their properties of duplex stabilities, hybridization kinetics and resistance against nuclease digestion; however, their ability to discriminate mismatched hybridizations has been explored much less. In this study, LNA- and OMeN-modified oligonucleotide probes have been prepared and their effects on the DNA duplex stability have been examined: LNA modifications can enhance the duplex stability, whereas OMeN modifications reduce the duplex stability. Next, we studied how the LNA:DNA and OMeN:DNA mismatches reduced the duplex stability. Melting temperature measurement showed that different LNA:DNA or OMeN:DNA mismatches indeed influence the duplex stability differently. LNA purines can discriminate LNA:DNA mismatches more effectively than LNA pyrimidines as well as DNA nucleotides. Furthermore, we designed five LNA- and five OMeN-modified oligonucleotide probes to simulate realistic situations where target–probe duplexes contain a complementary LNA:DNA or OMeN:DNA base pairs and a DNA:DNA mismatch simultaneously. The measured collective effect showed that the duplex stability was enhanced by the complementary LNA:DNA base pair but decreased by the DNA:DNA mismatch in a position-dependent manner regardless of the chemical identity and position of the complementary LNA:DNA base pair. On the other hand, the OMeN-modified probes also showed that the duplex stability was reduced by both the OMeN modification and the OMeN:DNA mismatch in a position-dependent manner.
pp 243-257 Articles
Of all the causes identified for the disease hyper-immunoglobulinemia E syndrome (HIES), a homozygous mutation in tyrosine kinase2 (TYK2) and heterozygous mutations in STAT3 are implicated the defects in Jak/STAT signalling pathway in the pathogenesis of HIES. Mutations of STAT3 have been frequently clinically identified in autosomal-dominant (AD) HIES patients’ cells, and therefore, the genotype of STAT3 has been associated with the phenotype of HIES. Here, we conducted studies on the functional loss of the seven specific STAT3 mutations correlated with ADHIES. Using STAT3-null human colon carcinoma cell line A4 cells, we generated seven mutants of STAT3 bearing single mutations clinically identified in AD-HIES patients’ cells and studied the functional loss of these mutants in IL-6-Jak/STAT3 signalling pathway. Our results show that five STAT3 mutants bearing mutations in the DNA-binding domain maintain the phosphorylation of Tyr705 and the ability of dimerization while the other two with mutations in SH2 domain are devoid of the phosphorylation of Try705 and abrogate the dimerization in response to IL-6. The phosphorylation of Ser727 in these mutants shows diversity in response to IL-6. These mutations eventually converge on the abnormalities of the IL-6/Gp130/Jak2-mediated STAT3 transactivation on target genes, indicative of the dysregulation of JAK/STAT signalling present in HIES.
pp 259-267 Articles
The level of 𝛽-galactoside 𝛼2,6-sialyltransferase I (ST6Gal I) mRNA, encoded by the gene siat1, is increased in malignant tissues. Expression is regulated by different promoters – P1, P2 and P3 – generating three mRNA isoforms H, X and YZ. In cervical cancer tissue the mRNA isoform H, which results from P1 promoter activity, is increased. To study the regulation of P1 promoter, different constructs from P1 promoter were evaluated by luciferase assays in cervical and hepatic cell lines. Deletion of a fragment of 1048 bp (−89 to +24 bp) increased 5- and 3-fold the promoter activity in C33A and HepG2 cell lines, respectively. The minimal region with promoter activity was a 37 bp fragment in C33A cells. The activity of this region does not require the presence of an initiator sequence. In HepG2 cells the minimal promoter activity was detected in the 66 bp fragment. Sp1 (−32) mutation increased the promoter activity only in HepG2 cells. HNF1 mutation decreased promoter activity in HepG2 cell line but not in C33A cells. We identified a large region that plays a negative regulation role. The regulation of promoter activity is cell type specific. Our study provides new insights into the complex transcriptional regulation of siat1 gene.
pp 269-276 Articles
Acacia nilotica proteinase inhibitor (AnPI) was isolated by ammonium sulphate precipitation followed by chromatography on DEAE-Sephadex A-25 and resulted in a purification of 10.68-fold with a 19.5% yield. Electrophoretic analysis of purified AnPI protein resolved into a single band with molecular weight of approximately 18.6+1.00 kDa. AnPI had high stability at different pH values (2.0 to 10.0) except at pH 5.0 and are thermolabile beyond 80°C for 10 min. AnPI exhibited effective against total proteolytic activity and trypsin-like activity, but did not show any inhibitory effect on chymotrypsin activity of midgut of Helicoverpa armigera. The inhibition kinetics studies against H. armigera gut trypsin are of non-competitive type. AnPI had low affinity for H. armigera gut trypsin when compared to SBTI. The partially purified and purified PI proteins-incorporated test diets showed significant reduction in mean larval and pupal weight of H. armigera. The results provide important clues in designing strategies by using the proteinase inhibitors (PIs) from the A. nilotica that can be expressed in genetically engineered plants to confer resistance to H. armigera.
pp 277-287 Articles
The goal of the present study is to elucidate the mechanism of quercetin on modulating Naja naja atra phospholipase A2 (PLA2) activities. Sphingomyelin inhibited PLA2 enzymatic activity and membrane-damaging activity against egg yolk phosphatidylcholine (EYPC), while cholesterol and quercetin abrogated the sphingomeyelin inhibitory effect. Quercetin incorporation led to a reduction in PLA2 enzymatic activity and membrane-damaging activity toward EYPC/sphingomyelin/cholesterol vesicles. Both cholesterol and quercetin increased detergent resistance and reduced membrane fluidity of EYPC/sphingomyelin vesicles. Quercetin reduced detergent insolubility but increased ordered lipid packing of EYPC/sphingomyelin/cholesterol vesicles. Acrylamide quenching studies and trinitrophenylation of Lys residues revealed that quercetin altered the membrane-bound mode of PLA2 differently upon absorption onto the membrane bilayers of different lipid compositions. However, 8-anilinonaphthalene sulphonate-binding assay revealed that quercetin marginally affected the interaction between active site of PLA2 with phospholipid vesicles. Collectively, our data indicate that membrane-inserted quercetin modulates PLA2 interfacial activity and membrane-damaging activity via its effects on membrane structure and membrane-bound mode of PLA2.
pp 289-294 Mini-review
pp 295-300 Review
Eisosomes, large protein complexes that are predominantly composed of BAR-domain-containing proteins Pil1 and its homologs, are situated under the plasma membrane of ascomycetes. A successful targeting of Pil1 onto the future site of eisosome accompanies maturation of eisosome. During or after recruitment, Pil1 undergoes self-assembly into filaments that can serve as scaffolds to induce membrane furrows or invaginations. Although a consequence of the invagination is likely to redistribute particular proteins and lipids to a different location, the precise physiological role of membrane invagination and eisosome assembly awaits further investigation. The present review summarizes recent research findings within the field regarding the detailed structural and functional significance of Pil1 on eisosome organization.
pp 301-312 Review
It has been estimated that 1011–1012 cells, primarily of haematogenous origin, die in the adult human body daily, and a similar number is regenerated to maintain homeostasis. Despite the presence of an efficient scavenging system for dead cells, considerable amounts of fragmented genetic material enter the circulation in healthy individuals. Elevated blood levels of extracellular nucleic acids have been reported in various disease conditions; such as ageing and age-related degenerative disorders, cancer; acute and chronic inflammatory conditions, severe trauma and autoimmune disorders. In addition to genomic DNA and nucleosomes, mitochondrial DNA is also found in circulation, as are RNA and microRNA. There is extensive literature that suggests that extraneously added nucleic acids have biological actions. They can enter into cells in vitro and in vivo and induce genetic transformation and cellular and chromosomal damage; and experimentally added nucleic acids are capable of activating both innate and adaptive immune systems and inducing a sterile inflammatory response. The possibility as to whether circulating nucleic acids may, likewise, have biological activities has not been explored. In this review we raise the question as to whether circulating nucleic acids may have damaging effects on the host and be implicated in ageing and diverse acute and chronic human pathologies.
pp 313-325 Review
Pyrroloquinoline-quinine (PQQ) was initially characterized as a redox cofactor for membrane-bound dehydrogenases in the bacterial system. Subsequently, PQQ was shown to be an antioxidant protecting the living cells from oxidative damage in vivo and the biomolecules from artificially produced reaction oxygen species in vitro. The presence of PQQ has been documented from different biological samples. It functions as a nutrient and vitamin for supporting the growth and protection of living cells under stress. Recently, the role of PQQ has also been shown as a bio-control agent for plant fungal pathogens, an inducer for proteins kinases involved in cellular differentiation of mammalian cells and as a redox sensor leading to development of biosensor. Recent reviews published on PQQ and enzymes requiring this cofactor have brought forth the case specific roles of PQQ. This review covers the comprehensive information on various aspects of PQQ known till date. These include the roles of PQQ in the regulation of cellular growth and differentiation in mammalian system, as a nutrient and vitamin in stress tolerance, in crop productivity through increasing the availability of insoluble phosphate and as a bio-control agent, and as a redox agent leading to the biosensor development. Most recent findings correlating the exceptionally high redox recycling ability of PQQ to its potential as anti-neurodegenerative, anticancer and pharmacological agents, and as a signalling molecule have been distinctly brought out. This review discusses different findings suggesting the versatility in PQQ functions and provides the most plausible intellectual basis to the ubiquitous roles of this compound in a large number of biological processes, as a nutrient and a perspective vitamin.
pp 327-348 Review
Lysozymes are antibacterial enzymes widely distributed among organisms. Within the animal kingdom, mainly three major lysozyme types occur. Chicken (c)-type lysozyme and goose (g)-type lysozyme are predominantly, but not exclusively, found in vertebrate animals, while the invertebrate (i)-type lysozyme is typical for invertebrate organisms, and hence its name. Since their discovery in 1975, numerous research articles report on the identification of i-type lysozymes in a variety of invertebrate phyla. This review describes the current knowledge on i-type lysozymes, outlining their distribution, molecular mechanism and in vivo function taking the representative from Venerupis philippinarum (formerly Tapes japonica) (Vp-ilys) as a model. In addition, invertebrate g-type and ch-type (chalaropsis) lysozymes, which have been described in molluscs and nematodes, respectively, are also briefly discussed.
pp 349-358 Review
Mammary gland stem cells (MaSC) have not been identified in spite of extensive research spanning over several decades. This has been primarily due to the complexity of mammary gland structure and its development, cell heterogeneity in the mammary gland and the insufficient knowledge about MaSC markers. At present, Lin–CD29hiCD49fhiCD24+/modSca-1– cells of the mammary gland have been reported to be enriched with MaSCs. We suggest that the inclusion of stem cell markers like Oct4, Sox2, Nanog and the mammary gland differentiation marker BRCA-1 may further narrow down the search for MaSCs. In addition, we have discussed some of the other unresolved puzzles on the mammary gland stem cells, such as their similarities and/or differences with mammary cancer stem cells, use of milk as source of mammary stem cells and the possibility of in vitro differentiation of embryonic stem (ES) cells into functional mammary gland structures in this review. Nevertheless, it is the lack of identity for a MaSC that is curtailing the advances in some of the above and other related areas.
pp 359-374 Review
The origin of premating reproductive isolation continues to help elucidate the process of speciation and is the central event in the evolution of biological species. Therefore, during the process of species formation the diverging populations must acquire some means of reproductive isolation so that the genes from one gene pool are prevented from dispersing freely into a foreign gene pool. In the genus Drosophila, the phenomenon of behavioural reproductive isolation, which is an important type of premating (prezygotic) reproductive isolating mechanisms, has been extensively studied and interesting data have been documented. In many cases incomplete sexual isolation has been observed and the pattern and degree of isolation within and between the species have often been used to elucidate the phylogenetic relationships. The present review documents an overview of speciation mediated through behavioural incompatibility in different species groups of Drosophila with particular reference to the models proposed on the basis of one-sided ethological isolation to predict the direction of evolution. This study is crucial for understanding the mechanism of speciation through behavioural incompatibility and also for an understanding of speciation genetics in future prospects.
Volume 42 | Issue 4