Antizyme inhibitor 2: molecular, cellular and physiological aspects

Polyamines are small organic polycations essential for cell proliferation and survival. Antizymes (AZs) are small proteins regulated by polyamines that inhibit polyamine biosynthesis and uptake in mammalian cells. In addition, antizyme functions are also regulated by antizyme inhibitors, homologue proteins of ornithine decarboxylase lacking enzymatic activity. There are two antizyme inhibitors (AZIN), known as AZIN1 and AZIN2, that bind to AZs and negate their effects on polyamine metabolism. Here, we review different molecular and cellular properties of the novel AZIN2 with particular emphasis on the role that this protein may have in brain and testis physiology. Whereas AZIN1 is ubiquitously found in mammalian tissues, AZIN2 expression appears to be restricted to brain and testis. In transfected cells, AZIN2 is mainly located in the endoplasmic reticulum–Golgi intermediate compartment and in the cis-Golgi network. AZIN2 is a labile protein that is degraded by the proteasome by a ubiquitin-dependent mechanism. Regarding its physiological role, spatial and temporal analyses of AZIN2 expression in the mouse testis suggest that this protein may have a role in spermiogenesis.     

Sodium cotransport systems: cellular, molecular and regulatory aspects

The sodium cotransport systems comprise an important group of transport proteins which are involved in the transport of a variety of organic and inorganic solutes across the cellular membrane of animal cells. These systems play a central role in a wide variety of cellular and biochemical processes. We summarize here the current state of knowledge regarding the variety, structure and regulation of this important group of membrane proteins.     

Gutsy moves in mice: cellular and molecular dynamics of endoderm morphogenesis

Despite the importance of the gut and its accessory organs, our understanding of early endoderm development is still incomplete. Traditionally, endoderm has been difficult to study because of its small size and relative fragility. However, recent advances in live cell imaging technologies have dramatically expanded our understanding of this tissue, adding a new appreciation for the complex molecular and morphogenetic processes that mediate gut formation. Several spatially and molecularly distinct subpopulations have been shown to exist within the endoderm before the onset of gastrulation. Here, we review findings that have uncovered complex cell movements within the endodermal layer, before and during gastrulation, leading to the conclusion that cells from primitive endoderm contribute descendants directly to gut.     

Key aspects of the molecular and cellular basis of inhalational anthrax

Bacillus anthracis is the etiologic agent of the disease inhalational anthrax, an acute systemic infection initiated by inhaling spores, which if not rapidly detected and treated, results in death. Decades of research have elucidated novel aspects of anthrax pathogenesis but there are many issues left unresolved.     

Some aspects of infanticide and intermale competition among langurs,Presbytis entellus,at Dharwar,India

Conspecific infanticides by male langurs depresses population growth in their densely populated habitats. An infanticidal model developed from demographic parameters obtained in the Dharwar study area predicts an almost stable population. On the other hand, a non-infanticidal model predicts a population growth by 2.6% per year. The effect of frequent troop usurpation and infanticide on the control of population growth must be strong if the natality rate is high. For subadult and juvenile surplus males, it must be difficult to survive and to mature in the all-male party in its poor habitat. However, from calculations for living adult males and the number of troops at Dharwar, most adult males are thought to be able to obtain a troop within five years of first challenge of usurpation. Dominant males do not always take over a troop containing more females than do subordinate males. These simple assessments require further intensive field studies to determine the precise differences between infanticidal and non-infanticidal populations and whether or not dominant males make a greater genetic contribution than subordinate males to subsequent generations.     

Development of the embryonic segment pattern in the pea-beetle Callosobruchus maculatus. Supracellular,cellular and molecular aspects

Summary

This review deals with the question of how cells in the early embryo of the pea-beetle differentiate into a sequential pattern of segments. Anterior and posterior fragments of an egg have different options for development depending on whether they are exposed, before cellularization, to decaying ooplasm in the complementary fragment. Without such exposure all fragments produce fewer segments than corresponding fragments obtained at cellularization. With exposure a fraction of anterior and posterior fragments produces considerably more segments than corresponding fragments obtained at cellularization. In addition, posterior fragments are uniquely different from anterior ones in that they also produce reversal of segment sequence which can be restricted to longitudinal strips of the larval cuticle.

The difference in reaction to decaying ooplasm between anterior and posterior fragments suggests an asymmetry in the control of metamerization. Lateral inhibition by an asymmetric gradient of a diffusible morphogen can describe these observations [18] except for the restriction of reversal to longitudinal strips. The latter requires either that morphogen transport be polarized, possibly by a voltage gradient in the egg, or that the interpretation of cell position is polarized. The induction of double abdomens with UV-light and RNase suggests that RNA is part of the control mechanism. This and strip-restricted reversal are features shared by eggs of Coleoptera and Diptera.     

Deteriogenic cyanobacteria on historic buildings in Brazil detected by culture and molecular techniques

There are few modern analyses of the cyanobacterial communities in biofilms on external building surfaces. As the classification of cyanobacteria is rapidly changing, we aimed to identify them on historic buildings in Brazil using both established and molecular techniques. In mature biofilms, cyanobacteria of subsections I and II were generally the major biomass; occasionally filamentous genera of the Scytonemataceae, Microchaetaceae and Rivularaceae were dominant. Filamentous organisms of subsections III and IV were more frequently isolated in culture. PCR products using cyanobacteria-specific 16S rDNA primers were sequenced from morphologically identified organisms. Homologies with deposited sequences were generally low. Phylogenetic analysis showed that many isolates were distant from their nearest neighbours, even though they grouped with their appropriate taxa. The majority of cyanobacterial DNA sequences deposited in data banks are aquatic; our results indicate that cyanobacteria from external walls are an ecologically isolated group.     

The persistence of bifidobacteria populations in a river measured by molecular and culture techniques

Aims:  To determine relative to faecal coliforms (FC) and sulfite-reducing clostridia (SRC), the environmental persistence of natural populations of Bifidobacterium spp. enumerated by culturing and quantitative polymerase chain reaction (q-PCR).
Methods and Results:  Dialysis tubing containing river supplemented with overnight cultures of Bifidobacterium adolescentis (BA) and Bifidobacterium dentium (BD) or urban wastewater were suspended in a river for up to 10 days. At intervals, the contents of each dialysis tube were assayed using q-PCR assays for BA and BD, and selective culture media for FC, SRC, total bifidobacteria (TB), sorbitol-fermenting bifidobacteria (SFB) and cultivable BA. Mean summer T ₉₀ values were 251 h for SRC, 92 h for FC, 48 h for BA and BD by q-PCR, and 9 h for TB.
Conclusions:  Bifidobacterium spp. was the population with the lowest persistence, showing seasonal differences in T ₉₀ when measured by culture techniques or by q-PCR. This difference in relative persistence is because of a longer persistence of molecular targets than cultivable cells.
Significance and Impact of the Study:  The persistence of a viable bifidobacteria cells is shorter, but the longest persistence of molecular targets. This factor could be used for origin the faecal pollution in water for the development of microbial source tracking (MST).     

Cellular and molecular aspects of mouse primordial germ cell migration and proliferation in culture.

The development of mouse primordial germ cells is followed from their first appearance in the extraembryonic mesoderm of the posterior amniotic fold (7 dpc embryo) to their settlement in the genital ridges (12.5 dpc embryo). The role of fibronectin as adhesive substrate and/or in stimulating cell motility during PGC migration is discussed. Recent papers showing how PGCs migrate when cultured in vitro on cellular monolayers are reviewed. The process of PGC homing is proposed to be controlled by chemotaxis as well by developmentally regulated cell-to-cell interactions. Finally, evidence that survival and proliferation of PGCs is strictly dependent on growth factors such as LIF and MGF, and possibly on a cAMP-dependent mechanism is reported.     

Regulatory aspects of tissue donation,banking and transplantation in India

Amendments to India’s Transplantation of Human Organs Act, 1994, have established the legality of tissue donation and transplantation from deceased donors and the conditions under which they are permitted. The amended Act, now known as The Transplantation of Human Organs and Tissues Act, 1994, seeks to prevent the commercialization of tissue donation and to guarantee the safety of indigenous allografts. Registration of tissue banks, compliance with national standards and the appointment of transplant co-ordinators in hospitals registered under the Act are now mandatory. A national registry and Regional and State networks for donation and transplantation of tissues have been introduced. Despite the amendments a few anomalies of the principal Act persist as some of the differences between tissue and organ donation and transplantation have been overlooked. These include the possibility of skin donation in locations other than hospitals; the donation of medical and surgical tissue residues which does not pose any risk to the living donor; the non-requirement for compatibility between donor and recipient; the delayed time factor between tissue donation and transplantation which makes identification of a recipient at the time of donation impossible; and the easy availability of alternatives to tissues which make waiting lists redundant for many tissues. Rules for the implementation of the amended Act were framed in 2014 but like the Act must be adopted by the State health assemblies to become universally applicable in the country.     

In vitro analysis of cellular metaplasia from pigmented epithelial cells to lens phenotypes: a unique model system for studying cellular and molecular mechanisms of transdifferentiation

Pigmented epithelial cells (PECs) were dissociated from eyes of 8- to 9-day-old chick embryos and were cultured in EdF medium (Eagle's MEM supplemented with dialyzed fetal bovine serum) containing phenylthiourea (PTU) and testicular hyaluronidase (HUase). The PECs rapidly lost melanosomes as they proliferated and dedifferentiated in culture. These dedifferentiated PECs (dePECs) which did not manifest any identifiable specificity could be directed to one of two different differentiated phenotypes; viz., lens or pigment cells, depending upon subsequent culture conditions. Almost all dePECs began to synthesize melanin and redifferentiated to PECs by Day 10 of culture with EdF medium containing ascorbic acid (AsA). In contrast, the sister population of dePECs, when cultured at extremely high cell density with EdF medium containing PTU, HUase and AsA, synthesized delta-crystallin which is specific for lens. This transdifferentiation into lens cells occurred by Day 15 of culture. Using this culture system we are able to produce a homogeneous cell population with the potential for synchronous differentiation into either lens or pigment cell phenotype. The system is useful for studying mechanisms involved in cellular metaplasia.