Programming,induction, or prevention of the breakdown of the prothoracic gland in the cockroach, Nauphoeta cinerea

Changes of the prothoracic gland (PGL) diameter and of the corpora allata (CA) volume during the second last and last larval instar, and transplantation experiments as well as juvenile hormone (JH) analogue applications, demonstrate that only an activated PGL seems to be competent to degenerate and that the breakdown of the activated PGL is programmed by the absence of JH for a few days. Then, some days later, at the time of apolysis induction which occurs 7 to 6 days before an ecdysis the breakdown of a programmed PGL is induced by factors present in the haemolymph and it is suggested that β-ecdysone in apolysis-inducing amounts could be responsible for the induction of degeneration. However, PGL-protecting factors released probably from the corpora cardiaca (CC) are capable of partially preventing the breakdown of PGLs that have already been induced to degenerate, and it seems that the actual degeneration process is initiated by the absence of PGL-protecting factors only.     

EFFECTS OF LOW NITROGEN LEVELS AND VARIOUS NITROGEN SOURCES ON GROWTH AND WHORL DEVELOPMENT IN ACETABULARIA (CHLOROPHYTA)1

Nitrate, ammonia, urea, and glycine were compared as nitrogen sources for Acetabularia mediterranea. Cells grew normally in media containing nitrate or urea, while cells did not grow at all when the same amount of N was supplied as ammonium ion. The utilization of glycine remains questionable. Cells in medium without added N (NDM) increased in length and some formed reproductive caps. The whorls of vegetative cells showed considerable hypertrophy in NDM and in glycine. This hypertrophy was due to the elongation of only the first-(a₁) and second- (a₂) order articles. When cut, the basal portion of cells without added N regenerated new apices with whorls. The development of these whorls was inversely proportional to the NO₂ concentration. Analyses showed that the intracellular nitrogen pool in young cells and regenerating bases was very small, about 1/10 of that of fully grown cells. Therefore we suggest that trace amounts of N contaminants in the medium supported growth and development, the uptake of which was facilitated by the hypertrophied whorls, under N-limited conditions.     

The α-<Emphasis Type="SmallCaps">l</Emphasis>-fucosidase from <Emphasis Type="Italic">Sulfolobus solfataricus</Emphasis>

Glycoside hydrolases form hyperthermophilic archaea are interesting model systems for the study of catalysis at high temperatures and, at the moment, their detailed enzymological characterization is the only approach to define their role in vivo. Family 29 of glycoside hydrolases classification groups α-l-fucosidases involved in a variety of biological events in Bacteria and Eukarya. In Archaea the first α-l-fucosidase was identified in Sulfolobus solfataricus as interrupted gene expressed by programmed −1 frameshifting. In this review, we describe the identification of the catalytic residues of the archaeal enzyme, by means of the chemical rescue strategy. The intrinsic stability of the hyperthermophilic enzyme allowed the use of this method, which resulted of general applicability for β and α glycoside hydrolases. In addition, the presence in the active site of the archaeal enzyme of a triad of catalytic residues is a rather uncommon feature among the glycoside hydrolases and suggested that in family 29 slightly different catalytic machineries coexist.     

Deep Crustal Communities of the Juan de Fuca Ridge Are Governed by Mineralogy

Volcanic ocean crust contains a global chemosynthetic microbial ecosystem that impacts ocean productivity, seawater chemistry and geochemical cycling. We examined the mineralogical effect on community structure in the aquifer ecosystem by using a four-year in situ colonization experiment with igneous minerals and glasses in Integrated Ocean Drilling Program Hole 1301A on the Juan de Fuca Ridge. Microbial community analysis and scanning electron microscopy revealed that olivine phases and iron-bearing minerals bore communities that were distinct from iron-poor phases. Communities were dominated by Archaeoglobaceae, Clostridia, Thermosipho, Desulforudis and OP1 lineages. Our results suggest that mineralogy determines microbial composition in the subseafloor aquifer ecosystem.     

Antioxidant activity,acetylcholinesterase and tyrosinase inhibitory potential of Pulmonaria officinalis and Centarium umbellatum extracts

In this study several investigations and tests were performed to determine the antioxidant activity and the acetylcholinesterase and tyrosinase inhibitory potential of Pulmonaria officinalis and Centarium umbellatum aqueous extracts (10% mass) and ethanolic extracts (10% mass and 70% ethanol), respectively. Moreover, for each type of the prepared extracts of P. officinalis and of C. umbellatum the content in the biologically active compounds – polyphenols, flavones and proanthocyanidins was determined. The antioxidant activity was assessed using two methods, namely the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and reducing power assay. The analyzed plant extracts showed a high acetylcholinesterase and tyrosinase inhibitory activity in the range of 72.24–94.24% (at the highest used dose – 3 mg/mL), 66.96% and 94.03% (at 3 mg/mL), respectively correlated with a high DPPH radical inhibition – 70.29–84.9% (at 3 mg/mL). These medicinal plants could provide a potential natural source of bioactive compounds and could be beneficial to the human health, especially in the neurodegenerative disorders and as sources of natural antioxidants in food industry.     

Mast cells impair the development of protective anti-tumor immunity

Mast cells have emerged as critical intermediaries in the regulation of peripheral tolerance. Their presence in many precancerous lesions and tumors is associated with a poor prognosis, suggesting mast cells may promote an immunosuppressive tumor microenvironment and impede the development of protective anti-tumor immunity. The studies presented herein investigate how mast cells influence tumor-specific T cell responses. Male MB49 tumor cells, expressing HY antigens, induce anti-tumor IFN-??⁺ T cell responses in female mice. However, normal female mice cannot control progressive MB49 tumor growth. In contrast, mast cell-deficient c-Kit^Wsh (W^sh) female mice controlled tumor growth and exhibited enhanced survival. The role of mast cells in curtailing the development of protective immunity was shown by increased mortality in mast cell-reconstituted W^sh mice with tumors. Confirmation of enhanced immunity in female W^sh mice was provided by (1) higher frequency of tumor-specific IFN-??⁺ CD8⁺ T cells in tumor-draining lymph nodes compared with WT females and (2) significantly increased ratios of intratumoral CD4⁺ and CD8⁺ T effector cells relative to tumor cells in W^sh mice compared to WT. These studies are the first to reveal that mast cells impair both regional adaptive immune responses and responses within the tumor microenvironment to diminish protective anti-tumor immunity.     

Extracellular myocilin affects activity of human trabecular meshwork cells

The trabecular meshwork (TM), a specialized eye tissue, is a major site for regulation of the aqueous humor outflow. Malfunctioning of this tissue is believed to be responsible for development of glaucoma, a blinding disease. Myocilin is a gene linked to the most common form of glaucoma. The protein product has been localized to both intra and extracellular sites, but its function still remains unclear. This study was to determine whether extracellular myocilin presented in the matrix affects adhesion, morphology, and migratory and phagocytic activities of human TM cells in culture. Cell adhesion assays indicated that TM cells, while adhering readily on fibronectin, failed to attach on recombinant myocilin purified from bacterial cultures. Adhesion on fibronectin was also compromised by myocilin in a dose dependent manner. Myocilin in addition triggered TM cells to assume a stellate appearance with broad cell bodies and microspikes. Loss of actin stress fibers and focal adhesions was observed. TM cell migration on fibronectin/myocilin to scratched wounds was reduced compared to fibronectin controls. Myocilin, however, had little impact on phagocytic activities of TM cells. Cell attachment on fibronectin and migration of corneal fibroblasts, a control cell type, were not altered by myocilin. These results demonstrate that extracellular myocilin elicits anti-adhesive and counter-migratory effects on TM cells. Myocilin in the matrix of tissues could be exerting a similar influence on TM cells in vivo, impacting the flexibility and resilience required for maintenance of the normal aqueous outflow.     

A novel alpha-D-galactosynthase from Thermotoga maritima converts beta-D-galactopyranosyl azide to alpha-galacto-oligosaccharides

The large-scale production of oligosaccharides is a daunting task, hampering the study of the role of glycans in vivo and the testing of the efficacy of novel glycan-based drugs. Glycosynthases, mutated glycosidases that synthesize oligosaccharides in high yields, are becoming important chemo-enzymatic tools for the production of oligosaccharides. However, while β-glycosynthase can be produced with a rather well-established technology, examples of α-glycosynthases are thus far limited only to enzymes from glycoside hydrolase 29 (GH29), GH31 and GH95 families. α-L-Fucosynthases from GH29 use convenient glycosyl azide derivatives as a strategic alternative to glycosyl fluoride donors. However, the general applicability of this method to other α-glycosynthases is not trivial and remains to be confirmed. Here, β-D-galactopyranosyl azide was converted to α-galacto-oligosaccharides with good yields and high regioselectivity, catalyzed by a novel α-galactosynthase based on the GH36 α-galactosidase from the hyperthermophilic bacterium Thermotoga maritima. These results open a new avenue to the practical synthesis of biologically interesting α-galacto-oligosaccharides and demonstrate more widespread use of β-glycosyl-azide as donors, confirming their utility to expand the repertoire of glycosynthases.