Characterization of messenger RNA from epimastigotes and metacyclic trypomastigotes of Trypanosoma cruzi

The cell-free translation products of polyribosomal and post-polyribosomal mRNAs from the non-infective epimastigotes and the infective metacyclic trypomastigotes of the parasitic protozoan Trypanosoma cruzi were compared by two-dimensional polyacrylamide gel electrophoresis. The result show that although many polypeptides are conserved, quantitative and qualitative differences are observed between both differentiation stages. The results also indicate the existence of post-polyribosomal mRNAs in equilibrium with polyribosomal counterparts. The immunoprecipitation of the in vitro synthesized polypeptides with chagasic human serum and the serum raised against an 85-kDa glycoprotein (P2-WGA), potentially involved in the process of T. cruzi penetration into mammalian cells, shows that while the chagasic serum recognizes the same 72-kDa, 68-kDa and 46-kDa polypeptides in both differentiation stages, the anti-P2-WGA serum immunoprecipitates a single 48-kDa polypeptide from in vitro translation products of metacyclic trypomastigotes.     

Spore age and coverslip placement affects germination and post-germination development of Colletotrichum dematium var circinans

Spore suspensions from young (10–14 da; young spores) and old (4 mo; old spores) colonies of PColletotrichum dematium var circinans were placed on slides. Coverslips were left off, placed on in the normal manner, or supported on shims. Slides were placed in moist chambers and incubated in light or dark for up to 48 hrs. Germination and post-germination development were studied. Shimming had some beneficial effect on germination, especially for old spores in dark. In general, more germ-tubes and appressoria were produced on spores under shims than spores with other coverslip treatments. By 48 hrs more old spores under shims germinated, and greater numbers of germ-tubes and appressoria were produced than on other old spores under different coverslip treatments. However, numbers produced were lower than those predicted for comparably treated young spores. Spore age, incubation regime, and placement of coverslips did not affect germ-tube initiation. For all treatments more germ-tubes were initiated from spore tops than bottoms or tips. Fewer germ-tubes were initiated from spore centers than other locations on tops and bottoms, and from both tips than one tip. Approximately 26 % of all appressoria were produced sessile. A higher percentage of sessile appressoria were produced on old spores (80 %) than on young spores (20%).     

Measurements of the specific activity of the nucleoside triphosphate pool of sea-urchin embryos following 8-3H-guanosine administration

The nucleoside triphosphate (NTP) pool during the early development of sea-urchin, Paracentrotus lividus, was measured using high-performance liquid chromatography (HPLC). Each NTP pool was measured at four stages between the eight-blastomere stage and the early blastula stage, as was the specific activity of each NTP following an initial administration of 8-3H-guanosine. Unexpectedly high UTP (uridine-5'-triphosphate) concentrations and radioactivity levels in UTP were observed. Studies of the sea-urchin, Strongilocentrotus purpuratus, also revealed elevated levels of 8-3H-guanosine incorporation into UTP. The present procedure was found to be suitable for the unequivocal identification of UTP.     

The "Alzheimer's disease signature": potential perspectives for novel biomarkers

Alzheimer's disease is a progressive and neurodegenerative disorder which involves multiple molecular mechanisms. Intense research during the last years has accumulated a large body of data and the search for sensitive and specific biomarkers has undergone a rapid evolution. However, the diagnosis remains problematic and the current tests do not accurately detect the process leading to neurodegeneration. Biomarkers discovery and validation are considered the key aspects to support clinical diagnosis and provide discriminatory power between different stages of the disorder. A considerable challenge is to integrate different types of data from new potent approach to reach a common interpretation and replicate the findings across studies and populations. Furthermore, long-term clinical follow-up and combined analysis of several biomarkers are among the most promising perspectives to diagnose and manage the disease. The present review will focus on the recent published data providing an updated overview of the main achievements in the genetic and biochemical research of the Alzheimer's disease. We also discuss the latest and most significant results that will help to define a specific disease signature whose validity might be clinically relevant for future AD diagnosis.     

GRF-induced feeding: Evidence for protein selectivity and opiate involvement

Growth hormone-releasing factor (GRF) is a hypothalamic peptide named for its ability to induce release of growth hormone from the anterior pituitary. GRF also acts as a neurotransmitter in the suprachiasmatic nucleus/medial preoptic area (SCN/MPOA) to stimulate food intake. The purpose of this series of experiments was to explore the nature of GRF-induced feeding, with a particular emphasis on macronutrient selectivity, and to examine the role of opiate activity in the paraventricular nucleus of the hypothalamus (PVN). Chow intake stimulated by GRF microinjection (1 pmol/0.5 μl) into the SCN/MPOA was blocked by injection of methyl-naltrexone (3 μg/0.5 μl) into the PVN. In animals habituated to macronutrient diets (Teklad, WI), GRF preferentially stimulated intake of protein at 2 and 4 h postinjection, whereas it had no effect on carbohydrate intake. Further, this effect was blocked by injection of naloxone (40 nmol/0.5 μl) into the PVN. Microinjection of morphine (0, 1, 10, and 17 μg/0.5 μl) into the PVN also specifically stimulated protein intake at 2 and 4 h postinjection. These results suggest that feeding derived from GRF actions in the SCN/MPOA is macronutrient selective, and is dependent on PVN opiate activity for expression.     

Alpha 1 chain of chick type VI collagen. The complete cDNA sequence reveals a hybrid molecule made of one short collagen and three von Willebrand factor type A-like domains

A cDNA library constructed from chick aorta poly(A+) RNA in the expression vector pEX1 was screened with rabbit polyclonal antisera. Additional clones were obtained by DNA-DNA hybridization with subclones from the most 5'- and 3'-ends. The overlapping clones span 4.6 kilobases and code for the entire alpha 1 (VI) chain. The nucleotide sequence reveals a 3057-base pair open reading frame that codes for 1019 amino acids. Analysis of the deduced amino acid sequence predicts that alpha 1 (VI) has one collagenous domain (COL) of 336 residues flanked by three repeated domains of about 200 residues each, one at the amino (A'3) and two at the carboxyl ends (A'2 and A'1), respectively, that are similar to the type A repeats of von Willebrand Factor. The COL domain presents two short interruptions near the carboxyl end of the triple helix and three of the six potential N-asparaginyl-linked carbohydrate attachment sites (Asn-Xaa-Ser/Thr). Furthermore, it contains 1 cysteine at position 89 that could participate in the formation of dimers and 3 Arg-Gly-Asp sequences that might be potential sites for cell adhesion. The COL domain shows an extended region, starting from position 40, within the triple helix, made of 14 Gly-Xaa-Yaa triplets that lack proline in the Y position, suggesting that it might be more flexible than the rest of the domain. At the junction of the COL with the N- and C-terminal domains, there are several cysteines that could confer the well known resistance of type VI collagen to pepsin and collagenase digestion under nonreducing conditions. The present sequence data allow a structural model for type VI collagen assembly to be proposed that is consistent with the structure implied from previous electron microscopic observation by Furthmayr et al. (Furthmayr, H., Wiedemann, H., Timpl, R., Odermatt, R., and Engel, J. (1983) Biochem. J. 221, 303-311).