Evidence for Regular Sporulation by Haplosporidium nelsoni (MSX) (Ascetospora; Haplosporidiidae) in Spat of the American Oyster, Crassostrea virginica

The spore stage of Haplosporidium nelsoni , the ascetosporan parasite causing multinucleated sphere unknown (MSX) disease in oysters, Crassostrea virginica , has been reported so rarely (≥0.01% of infected oysters) that a second host has been postulated. However, recent intensive sampling of young (≥1 year) oysters in Delaware Bay, U.S. suggests that spore formation occurs regularly in this group and that spores are produced in at least 75–85% of all infections reaching the advanced stage. Sporulation was seasonal, occurring over two to three weeks in late June/early July and again in late summer/early fall. Our data indicate that sporulation by H. nelsoni in oysters is more common than previously suspected, occurring in a segment of the host population that may not have been sufficiently sampled in the past, and that a direct life cycle should be reconsidered.     

Transport of purines and pyrimidines into isolated pea chloroplasts

Abstract. Uptake of [¹⁴C] adenine and [¹⁴C] cytosine into isolated pea chloroplasts has been examined by using a centrifugal-filtration technique. These chloroplasts accumulate both compounds in the sucrose-impermeable space to concentrations higher than that present in the external solution when the latter was below 1.0 mM. Competition experiments suggested that uptake is mediated by a carrier mechanism.     

Enzymatic Basis for Platelet: Collagen Adhesion as the Primary Step in Haemostasis

The formation of an enzyme-acceptor complex as the effective intermediate in platelet: collagen adhesion provides a simple model for studying the primary step in haemostasis and may provide a rational basis for the design of anti-thrombogenic drugs.     

The Absorption of Silica from Aqueous Solutions by Plants

Silica dissolves in water to a small extent and below pH7 existsin solution essentially in a non-polar form. In this respectit contrasts with nutrient cations and anions and a study ofits uptake by plants was thought to be of interest. It was foundthat in common with the absorption of ionized solutes the entryof silica into plants appears to require the expenditure ofmetabolic energy since the process is sensitive to both metabolicinhibitors and variations in temperature. Furthermore, exceptunder conditions of very low humidity, silica enters barleyplants at a relatively greater rate than the water lost in transpiration,and its concentration in the xylem sap of bean plants may begreater than that in the external solution.     

A technique for the rapid extraction of microalgal DNA from single live and preserved cells

Molecular methods are increasingly being used in the study of harmful microalgae; however, DNA extraction techniques have imposed limitations on the species and questions studied, with research primarily restricted to cultured specimens. Here we describe a simple method that merges two existing techniques for DNA extraction from live and preserved single dinoflagellate cells. DNA was successfully isolated from live single cells of Gambierdiscus toxicus Adachi et Fukuyo, 1979 and cells preserved using formalin/methanol fixation. This method supplements existing techniques and expands the scope of genetics studies conducted on dinoflagellates to include routine molecular analysis of single cells isolated from field samples.     

Biochemical pathways analysis of microarray results: regulation of myogenesis in pigs

Background  

Combining microarray results and biological pathway information will add insight into biological processes. Pathway information is widely available in databases through the internet.     

Major morphological effects of a regulatory gene: Pgm1-t in rainbow trout

We have investigated the morphological effects of a genetic locus, Pgm1- t, that affects the expression of a phosphoglucomutase locus (Pgm1) in liver of rainbow trout (Salmo gairdneri). We have previously shown that embryos with liver Pgm1 expression hatch earlier than those without liver Pgm1 expression. We predicted that this difference in developmental rate should cause a reduction in meristic counts in the more rapidly developing fish with liver Pgm1 expression. Eight meristic (countable) characters in nine full-sib groups segregating for the presence or absence of liver Pgm1 expression are in agreement with this prediction. In eight of the nine families, there is a significant difference in the multivariate distribution of the eight meristic counts between full sibs with and without liver Pgm1 expression. This separation in multivariate space is based on a tendency for lower meristic counts in fish with liver Pgm1 expression. The magnitude of these morphological differences is similar to that between two subspecies of cutthroat trout (Salmo clarki) that show substantial genetic divergence at structural loci encoding enzymes (Nei's D = 0.34). These data support the view that small changes in the developmental process caused by genetic differences at regulatory genes can have large effects on morphology.