Localization of a single sperm membrane autoantigen (RSA-1) on spermatogenic cells and spermatozoa

The rabbit sperm membrane autoantigen RSA-1 is a sialoglycoprotein of 13,000 daltons which first appears on the surface of pachytene spermatocytes. Using specific antiserum to RSA-1 the antigen has been localized by immunofluorescence and immunoperoxidase staining. On testicular cells labeled at 37°C, RSA-1 is seen in patches on the surfaces of pachytene spermatocytes, round spermatids, and over the acrosomal area of later spermatids and spermatozoa. Over the postacrosomal and middle-piece regions of late spermatids and spermatozoa the labeling appears uniform. The uniformity can be seen to stop abruptly at the equatorial segment-postacrosomal border. Labeling cells after fixation gives a uniform distribution of label over the surface where patches were seen at 37°C. The polypeptides recognized by the antiserum used for labeling were identified by immunoadsorbent chromatography and subsequent SDS-PAGE. In testicular cells anti-RSA-1 recognizes the 13,000-dalton form and another component which migrates with the dye front. In ejaculated spermatozoa anti-RSA-1 recognizes a distinct ejaculate complex of higher-molecular-weight proteins containing an 84,000-dalton major band and five minor components.     

Isolation and properties of a capillary injury-related protease from lung lymph

Lung microvascular injury induced in sheep by intravenous infusion of Escherichia coli endotoxin, oleic acid, or air emboli caused the appearance in lung lymph of high levels of a protease with trypsin-like activity. The enzyme was isolated as an apparently homogeneous protein from pooled samples of active lung lymph, after an almost 9000-fold purification by affinity chromatography on columns of Reactive Blue 2-agarose, aprotinin-agarose, and p-aminobenzamidine-agarose, and chromatography on a column of Sephadex G-100. A molecular weight of about 70,000 to 75,000 was determined from mobility in polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The pH optimum was between 7.3 and 7.6. The isolated enzyme was quite labile, rapidly losing activity at both 37 and 25 degrees C. Addition of albumin to enzyme solutions protected against inactivation. Inhibition by diisopropylfluorophosphate and phenylmethanesulfonyl fluoride indicated that the enzyme belongs to the class of serine proteases. The enzyme cleaved peptide bonds on the carboxyl side of arginine residues and showed a relatively high affinity toward peptides containing several basic amino acid residues. Bonds involving the carboxyl group of lysine were cleaved at a much slower rate. The enzyme showed no plasminogen activator activity and its substrate specificity was quite different from that of several proteases of the clotting cascade. Its appearance in lymph was not influenced by lymph clotting and the isolated enzyme was not capable of correcting the clotting defect of plasmas deficient in factors XII, XI, IX, VII, and X.     

A hydrodynamical model of bordered pits in conifer tracheids

Bordered pits are small structures in the cell walls of tracheid xylem cells in plants. Coniferous bordered pits are typified by a closing membrane possessing a torus and margo structure. This paper presents a hydrodynamical model which supports the conjecture that coniferous bordered pits act like valves to fluid flowing in the xylem pathway.By means of an approximate solution and a corresponding stability analysis, the model is shown to permit only flows with flow rates smaller than a certain critical flow rate $\text{Q}{}^1$. Flow rates larger than $\text{Q}{}^1$ are shown to be associated with an unstable equilibrium configuration. As a result of this instability, the pit “snaps” shut and stops the flow.     

Cryothalamectomy for Parkinson's Disease

In a review of 61 patients with Parkinson''s disease who were treated by cryothalamectomy, the technique of freezing a surgical target as compared with destroying it by alcohol or thermal heat was found effective and to a degree safer than other techniques. One patient died of unexpected cerebral hemorrhage. Of patients considered excellent candidates for the operation, 80 per cent had excellent and good results, while those considered good candidates showed 85 per cent excellent and good results. The results are more dependent on the selection of the patient as a candidate and the diffuseness of the pathophysiological circuits involved than on the technical factors of the cryogenic procedure.     

Institutional Management of Core Facilities during Challenging Financial Times

The economic downturn is likely to have lasting effects on institutions of higher education, prioritizing proactive institutional leadership and planning. Although by design, core research facilities are more efficient and effective than supporting individual pieces of research equipment, cores can have significant underlying financial requirements and challenges. This paper explores several possible institutional approaches to managing core facilities during challenging financial times.     

A mathematical model of the effects of Co2 on stomatal dynamics

We extend a previous model of stomatal dynamics (Delwiche & Cooke 1977) which accounted for hydraulic feedback effects but which omitted CO₂ feedback effects. The present work includes both feedback loops in a model featuring the CO₂ chemistry of the guard cell. The model consists of three first order non-linear differential equations which are treated by numerical integration.     

Interaction of odour and flow perception and the effects of parathion in the locomotor orientation of the goldfish Carassius auratus L.

The effects were studied of a 24 h exposure to a subacute concentration of parathion (0.33 p.p.m., which is approximately equivalent to 0.5 of the 48-h LC₅₀) on the locomotor orientation of mature goldfish Carassius auratus L., 26–30 cm long, in response to a food odour and a water flow differential, singly and in combination, in a free choice situation. Prior to exposure, food odour alone was significantly attractive but the combination 'food odour with increased water flow', as compared with the control situation, was avoided. Factorial analysis demonstrated interaction between odour and increased flow. After exposure to parathion the food odour ceased to be attractive and was significantly avoided. This avoidance was not present in the 'food odour-increased flow' combination. The parathion exposure did not affect the response to the flow conditions per se but reversed the interaction between food odour and increased flow. In addition, the exposure to the pesticide itself, in a second order interaction, interacted with 'food odour-flow' response. Hence, the short term exposure to the subacute organophosphate concentration affected not only the perception of food odour and flow individually, but also the interaction between these common environmental stimuli.     

A Note on Testing Hypotheses about Trimmed Means

A well known result is that skewness can cause problems when testing hypotheses about measures of location, particulary when a one-sided test is of interest. Wilcox (1994) reports both theoretical and simulation results showing that when testing hypotheses about trimmed means, control over Type I error probabilities can be substantially better than methods for means. However, at least in some situations, control over the probability of a Type I error might still be judged to be inadequate. One way of adressing this concern is to combine trimmed means with the bootsrap method advocated by Westfall and Yuong (1993). This note reports simulation results indicating that there are situations where substantial improvements over Type I error probabilities are indeed obtained.