Kinetics of force redevelopment in isolated intact frog fibers in solutions of varied osmolarity.

Isolated intact frog muscle fibers, while shortening with the intrinsic maximal speed, were stretched back to the original length to measure the kinetics of force redevelopment. These kinetics give information on the attachment rate constant in the cross-bridge cycle in vivo, and a value of approximately 25.6 s-1 (0 degree C) is found in the present study. We find that these kinetics were slightly less sensitive to temperature than was the unloaded shortening speed. The effect of hyperosmolarity on force redevelopment was also measured in solutions with added sucrose or KCl. The rate constant was nearly halved with 120 mM sucrose, but there was practically no effect with isosmotic (60 mM) KCl. These results indicate that the rate constant of force redevelopment is insensitive to raised intracellular ionic strength. In sucrose, the fiber width was also compressed, and the attenuation of the rate constant of force redevelopment in this case is consequently attributed to the decrease in interfilament space. The order of magnitude of the rate constant found in this study suggests that tension transduction by a cross-bridge, during each turnover cycle, requires a series of elementary steps following the attachment.     

Precise location of breakpoints in a frequent reciprocal translocation between chromosomes 11 and 22

One of the most frequent chromosomal translocations in human beings is 11q/22q, which results in the "partial trisomy of 22q syndrome." However, the breakpoint on the long arms of chromosomes 11 and 22 is still a matter of controversy. In the present study, we have used chromosomes from lymphocytes of a neonate who happened to have this classical abnormality, and by R-banding prometaphase chromosomes with acridine orange it has been possible to establish that the translocation between chromosomes 11 and 22 resulted from 3:1 meiotic maternal nondisjunction. A detailed analysis of the chromosome regions involved in this translocation revealed that the breakpoints on chromosomes 11 and 22 were at 11q23.3 and 22q11.1, respectively.     

Autonomy of the wingless mutation in Drosophila melanogaster

Summary T(Y;2) translocations were used to cytologically localise the wingless locus of Drosophila melanogaster. We found that an existing T(Y;2), which is an insertion of a segment of 2L into the Y chromosome, has wg ⁺ within this insert. This Y chromosome was used to generate an attached XY chromosome containing wg ⁺. The mutation claret-nondisjunctional (ca ^nd) was used to induce the loss of this XY chromosome and thus generate gynandromorphs with wg ¹/wg ¹ male tissue and wg ⁺/wg ¹/wg ¹ female tissue. Analysis of these gynanders demonstrated that a genotypically wingless mutant hemithorax is usually also phenotypically mutant in these half body mosaics; thus wg ¹ is discautonomous. This observation is of interest as it is known that wg is not cell autonomous.     

Comparison of AMP and NADH binding to glycogen phosphorylase b

The binding sites for the allosteric activator, AMP, to glycogen phosphorylase b are described in detail utilizing the more precise knowledge of the native structure obtained from crystallographic restrained least-squares refinement than has hitherto been available. Localized conformational changes are seen at the allosteric effector site that include shifts of between 1 and 2 A for residues Tyr75 and Arg309 and very small shifts for the region of residues 42 to 44 from the symmetry-related subunit. Kinetic studies demonstrate that NADH inhibits the AMP activation of glycogen phosphorylase b. Crystallographic binding studies at 3.5 A resolution show that NADH binds to the same sites on the enzyme as AMP, i.e. the allosteric effector site N, which is close to the subunit-subunit interface, and the nucleoside inhibitor site I, which is some 12 A from the catalytic site. The conformations of NADH at the two sites are different but both conformations are "folded" so that the nicotinamide ring is close (approx. 6 A) to the adenine ring. These conformations are compared with those suggested from solution studies and with the extended conformations observed in the single crystal structure of NAD+ and for NAD bound to dehydrogenases. Possible mechanisms for NADH inhibition of phosphorylase activation are discussed.     

Immunohistochemical localization of bursin in epithelial cells of the avian bursa of Fabricius

Antibodies to the avian B-cell-differentiating hormone bursin (lysyl-histidyl-glycine amide) were raised in mice and rabbits by immunizing with bursin conjugates in Freund's adjuvant. Immunohistochemical staining with these bursin-specific antibodies was restricted to follicular and dendritic reticular epithelial cells of the bursa of Fabricius, and was not found in control avian tissues.     

Endoglucanase from the mixed culture of Trichoderma reesei and Aspergillus wentii

The level of α-mannanase in mixed fungal culture of Trichoderma reesei, D1-6, and Aspergillus wentii, Pt 2804, affects the extracellular activities of cellulase. The endoglucanase component of the cellulase system is a glycoprotein having mannose and other sugars and sugaramines in its glycan moiety. Its activity is inhibited by α-mannanase. The inactivation of endoglucanase by α-mannanase can be prevented by galactose.     

Viral replication is required for induction of ocular immunopathology by herpes simplex virus.

Corneal infection of BALB/c mice with herpes simplex virus type 1 results in a chronic inflammatory response in the stroma termed herpetic stromal keratitis (HSK). This disease is considered to be immunopathological and mediated primarily by CD4+ T cells of the type 1 cytokine profile. However, the nature of the antigens, virus or host derived, which drive the inflammatory response remains in doubt. In this study, the relevance of infection with replicating virus for the subsequent development of HSK was evaluated with immunocompetent mice as well as with SCID mice reconstituted with herpes simplex virus-immune CD4+ T cells. In the corneas of immunocompetent mice, infectious virus, viral antigen, and mRNA expression were detectable for only a brief period of time (< or = 7 days postinfection), and all were undetectable by the time clinical lesions were evident (10 to 15 days). Viral replication, however, was necessary for the development of HSK in both models, since infection with UV-inactivated virus or with mutant viruses which were incapable of multiple rounds of replication in vivo failed to induce HSK. The inactivated and mutant viral preparations did, however, stimulate T-cell immune responses in immunocompetent mice. The results are discussed in terms of possible involvement of host antigens exposed in response to transient progeny virion replication in the immune-privileged cornea.     

Clustering in non-stationary environments using a clan-based evolutionary approach

 Clustering techniques are used to discover structure in data by optimizing a defined criterion function. Most of these methods assume that the data are stationary, and these techniques are based on gradient descent which converge to a locally optimal clustering. There are many potential applications that require clustering to be performed in non-stationary temporal environments. In this paper, we investigate the applicability of a clan-based evolutionary optimization method for clustering data in non-stationary environments. Due to the stochastic nature of the technique, the problem of becoming entrapped in local optima is avoided, and the method can converge to (nearly) optimal clusters. Different cases are considered in the experiments, and the results demonstrate the efficacy of the evolutionary approach for clustering time-varying data. Received: 7 September 1994/Accepted in revised form: 28 March 1995     

Effect of neonatal monosodium glutamate on the activities of glutamate dehydrogenase and aminotransferases in the circumventricular organs of rat brain

Summary Glutamate (Glu) the major amino acid in mammalian brain and most dietary proteins possesses neurotransmitter as well as neurotoxic properties. We administered monosodium glutamate (MSG) 4 mg/g bwt, sc on postnatal day (PND) 1 through 10 to rats on alternate days or daily and sacrificed them on PND 45 or PND 90 respectively. The activities of glutamate dehydrogenase and aminotransferases were evaluated in the circumventricular organs of brain. Results show that neonatal MSG produces alterations in glutamate metabolism in blood-brain-barrier deficient regions.     

Neuroanatomy of the central nervous system of the wandering spider,Cupiennius salei (Arachnida,Araneida)

Summary In Cupiennius salei (Ctenidae), as in other spiders, the central nervous system is divided into the supraoesophageal ganglion or brain and the suboesophageal ganglia (Fig. 1). The two masses are interconnected by oesophageal connectives. The brain gives off four pairs of optic and one pair of cheliceral nerves. From the suboesophageal ganglia arise a pair of pedipalpal, four pairs of leg, and several pairs of opisthosomal nerves (Fig. 2). 1. Cell types. In the brain a total of 50900 cells were counted, in the suboesophageal ganglia 49000. They are all monopolar cells, found in the ganglion periphery and may be classified into four types: (a) Small globuli cells (nuclear diameter 6–7 m) forming a pair of compact masses in the protocerebrum (Fig. 10b); (b) Small and numerous cells (cell diameter 12–20 m) with processes forming the bulk of the neuropil in the brain and suboesophageal ganglia; (c) Neurosecretory cells (cell diameter ca. 45 m) in the brain and suboesophageal ganglia; (d) Large motor and interneurons (cell daimeter 40–112 m), mostly in the suboesophageal ganglia (Figs. 10a and c). 2. Suboesophageal mass. The cell bodies form a sheet of one to several cell layers on the ventral side of each ganglion and are arranged in groups. Three such groups were identified as motor neurons, four as interneurons. At the dorsal, dorso-lateral, and mid-central parts of the ganglion there are no cell somata. The fibre bundles arising from them form identifiable transverse commissural pathways (Fig. 9b). They form the fibrous mass in the central part of the suboesophageal mass.Neuropil is well-formed in association with the sensory terminations of all major nerves (Fig. 9a). As these proceed centrally they break up into five major sensory tracts forming five layers one above the other. There are six pairs of additional major longitudinal tracts arranged at different levels dorsoventrally (Fig. 8). They ascend into the brain through the oesophageal connectives and terminate mostly in the mushroom bodies and partly in the central body. 3. Protocerebrum. Fine processes of the globuli cells form the most important neuropil mass in the fibrous core, called the mushroom bodies. These consist of well developed glomeruli, hafts, and bridge which are interconnected with the optic masses of the lateral eyes and most fibre tracts from the brain and suboesophageal mass (Fig. 7). The median eye nerves form a small optic lamella and optic ganglia, connected to the central body through an optic tract. Each posterior median and posterior lateral eye nerve ends in large optic lamellae (Fig. 13a). These are connected through chiasmata to a large optic mass where fibres from globuli cells form conspicuous glomeruli. There are 10–12 large fibres (diameter 9 m) of unknown origin on each side, terminating in the optic lambella of the posterior lateral eye.The central body, another neuropil mass (Fig. 13b) in the protocerebrum, is well developed in Cupiennius and located transversely in its postero-dorsal region (Fig. 10d). It consists of two layers and is interconnected with optic masses of the median and lateral eyes through optic tracts. Fibre tracts from the brain and suboesophageal mass join the central body.