The acoustic repertoire of the Southern right whale,a quantitative analysis

Some 1274 southern right whale sounds were randomly selected and each sound was described by 10 acoustic variables. Two hundred and fifty of these sounds were also ‘labelled’ by the activity, size and sexual composition o the group producing them. Principal components analysis was performed on all the sounds' variables (1274×10) and on the variables for a subset of 823 sounds referred to as calls. Results of the principal components analyses indicate that the sounds can be divided into three major classes: blow sounds, slaps, and calls; and that the repertoire of calls is a continuum with certain types more common than others. The distribution of the ‘labelled’ sounds in the principal components analyses patterns revealed general associations between whale activities and the types of sounds produced.     

Evidence of a role for catecholamines in the control of breathing in fish

Summary Our current knowledge of the control of ventilation in fish is incomplete at all levels. The respiratory rhythm originates in a medullary central pattern generator (CPG), which has yet to be clearly identified and characterized. Its activity is directly modulated by inputs from elsewhere in the CNS and from peripheral mechanoreceptors. The central location of respiratory motoneurones, innervating the various respiratory muscles, has been described in detail for some fish, particularly elasmobranchs. We are still unclear, however, about the link between the CPG and the sequential firing of the motoneurones, which result in coordinated contractions of the respiratory muscles, and about the mechanisms that result in recruitment of feeding muscles into forced ventilation. In teleosts, ventilation is matched to oxygen requirements by stimulation of gill chemoreceptors, which seem to respond to oxygen content or supply. There is little evidence of a role for these receptors in elasmobranchs.Chemoreceptor stimulation evokes a number of reflex changes in the respiratory and cardiovascular systems of fish that are rapid in onset and seem adaptive (e.g. increased ventilation and a bradycardia in response to hypoxia). Conditions that result in hypoxaemia and the consequent ventilatory changes also cause an elevation in circulating catecholamine levels. We have explored the possibility of a causal relationship between these levels and the ventilatory response. Strong evidence for this relationship arises from experiments on hypoxia and acid infusion, which trigger a ventilatory increase and a rise in circulating catecholamines. Both ventilatory responses are blocked by an injection of propranolol, indicating that adrenoreceptors are involved in the response.The ventilatory response to hypoxia, in teleosts at least, occurs very rapidly, perhaps before any marked increase in circulating catecholamines and almost certainly before any blood-borne catecholamines could reach the respiratory neurones. This argues for an immediate neuronal reflex based on chemoreceptors in the gill region responding to hypoxia. Clearly, circulating catecholamines also affect ventilation through some action in the medulla and could act in concert with a direct neuronal chemoreceptive drive during hypoxia. The studies on acid infusion during hyperoxia, where there is an acidosis but no increase in ventilation or blood catecholamines, would argue against any hydrogen ion receptor, either peripheral or central, being involved in the reflex ventilatory response to acidotic conditions in fish.The release of catecholamines into the circulation, therefore, seems to be an absolute requirement for the ventilatory response to acidosis in fish. Present evidence supports a role for -adrenergic receptors on respiratory neurones, stimulated by changes in the levels of circulating catecholamines, in the control of ventilatory responses to marked changes in oxygen availability in fish, such as those occurring in the post-exercise acidotic state.     

Histochemical analysis of rat testicular glycoconjugates. 1. Subsets of N-linked saccharides in seminiferous tubules

Summary The distribution of N-linked glycans in rat testis has been probed using a panel of lectins derived fromGalanthus nivalis (snowdrop, GNA),Canavalia ensiformis (jack bean, Con A),Lens culinaris (lentil, LCA),Pisum sativum (garden pea, PSA) andPhaseolus vulgaris, erythro- and leucoagglutinins (kidney bean, ePHA and IPHA). Several classes of N-linked glycan were identified in the spermatogenic series, and during differentiation into spermatozoa they altered in both their pattern of distribution and relative abundance. A population of tetra-antennary, non-bisected, complex glycans, detected by IPHA, was lost during the transition from spermatogonia to spermatocytes, while high-mannose structures were acquired; these were most abundant in spermatocytes, as were bi- and tri-antennary complex, non-bisected glycans, the latter becoming increasingly abundant on acrosomes and spermatozoa. Their bisected counterparts were more generally expressed throughout spermatogenic cells, although marked localization onto acrosomes and nuclear caps was again seen. Transition from spermatocytes to spermatids involved mainly changes of the acrosomal granule and nuclear cap, which were carried through to the final stages of differentiation. Sertoli cell surfaces and cytoplasmic granules showed a high level of N-glycan expression.     

Histochemical analysis of rat testicular glycoconjugates. 2. Beta-galactosyl residues in O- and N-linked glycans in seminiferous tubules.

Summary Rat testes have been examined with a panel of lectins that bind specifically to oligosaccharide sequences having terminal or subterminal -galactosyl residues in O-linked glycans, or in the outer chains of complex N-linked glycans:Arachis hypogaea (peanut, AHA),Erythrina cristagalli (coral tree, ECA),Ricinus communis (castor bean, RCA120) andAbrus precatorius (jequirity bean, APA) agglutinins. Pretreatment of sections with neuraminidase, -galactosidase and removal of alkali-labile O-linked sequences by -elimination allowed the structure of these glycans to be further explored. In spermatogonia and spermatocytes there was little evidence of glycans terminating in -galactosyl residues, although these were present at non-reducing terminals as sialylgalactosides. The acrosome contained two subsets of O-linked glycans terminating in sialylgalactosides, while the nuclear cap showed at least two subsets of N-linked sialylgalactosyl as well as O-linked glycans. Spermatozoa exhibited minor changes in the pattern of glycosylation, although the overall pattern of -galactosyl expression was similar. Binding to Sertoli cells showed the presence of some unsubstituted -galactosyl terminals on O-linked glycans but few such N-linked residues, while terminal -galactosides were scanty in tubular basement membranes.     

Two novel Streptomyces protein protease inhibitors. Purification, activity, cloning, and expression.

In contrast to the Gram-negative bacteria, Gram-positive bacteria such as Streptomyces lack a mucopolysaccharide cell wall which allows them to produce and secrete a variety of proteins directly into their environment. In an effort to understand and eventually exploit the synthesis and secretion of proteins by Streptomyces, we identified and characterized two naturally occurring abundantly produced proteins in culture supernatants of Streptomyces lividans and Streptomyces longisporus. We purified these 10-kDa proteins and obtained partial amino acid sequence information which was then used to design oligonucleotide probes in order to clone their genes. Analysis of the sequence data indicated that these proteins were related to each other and to several other previously characterized Streptomyces protein protease inhibitors. We demonstrate that both proteins are protein protease inhibitors with specificity for trypsin-like enzymes. The presumptive signal peptidase cleavage sites and subsequent aminopeptidase products of each protein are characterized. Finally, we show that the cloned genes contain all of the information necessary to direct synthesis and secretion of the proteins by Streptomyces spp. or Escherichia coli.     

Biogeographic comparisons of marine algal polyphenolics: evidence against a latitudinal trend

Summary Marine allelochemicals generally are present in greater quantity and diversity in tropical than in temperate regions. Marine algal polyphenolics have been reported as an apparent exception to this biogeographic trend, with literature values for phenolic concentrations significantly higher in temperate than in tropical brown algae. In contrast, our results, the first reported for Caribbean brown algae (orders Dictyotales and Fucales), show that many species have high phenolic levels. In addition, both our study and previous studies with north temperate and tropical species demonstrate that there is marked variation in algal phenolic levels within species from different locations. We conclude that high phenolic concentrations occur in species from both temperate and tropical regions, indicating that latitude alone is not a reasonable predictor of plant phenolic concentrations.     

Two distinct members of the ADP-ribosylation factor family of GTP-binding proteins regulate cell-free intra-Golgi transport.

We have used an intra-Golgi transport assay to identify GTP-binding proteins involved in regulation of protein traffic. Two soluble proteins of 20 kd were purified by their ability to mediate GTP gamma S-dependent inhibition of transport. These GTP-dependent Golgi binding factors, or GGBFs, exhibit a 3-fold difference in activity and are differentiated by their hydrophobicity, isoelectric points, and apparent size. Removal of 80% of GGBFs from cytosol abolishes GTP gamma S sensitivity but does not affect inhibition by aluminum fluoride. We demonstrate that GGBFs are members of the ADP-ribosylation factor (ARF) family. Recombinant ARF1 exhibits GGBF activity and myristoylation is required. The distinct biochemical properties of GGBFs indicate that members of the ARF family may have related but distinct functions in intracellular transport.