The distribution and temporal dynamics of the estuarine macroalgal community of San Francisco Bay

Long-term sampling of intertidal macroalgae along permanently marked transects within San Francisco Bay has shown a marked decline in overall species number along the estuarine gradient from the ocean to the river, presumably as a result of decreasing salinity and a progressive lack of hard substrata in the upstream direction. Green algae penetrated further landward than either brown or red species. Seasonally, macroalgal species diversity is lowest during the winter-spring months when salinity, temperature, and irradiance are at yearly minima. Macroalgal abundance as measured by percent cover was maximum during the late spring near the mouth of the estuary and during late summer towards the head. The seasonal increase in algal abundance is related to increasing salinity, temperature, and light availability to the bottom. The summer increase in irradiance is due to the longer photoperiod, increased frequency of day-time low tides, and reduced levels of suspended sediments. The aperiodic occurrence of algal blooms in San Pablo Bay may be caused by a combination of physical factors which are ultimately associated with the river inflow. A hypothesis based on interannual differences in river inflow and the contribution of phytoplankton to nutrient cycles in the benthos is presented to explain the occurrence of nuisance algal blooms.     

Concentration of Free Amino Acids in Primary Cultures of Neurones and Astrocytes

The cellular distribution of free amino acids was estimated in primary cultures (14 days in vitro) composed principally of cerebellar interneurones or cerebellar and forebrain astrocytes. In cultured neural cells, the overall concentration of amino acids resembled that found in brain at the corresponding age in vivo. In the two neural cell types, there were marked differences in the distribution of amino acids, in particular, those associated with the metabolic compartmentation of glutamate. In neuronal cell cultures, the concentrations of glutamate, aspartate, and gamma-aminobutyric acid were, respectively, about three, four, and seven times greater than in astrocytes. By contrast, the amount of glutamine was approximately 65% greater in astroglial cell cultures than in interneurone cultures. An unexpected finding was a very high concentration of glycine in astrocytes derived from 8-day-old cerebellum, but the concentrations of both serine and glycine were greater in nerve cell cultures than in forebrain astrocytes. The essential amino acids threonine, valine, isoleucine, leucine, tyrosine, phenylalanine, histidine, lysine, and arginine were all present in the growth medium, and small cellular changes in the contents of some of these amino acids may relate to differences in their influx and efflux during culturing and washing procedures. The present results, together with our previous findings, provide further support for the model assigning the "small" compartment of glutamate to glial cells and the "large" compartment to neurones, and also underline the metabolic interaction between these two cell types in the brain.     

Improved Method for Isolating Synaptosomes from 11 Regions of One Rat Brain: Electron Microscopic and Biochemical Characterization and Use in the Study of Drug Effects on Nerve Terminal γ-Aminobutyric Acid in Vivo

A procedure is described for the rapid preparation of nerve ending particles (synaptosomes) from 11 regions of one rat brain. The synaptosomal fractions have been characterized by electron microscopy and determination of four marker enzymes, i.e., glutamate decarboxylase (GAD), acetylcholinesterase, succinate dehydrogenase, and glycerol 3-phosphate dehydrogenase. Comparison with a much lengthier standard (Ficoll-sucrose) preparation showed that the synaptosomal yield of the new procedure was substantially better as judged by both morphological evaluation and protein recovery. The improved synaptosome preparation was used for determination of regional gamma-aminobutyric acid (GABA) levels in synaptosomal fractions. The postmortem increase in GABA level during removal and dissection of brain tissue and homogenization and fractionation procedures could be minimized by rapid processing of the tissue at low temperatures and inclusion of the GAD inhibitor 3-mercaptopropionic acid (3-MP; 1 mM) in the homogenizing medium. The addition of GABA (0.2 mM) to the homogenizing medium did not alter the GABA levels in the synaptosomes, indicating that no significant redistribution of GABA occurred during subcellular fractionation in sodium-free media. Synaptosomal GABA levels determined in the 11 rat brain areas showed the same regional distribution as the GABA-synthesizing enzyme GAD. On the basis of these findings, it was suggested that the synaptosome preparation could be used to evaluate the in vivo effects of drugs on nerve terminal GABA. Treatment of rats with a convulsant dose of 3-MP (50 mg/kg i.p.) 3 min before decapitation significantly lowered synaptosomal GABA levels in olfactory bulb, hippocampus, thalamus, tectum, and cerebellum. The 3-MP-induced seizures and reduction of GABA levels could be prevented by administration of valproic acid (200 mg/kg i.p.) 15 min before the 3-MP injection. The data indicate that the improved synaptosome preparation offers a convenient method of preparing highly purified synaptosomes from a large number of small tissue samples and can provide useful information on the in vivo effects of drugs on regional GABA levels in nerve terminals.     

Regional Distribution of Calmodulin Activity in Rat Brain

Calmodulin activity in 68 discrete areas of rat brain, obtained by micropunch technique, was assessed by its capacity to activate a calmodulin-sensitive form of phosphodiesterase. In general, the activity of calmodulin was higher in the telencephalon, limbic system, and hypothalamus than in the mesencephalon, pons, cerebellum, and medulla. However, there were substantial differences in calmodulin activity in discrete nuclei of each region. The regional distribution of calmodulin activity in rat brain does not appear to correlate with that of any of the known putative neurotransmitters or peptides.     

Cholinergic- and Adrenergic-Stimulated Inositide Hydrolysis in Brain: Interaction, Regional Distribution, and Coupling Mechanisms

Carbachol and norepinephrine were used as agonists to compare and contrast cholinergic and adrenergic stimulation of inositide breakdown in rat brain slices. Carbachol acts through a muscarinic (possibly M1) receptor and norepinephrine acts through an alpha 1 adrenoceptor. Studies in cerebral cortical slices indicated that both agonists stimulated the production of inositol-1-phosphate and glycerophosphoinositol. Although the initial rates for the stimulation of inositol phosphate release were similar for the two ligands, the response to norepinephrine continued for 60 min and was larger compared with carbachol which plateaued at 30 min. The presence of carbachol did not affect the ED50 for norepinephrine. Concentrations of carbachol near the ED50 in combination with norepinephrine resulted in an additive response whereas maximal concentrations of carbachol and norepinephrine resulted in a less than additive response in the cortex. This negative interaction was also seen in the hippocampus and hypothalamus but not in the striatum, brainstem, spinal cord, olfactory bulb, or cerebellum. Norepinephrine had a larger response than carbachol in the hippocampus, striatum, and spinal cord, but the reverse was true in the olfactory bulb. Manganese (1 mM) stimulated the incorporation of [3H]inositol into phosphatidylinositol (PtdIns) four- to fivefold but not into polyphosphoinositides. The stimulation by manganese of PtdIns labelling increased the nonstimulated release of inositol phosphates but did not affect the stimulated release of inositol phosphates by carbachol or norepinephrine.(ABSTRACT TRUNCATED AT 250 WORDS)     

Microwave radiation absorption in the rat: frequency-dependent SAR distribution in body and tail

Experiments were conducted using twin-well calorimetry to determine the averaged whole-body specific absorption rate (SAR) for rat carcasses exposed to 360, 700, 915, and 2,450 MHz CW radiation in an anechoic chamber. All exposures were done with the long axis of the rat in an E-polarization. Additional experiments were conducted using a fiber optical temperature probe to determine local SAR in the brain, esophagus, colon, rectum, and tail during microwave exposure. The whole-body averaged SAR for the radiation frequencies examined follows a nonmonotonic function with 700 MHz as the resonant frequency. This result agrees with previous analytical estimates. Local SARs within the body and tail are nonuniform with significant frequency-specific hotspots in the colon, rectum, and tail.     

Epitope distribution and immunochemical characterization of nucleolar phosphoprotein C23 using ten monoclonal antibodies

Summary Extractable nucleolar proteins from HeLa cells were used as a source of antigen to immunize mice for monoclonal antibody (MAb) production. Ten of the resulting MAbs shown to identify nucleolar phosphoprotein (110 kD/pI 5.5) were purified and used in immunochemical studies to further characterize protein C23. All ten MAbs showed nucleolar localization by indirect immunofluorescence; one antibody (FR2) also showed some nucleoplasmic localization that was attributed to a shared epitope between protein C23 and a 72 kD nuclear/nucleolar antigen. Reciprocal antibody cross blocking studies indicated that the ten MAbs identified nine distinct epitopes on protein C23. Interestingly, seven of the nine epitopes were shown by immunofluorescence and competitive ELISA studies to be species related. Immunostained patterns of exponentially growing HeLa cells suggest that protein C23 exists in vivo solely as a 110 kD peptide. However, protein C23 was subject to rapid degradation into a number of proteolytic fragments upon extraction or storage of isolated nucleoli. The failure to find protein C23 related peptides with molecular sizes less than 110 kD in exponentially growing cells and the lack of cytoplasmic localization of any of the ten MAbs suggests that protein C23 is not a prepro-protein processed in vivo to form ribosomal proteins as previously suggested (1).     

Subcellular localization and glycoprotein nature of the invertase from the fission yeast Schizosaccharomyces pombe

The subcellular localization of the enzyme invertase in Schizosaccharomyces pombe cells, both repressed and derepressed for synthesis of the enzyme, was studied. Most of the invertase was found to be located outside the plasma membrane and only a small percentage was found to be associated to membranes. A substantial portion of the external enzyme remained firmly bound to cell-wall material.All of the invertase recovered in soluble form from cellular extracts reacted with concanavalin A and with the lectin from Bandeiraea simplicifolia seeds, indicating the presence in the enzyme of a carbohydrate moiety which probably contains terminal mannosyl (or structurally related) and galactosyl residues.The possibility of the presence of two different forms of invertase in S. pombe was considered. An intracellular, soluble form of invertase, devoid of carbohydrate, similar to the small invertase of the budding yeast Saccharomyces cerevisiae, was not found in S. pombe. However, the Michaelis constant for sucrose of the enzyme present in repressed cells was smaller than that of the invertase synthesized under derepressing conditions, although this difference could also be the result of a different pattern of glycosylation of the invertase synthesized under different growth conditions.     

A biological sampling problem illustrated by the population structure and growth patterns of Sardinella aurita at Tripoli,Libya

Synopsis Sardinella aurita were sampled from catches of the lampara fishery at Tripoli, Libya during October 1979 through to September 1980. Landings consisted mainly of adult fish with large (mode 21–26 cm total length), relatively fast growing 3–5-group individuals in winter and spring and smaller (mode 14–20 cm total length), slow growing 2- and 3-group fish in summer. Gonad growth commenced in April, when the fish were feeding on zooplankton, and continued at the expense of mesenteric fat until July. It is suggested that the older and bigger fish spawn first, probably after having moved westwards, and that this results in spatial and temporal differences in length at age within the population. There was no consistent difference in growth rate between the sexes, but because first maturity in males tends to occur earlier than in females, there were length distribution differences between the sexes in the youngest (2+) age group as sampled.