The morphology and physiological properties of nereid giant fibres

• 1.1. The three sets of giant fibres in the nerve cord of Nereis virens are connected by both electrotonic and chemically transmitting junctions.
• 2.2. The paired laterals and paramedials are connected to their partners by electronic junctions. The laterals are also electrically coupled to the median giant fibre.
• 3.3. The laterals are connected to the paramedials by an excitatory chemical synapse, while in the anterior segments the paramedials provide an inhibitory input to the median giant fibre.
• 4.4. Afferent input to the giant fibres through the segmental nerves two and four is excitatory, except that to the median fibre in the caudal segments.
• 5.5. There is no evidence of the segmental origin of the lateral giant fibres, either in the form of macrosynapses or segmental cell bodies.
• 6.6. The median giant fibre originates from two groups of cell bodies in the sub-oesophageal ganglia.

     

Neuron-glia communicatory structures in crustaceans

• 1.1. Membrane modifications and junctional structures involved in neuron-glia exchange in crustaceans are reviewed, including some new observations on the crayfish Procambarus clarkii.
• 2.2. Neuron cell bodies and associated glia interact through trans-glial channels, modified neuronal endocytosis and gap-like junctions.
• 3.3. Tubular lattices, trans-glial channels, endocytosis and capitate projections give support to axo-glial relationships.
• 4.4. Unidentified neuron-glia membrane appositions have been also found in neuropile.

     

Haematology of the australian eastern quoll,Dasyurus viverrinus

• 1.1. A variety of haematological parameters were determined in adult Dasyurus viverrinus.
• 2.2. Haemoglobin and red cell counts were high with a very low mean cell volume.
• 3.3. Basophils are absent but the eosinophils contain small numbers of basophilic granules which may indicate a dual role for this cell.
• 4.4. “Ring Form” leucocytes are present.
• 5.5. Three types of red cell picture could be identified, some animals showing large numbers of spherocytes, spicule cells, and inclusion bodies.
• 6.6. These cells resemble those found in some inherited human haemolytic anaemias but there was no evidence of haemolysis in the animals.
• 7.7. An alkali resistant haemoglobin component is present.

     

Demonstration of specific receptors for calcitonin in isolated trout gill cells

• 1.1. Salmon calcitonin binding by isolated gill cells from rainbow trout, Salmo gairdneri has been investigated.
• 2.2. The calcitonin receptor interaction is time- and temperature-dependent.
• 3.3. 50% of inhibition of the ¹²⁵I labeled calcitonin binding is observed in presence of 1.5 ng/ml unlabeled salmon calcitonin.
• 4.4. Two types of receptors are described: a high affinity-low capacity site and a low affinity-large capacity site.
• 5.5. These studies strongly support the role of calcitonin as a hormone regulating the gill function in physiological conditions.

     

Effects of membrane-perturbing drugs and noradrenalin on cAMP accumulation and red cell water content in carp (Cyprinus carpio) red cells

• 1.1. Carp red cells were treated with drugs that affect the cell membranes. The water content of the cells and the accumulation of cAMP in the cells were measured in normoxia and in hypoxia using non-stimulated and adrenergically stimulated cells.
• 2.2. WGA, DIDS + CCCP and A23187 increased the water content of nonstimulated normoxic cells.
• 3.3. In hypoxia ouabain and DIDS + CCCP increased the water content but cytochalasin B, NPM, DIDS, CCCP and A23187 + CA²⁺ abolished the hypoxia-induced swelling.
• 4.4. Any membrane perturbation induced some cAMP formation, Sophora and Anquilla lectins being most potent.
• 5.5. Also in adrenergically stimulated cells, membrane perturbation generally increased cAMP formation.
• 6.6. However, cAMP accumulation diminished in cells treated with cytochalasin B, CCCP and DIDS + CCCP.
• 7.7. The adrenergic swelling of carp red cells was reduced in normoxia by DIDS. NPM and CCCP increased the adrenergic swelling in normoxia to hypoxic level.
• 8.8. In hypoxia WGA and Anquilla lectin decreased the swelling.

     

Proteolytic system in Babesia hylomysci

• 1.1. Babesia hylomysci has an aminopeptidase and an acid endoprotease
• 2.2. The amino-peptidase has properties very similar to the aminopeptidase in Plasmodium yoelii nigeriensis and P. chabaudi.
• 3.3. The acid endoprotease is specific towards haemoglobin and practically has no action on bovine serum albumin.
• 4.4. In mouse normal red blood cells we find an acid protease having physico-chemical properties similar to the enzyme present in B. hylomysci extracts.
• 5.5. The similarity of electrophoretic velocity between acid protease in B. hylomysci and non-infected red blood cells leads us to think that the acid protease of parasitic extracts comes from the host-cell.
• 6.6. The proteolytic system of Babesia and Plasmodium are similar.

     

Osmotically-induced volume changes in isolated cells of a pond snail

• 1.1. To assess whether the stretch-activated (SA) channels in snail cells could contribute to osmoregulation, information is needed about the behaviour of the cells under anisosmotic conditions.
• 2.2. Cells of Lymnaea stagnalis were therefore examined during acute hyposmotic stress (HOS).
• 3.3. Kidney, heart and neuronal cells (monitored photographically) swelled less than expected for strictly semipermeable cells, but exhibited no regulatory volume decrease.
• 4.4. Long-term viability of the cells was not compromised following acute hyposmotic stress.
• 5.5. Quinidine, which blocks SA channels in Lymnaea, intensified stress-induced swelling most markedly in kidney cells.
• 6.6. The data can, however, be explained without invoking recruitment of SA channels.

     

Transport of cholesterol in the hemolymph of the mollusc Diplodon delodontus

• 1.1. The dietary and inter-organ cholesterol transport in the hemolymph of the bivalve mollusc Diplodon delodontus, was studied. Plasma and hemocytes were obtained after feeding labeled cholesterol to animals or injecting it into the posterior adductor muscle.
• 2.2. In both cases, cholesterol was incorporated either into plasma or hematic cells.
• 3.3. Two plasmatic fractions differing in their hydrated densities were recognized as cholesterol carriers and were isolated. They have characteristics of high density (HDL) and very high density (VHDL) lipoproteins, respectively.
• 4.4. The major lipids in the different classes of lipoproteins were free sterols in HDL and phospholipids in VHDL.
• 5.5. Neither low nor very low density lipoprotein transporting cholesterol was detected.

     

Specific biochemical and immunological properties of some water-soluble glycoproteins produced by rat gastric mucosal scrapings in vitro

• 1.1. Two major glycoprotein components were released in vitro by rat gastric mucosal cells after 4 hr incubation with radioisotopes: a high molecular weight fraction with the characteristics of a fucomucin and a low molecular weight fraction, the latter having a higher specific radioactivity than the former.
• 2.2. Pulse chase experiments indicate that several low and high molecular weight glycoproteins are synthesized simultaneously with no precursor-product relationship between them.
• 3.3. Common antigenic determinants, specific to the stomach were found on the 2 fractions, using immunofluorescence, both fractions appeared to be present in the same cells.

     

Organ specific changes in energy metabolism due to anaerobiosis in the sea mussel Mytilus edulis (L.)

• 1.1. Anaerobic energy metabolism was investigated in different organs of Mytilus edulis and the whole animal.
• 2.2. Succinate accumulates to high levels in most organs but remains low in the hemolymph.
• 3.3. After 16 hours propionate accumulation is observed in all organs. Experimental evidence is not sufficient yet to point out organs that produce more propionate than others.
• 4.4. Acetate is a minor end product.
• 5.5. Acetate and propionate are found in the hemolymph in amounts equal to those in the organs.
• 6.6. Animals incubated in oxygen-free seawater accumulate more end products than animals exposed to air, in the form of volatile fatty acids that are excreted into the incubation water.
• 7.7. Alanine and glutamine increase in the posterior adductor muscle. Aspartate decreases in the total animal, posterior adductor muscle and gills, while in the hemolymph decrease in alanine, asparagine, serine, threonine and proline are observed.

     

Effect of inorganic phosphate on synthesis of 5-phosphoribosyl-1-pyrophosphate in cultured plant cells

• 1.1. Inorganic phosphate (Pi) was absorbed rapidly by suspension-cultured cells of Catharanthus roseus which had previously been cultured in Pi-free Murashige Skoog medium.
• 2.2. The intracellular levels of ATP, ADP and 5-phosphoribosyl-l-pyrophosphate (PRPP) increased markedly during the 24 hr which followed the addition of Pi (1.25mM).
• 3.3. Availability of PRPP in vivo, estimated by the measurement of nucleotide synthesis from [8-¹⁴C]adenine, was also increased by addition of Pi.
• 4.4. Only a 20% increase in the maximum catalytic activity of PRPP synthetase was observed in extracts of cells, prepared 24 hr after addition of Pi.
• 5.5. In contrast to results for mammalian PRPP synthetase, the activity of PRPP synthetase, partially purified from Catharanthus roseus, was inhibited by concentration of Pi greater than 5mM.
• 6.6. The mechanisms involved in the increased availability of PRPP and the synthesis of adenine nucleotides in the plant cells cultured in Pi-containing medium are discussed.

     

Breast,hips, and buttocks revisited: Honest fatness for honest fitness

This paper comments on: Low, B. S., Alexander, R. D., and Noonan, K.M. Human hips, breast, and buttocks: Is fat deceptive? Ethology and Sociobiology 8: 249-247, 1987. In it I argue that:

• 1.1. Sexual selection has probably not been the most important selection pressure on
• 2.female human body shape.
• 3.2. Male humans in different cultures find different aspects of the female body attractive
• 4.and therefore are unlikely to have exerted consistent directional sexual selection on
• 5.the female body.
• 6.3. Breast size is not correlated with lactation success.
• 7.4. Visible hip width is not correlated with parturition success.
• 8.5. Women would lower their fitness if they tried to deceive men about their internal
• 9.pelvic dimensions.
• 10.6. There are many alternative hypothesis to explain the existence of fat onwomen's
• 11.breast, hips, and buttocks.

     

Seasonal variation in the energy metabolism in an estuarine crab,Chasmagnathus granulata (Dana, 1851)

• 1.1. The effects of seasonal variation on the carbohydrate and lipid metabolism of the Chasmagnathus granulata were investigated.
• 2.2. Glycemia is high in winter and summer and low in spring and fall.
• 3.3. The glycogen content in the hepatopancreas and muscle is higher in fall and winter, and decreases during spring and summer.
• 4.4. The muscle lipids are higher in summer, and decrease during fall and winter whereas hepatopancreas lipids are higher except in the fall.
• 5.5. The crabs show change in the metabolic pattern of lipids and carbohydrates during the seasons of the year.

     

Metabolic roles of carnitine expressed through the carnitine acetyltransferase system in Candida pintolopesii

• 1.1. The carnitine-responsive mutant yeast, Candida pintolopesii ATCC 26014 and the wild type strain (ATCC 22987) were used to investigate the role of carnitine and the carnitine acetyltransferase system.
• 2.2. [³H]l-Carnitine, supplied to the cells, was incorporated into acetylcamitine and [¹⁴C]pantothenate was incorporated into CoA and its derivatives.
• 3.3. Both bioautography and quantitative assays indicated that the relative amounts of CoA and acetylCoA were very different in the mutant and wild type cells.
• 4.4. The wild type yeast maintained an acetylCoA/CoA ratio of 0.33 ± 0.09 indicating that most of the CoA in the cell is in the free CoA form. Carnitine was not required to establish this ratio nor did its presence lower it further.
• 5.5. In contrast, the mutant cells contained a high acetylCoA/CoA ratio (12.8 ± 3.0).
• 6.6. In the mutant cells, carnitine lowered the ratio by decreasing the intracellular acetylCoA concentration and releasing free CoA.
• 7.7. These data indicated that wild type yeast possess an effective mechanism that is not related to the CAT system for regulating the acetylCoA/CoA ratio.
• 8.8. This mechanism appears to be lacking in the mutant. The CAT system decreased the acetylCoA/CoA ratio in the mutant cells but not to the value which is found in the wild type strain.
• 9.9. In both stains of Candida pintolopesii, in the presence of carnitine, an acetylcamitine pool can be created whose concentration exceeds that of acetylCoA.
• 10.10. The intracellular apparent equilibrium constant (K_app) for carnitine acetyltransferase for wild type Candida pintolopesii ATCC 22987 was 0.73 ± 0.12, close to the established value of 0.6, indicating that the CAT system ran close to equilibrium.
• 11.11. The K_app for the CAT system of the carnitine-responsive mutant yeast was 7.7 ± 1.7 indicating that this reaction was not at equilibrium.

     

Purification and partial characterization of an AMP deaminase from the marine invertebrate Palaemon serratus

• 1.1. AMP deaminase from Palaemon serratus tail muscle was partially purified by chromatography on cellulose phosphate.
• 2.2. Muscle homogenates expressed very low enzyme activities and the presence of ATP was necessary to detect AMP deaminase. The specific activity and substrate affinity of the purified enzyme were also very low.
• 3.3. The purified prawn muscle AMP deaminase was contaminated by contractile proteins, one of the major contaminants being actin.
• 4.4. The enzyme displayed a very high affinity for actomyosin which was only partially abolished by pyrophosphate.

     

Larval Musca domestica lipophorin biosynthesis

• 1.1. Larval Musca domestica lipophorin biosynthesis was studied in vitro.
• 2.2. The newly synthesized lipophorin has a density a little lower than the circulating lipophorin after 1 hr of incubation. After 3 hr of incubation the fat body cells transfer lipids to the lipophorin that attains the density of circulating lipophorin.
• 3.3. The lipophorin synthesized in vitro is identical to circulating lipophorin in density and in electrophoretical behavior.
• 4.4. However these two molecules must have differences since the circulating lipophorin transfers lipids to fat body cells while the synthesized in vitro does not.
• 5.5. The biosynthesis of Musca lipophorin shows differences with the Manduca sexta lipophorin biosynthesis.

     

Hematology and blood chemistry of the marsh harrier (Circus aeruginosus)

• 1.1. This study deals with the hematological and blood chemistry of 13 adult marsh harriers (Circus aeruginosus).
• 2.2. No significant differences were observed between male and female groups in any of the parameters.
• 3.3. The value of white blood cells was 14,677/mm³ heterophils and lymphocytes, these being the most abundant cellular type (81.42 and 12%, respectively).
• 4.4. Urea and uric acid are present in approximately similar proportions, though birds are said to be uricotelic.
• 5.5. The cholesterol concentration values determined in our study, are higher than those reported in most other birds.

     

The effects of ryanodine,acetylcholine and epinephrine on electrical and mechanical activity in an insect heart

• 1.1. Ryanodine, an alkaloid used as an insecticide, has been shown to depress contraction while leaving excitation unaffected in mammalian hearts, an effect presumed to result from uncoupling of the transverse tubular system (TTS) from the sarcoplasmic reticulum (SR).
• 2.2. The heart of the adult moth Hyalophora cecropia, a tissue known to have septate junctions between the TTS and SR and a Ca²⁺ -spike generating sarcolemma was used to further test this hypothesis.
• 3.3. We first report the basic characteristics of the contractile response and demonstrate a negative force-frequency effect, a diminished calcium current (I_Ca²⁺) in the presence of acetylcholine and an enhanced I_Ca²⁺ with epinephrine.
• 4.4. Ryanodine 10⁻⁸M added to this preparation slowed the inherent rhythm (interval 0.6–4 sec), depolarized the cells by 10–14 mV, reduced action-potential amplitude (from 66 to 52 mV), prolonged the plateau (from 80 to 280 msec), and decreased dV/dt from 4 to 2.8 V/sec.
• 5.5. The magnitude of peak tension was not affected, but the time to peak tension was increased from 160 to 200 msec and the relaxation time was prolonged from 200 to 480 msec.
• 6.6. The refractory period was increased, thereby preventing the heart from following increased rates of pacing by externally applied stimuli.
• 7.7. We conclude that ryanodine interferes first with the sarcolemmal Ca²⁺-delivery system and then the SR calcium-sequestration system.