Biochemical dynamics of spermatogenesis and oogenesis in Eledone cirrhosa and Eledone moschata (Cephalopoda: Octopoda)

The effect of spermatogenesis and oogenesis on protein, lipid, glycogen, cholesterol and energy contents, total amino acid and fatty acid profiles of Eledone cirrhosa and Eledone moschata tissues (gonad, digestive gland and muscle) was investigated. A significant (p<0.05) increase in the amino acids and protein content of the gonad throughout sexual maturation (namely in oogenesis) was observed, but the allocation of these nitrogen compounds from the digestive gland and muscle was not evident. The major essential amino acids (EAA) in the three tissues were leucine, lysine and arginine. The major nonessential amino acids (NEAA) were glutamic acid, aspartic acid and alanine. A significant increase in lipid and fatty acid contents of gonad and digestive gland was observed. There was also little evidence of accumulated lipid storage reserves being used for egg production. It seems that for egg production Eledone species use energy directly from food, rather than from stored products. Most of saturated fatty acid (SFA) content of the three tissues was presented as 16:0 and 18:0, monounsaturated fatty acid (MUFA) content as 18:1 and 20:1 and polyunsaturated fatty acid (PUFA) content as 20:4n-6, 20:5n-3 and 22:6n-3. Cholesterol and glycogen contents significantly increased in gonad and digestive gland throughout maturation while the muscle revealed no obvious pattern. If Eledone's component sterols are of a dietary origin, a considerable variation in the cholesterol content between species might be expected on the basis of the sterol composition of their prey. Although spermatogenesis and oogenesis had a significant effect (p<0.05) in gonad and digestive gland energy content, the biochemical composition of digestive gland and muscle may not be primarily influenced by sexual maturation, but rather by other biotic factors such as feeding activity, food availability, spawning and brooding.     

Hole-drilling in crustaceans by Eledone cirrhosa (Mollusca: Cephalopoda)

Eledone drills holes in the carapace of crustaceans with the tooth-covered salivary complex in conjunction with salivary secretions.     

Glucose metabolism in the rat small intestine: the effect of glucose analogues on hexokinase activity (Short Communication)

The effect of intubation of starved rats with solutions of glucose, 3-O-methylglucose, mannose, 2-deoxyglucose and sorbitol on the subcellular location of hexokinase in the mucosa of the small intestine was studied. Glucose, 3-O-methylglucose and mannose caused the soluble hexokinase activity to rise to a value similar to that found in fed animals, whereas sorbitol and 2-deoxyglucose caused smaller increases.     

Analysis of the functional heterogeneity of the small intestine by glucose transport parameters]

Functional heterogeneity of the small intestine is discussed with consideration to the heterogeneity of the enterocyte populations by the accumulating and autoregulating properties and the systems of the initial and final absorption stages (particularly by their time organization parameters).     

Absorption of tetraethylammonium (TEA+) by perfused lobster intestine

The organic cation, tetraethylammonium (TEA(+)), is actively secreted by mammalian nephrons and crustacean urinary bladders by similar processes in both animal groups. These mechanisms consist of a basolateral Organic Cation Transporter (OCT family) that employs the transmembrane electrical potential as a driving force for organic cation uptake from the blood and a brush border secondary active transport process that exchanges luminal protons for TEA(+). The present study examined the nature of (14)C-TEA(+) transport across the perfused intestinal epithelium of the American lobster, Homarus americanus, to ascertain whether the gut complemented the kidneys in the clearance of these organic metabolites from the blood. Unidirectional mucosa to serosa (M to S) (14)C-TEA(+) fluxes in anterior and posterior intestine were hyperbolic functions of luminal [TEA(+)] and significantly (P<0.01) exceeded the respective serosa to mucosa (S to M) fluxes. Luminal quinine (1 mM) significantly (P<0.05) inhibited M to S flux of the organic cation, while serosal addition of the drug had no effect on S to M transfer of TEA(+). Reducing serosal pH from 7.20 to 6.02 significantly (P<0.01) stimulated M to S transfer of 0.1 mM (14)C-TEA(+), but significantly (P<0.05) lowered S to M transfer of the metabolite. Addition of 2.0 mM unlabelled serosal TEA(+) trans-stimulated the M to S flux of 0.1 mM (14)C-TEA and doubled the transfer rate of the organic cation from lumen to blood compared to its transport in the absence of TEA(+) in the bath. Results suggest that this organic cation is absorbed across lobster intestine by the combination of a brush border OCT-1-like transporter coupled with a basolateral H(+)/TEA(+) exchanger. A working model is presented for intestinal organic cation absorption in crustaceans and compared to the secretory transport model for this class of metabolites previously reported for crustacean and mammalian kidneys.     

Hole boring of crustacean prey by the octopus Eledone cirrhosa (Mollusca, Cephalopoda)

Eledone cirrhosa has been found to make a borehole in the carapace of a high proportion of its crustacean prey. This is the first account of drilling in crustaceans by octopus. The frequency of incidence of the boring behaviour varied between prey species from 17 to 93% of those killed. The incidence of boreholes was higher in crabs killed by small octopuses. Using crabs mainly of the genera Cancer, Carcinus, Corystes and Macropipus , the distribution and orientation of the boreholes was recorded. The boreholes occurred in any part of the carapace but the great majority were found close to the mid-line and in the posterior half. The long axis of the oval penetration was usually aligned with the anteroposterior axis of the crab. The Mediterranean species Eledone moschata was also found to bore crabs, and newly hatched juveniles of this species are capable of boring as early as their second killing of a live crab. No evidence was found that Octopus vulgaris normally bores the carapace of crabs.     

Comparative study of the insulin-secreting effects of L (+) and of D (-) sodium lactate]

Both sodium 6(+) and D(-) lactate stimulate insulin secretion from the isolated perfused rat pancreas; however the insulin secretory effect of the L(+) form is much superior to that of the D(-) form. Glucagon secretion is not modified by the two isomers.     

Absorption of antisense oligonucleotides in rat intestine: effect of chemistry and length

An in situ single-pass perfusion model was used to assess the effect of chemical modification and length on permeability and absorption of various oligonucleotides in rat intestine. Phosphorothioate oligodeoxynucleotides (PS-ODN) were compared with oligoribonucleotides with 2'-methoxyethyl (MOE) or 2'-O-methyl (OMe) modifications. A 25-mer PS-OMe-modified oligonucleotide showed relatively poor permeability in this model, as did unmodified 20-mer PS-ODN (permeability coefficient [P(eff)] = 2-8 X 10(-6)cm/sec). Modifying some or all of the oligonucleotides with 2'-MOE groups on deoxyribose and 5'-methylation of the cytosines substantially increased intestinal permeability of oligonucleotides. Both partially and fully modified PS-MOE oligonucleotides showed a (2-4)-fold increase in permeability as compared with unmodified PS-ODN. The presence of a phosphodiester backbone in MOE-modified compounds led to further increases in intestinal permeability. PS-MOE composed of 6, 8, 10, 12, 14, 16, 18, 20, and 22 nucleotides were also examined. It was found that the permeability of these oligonucleotides increased linearly with decreasing length.     

Absorption of radioactive lead (210Pb) by different parts of the intestine in young and adult rats.

Absorption of radioactive lead (210Pb) was studied in an intestinal preparation from adult and young rats. Absorption was higher in the jejunal parts than in the duodenum or colon. Moreover, absorption in young rats was greater than in adults. No difference in absorption was found after loading with large amounts of lead. Maintaining the animals on a low calcium diet decreased rather than increased lead absorption.