The biology of pike, Esox lucius L., in a southern eutrophic lake

The biology of pike, Esox lucius L., in a southern productive lowland lake is described. Scales and opercular bones were difficult to read and interpret, and growth estimated had perforce to be based on scale readings. Growth of Slapton pike is average and intermediate between recorded extremes. Both male and female pike reached maximum condition in February, just prior to spawning. The population of pike of over 450 mm fork length in the lake was estimated at 870·6 ± 389·3 in 1975, and 950·4 ± 143.3 in 1976/77. This leads to the conclusion that the pike population has one of the highest biomasses per surface area of water ever recorded. Number of pike per unit area of surface was also high, despite the fact that a significant proportion of the population (fish under 450 mm) could not be adequately sampled. Mean instantaneous mortality rate was 0·53, and mean instantaneous survival rate was 0·59. The roach provided the main item of diet of the pike, with perch taken less readily. Immature pike ate a significant proportion of invertebrates, but roach was again a common feature of the diet of even small fish. Two spawning migrations were identified; at other times of the year, pike were non territorial. The majority of pike spawned in March. Fecundity of a sample of females was assessed. Overall sex ratio was 1:1.     

In vivo phosphorylation of isocitrate lyase inEscherichia coli andAcinetobacter calcoaceticus

Isocitrate lyase inEscherichia coli and inAcinetobacter calcoaceticus is phosphorylated when the cells are grown with acetate as the sole carbon source in low-phosphate mineral salts medium containing³²P inorganic phosphate. The level of³²P incorporation into the enzyme in both microorganisms appears to be constant throughout the entire growth cycle. Further, theresults of immunoblots and rocket immunoelectrophoresis suggest that the amount of isocitrate lyase protein, although at different levels in each microorganism, also remains constant throughout the growth cycle.     

A new species ofTrichogramma [T. Cordubensis n. sp.] [Hym.: Trichogrammatidae], parasitoid ofHeliothis eggs in cotton crops in the sw of spain

Trichogramma cordubensis n. sp. is a parasite ofHeliothis armigera Hb. eggs in cotton crops in western Andalusia. Reproduced onEphestia kuehniella Zeller eggs, it is described morphologically and compared withT. chilonis Ishii andT. evanescens Westwood as both present similarities with this species.T. cordubensis can be distinguished in the male genitalia by the shape of the dorsal expansion of the gonobase and the size, shape and relative position of the median ventral projection. Male antennal setae are longer inT. cordubensis than in the other 2 species. In addition, unlikeT. chilonis andT. evanescens, T. cordubensis is thelytokous at 20°C. in our laboratory, though males and gynandromorphs can be obtained by altering the rearing temperature, this being another difference of this species.     

Effect of tween 80 on exploratory behavior and locomotor activity in rats

Exploratory behavior and locomotor activity is enhanced in male rat pups (aged 10 to 20 days) whose dams received a chronic dose (1.25 ml/l) of Tween 80 via their drinking water. This enhancement manifests itself during the diurnal period of the day. These data suggest that Tween 80 has an effect on the CNS which could lead to misinterpretation of results in toxicology studies that use this compound as a dosage vehicle.     

Raman and infrared spectra of toxin gamma from the venom of the scorpion Tityus serrulatus

Toxin gamma is a basic, low-molecular-weight, neurotoxic protein, isolated from the venom of the Brazilian scorpion, Tityus serrulatus. Raman spectra (400-1800 cm-1 region) of this toxin in both the lyophilized state and in 0.1 M acetate buffer (pH 4.5) and the infrared spectrum (700-4000 cm-1 region) of a solid film were investigated. From the vibrational spectra, it can be concluded that the polypeptide backbone of toxin gamma consists of a mixture of the different secondary structures, with predominance of beta-sheet, followed by unordered structure and alpha-helix, with some evidence of beta-turn structures. The four disulfide bridges assume the gauche-gauche-gauche conformation of the CCSSCC fragments. The intensity ratio of the doublet at 853 and 828 cm-1 suggests that four out of the five tyrosine residues are exposed. The three tryptophan residues are exposed on the surface, and the single methionine residue assume the gauche-gauche conformation. Toxin gamma retains full activity in the pH 4.5-7.5 range, but is almost completely inactivated at pH 11.5.     

Transfer of N, N'-diacetylchitobiose from dolichyl diphosphate into a gray matter membrane glycoprotein

Gray matter and white matter membranes catalyze the transfer of label from UDP-N-acetyl-[${}^{14}\text{C}$] glucosamine into N-acetyl[${}^{14}\text{C}$]glucosaminyl-pyrophosphoryl-dolichol, N,N′-diacetyl [${}^{14}\text{C}$]chitobiosyl-pyrophosphoryl-dolichol, and N-acetyl[${}^{14}\text{C}$]glucosamine-labeled glycoprotein. Gel filtration of the Pronase digests of gray matter N-acetyl[${}^{14}\text{C}$]glucosamine-labeled glycoprotein reveals two N-acetyl[${}^{14}\text{C}$]glucosamine-labeled glycopeptide fractions. One fraction (A) contains approximately eight glycose units. All of the radioactivity is at nonreducing termini and can be released by treatment with an exo-β-N-acetylglucosaminidase. A smaller N-acetyl[${}^{14}\text{C}$]glucosamine-labeled glycopeptide (B) is recovered in the elution volume expected for an asparaginyl disaccharide. Structural studies show that the labeled saccharide unit in glycopeptide B is N,N′-diacetyl[${}^{14}\text{C}$]chitobiose. The linkage between the ${}^{14}\text{C}$-labeled disaccharide and the polypeptide has the properties of an N-glycosidic attachment to asparagine. Only the larger N-acetyl[${}^{14}\text{C}$]glucosamine-labeled glycopeptide (A) is found in Pronase digests of white matter membrane N-acetyl[${}^{14}\text{C}$]glucosamine-labeled glycoprotein after incubation with UDP-N-acetyl[${}^{14}\text{C}$]glucosamine. When gray matter membranes are incubated with UDP-N-acetyl[${}^{14}\text{C}$]glucosamine in the presence of tunicamycin or UMP, the labeling of glycolipid and the asparaginyl disaccharide is inhibited. UMP and tunicamycin have no effect on the transfer of N-acetyl[${}^{14}\text{C}$]glucosamine to external acceptor sites of the larger glycopeptide (A). The transfer of N,N′-diacetyl[${}^{14}\text{C}$]-chitobiose from carrier lipid to protein is observed when extensively washed membranes containing endogenous, prelabeled ${}^{14}\text{C}$-labeled glycolipids are incubated in the presence or absence of unlabeled GDP-mannose. UMP treatment of the prelabeled membranes selectively discharged over 80% of the label from N-acetyl[${}^{14}\text{C}$]glucosaminyl-pyrophosphoryl-dolichol, but had no effect on the transfer of the ${}^{14}\text{C}$-labeled disaccharide to protein. All of these results are concordant with transfer of N,N′-diacetylchitobiose from dolichyl diphosphate to gray matter glycoprotein. The major membrane glycoprotein labeled by the lipid-mediated [${}^{14}\text{C}$]disaccharide transfer reaction has an apparent molecular weight of 24,000. Tunicamycin prevents the enzymatic labeling of the gray matter glycoprotein having an apparent molecular weight of 24,000.     

The inhibition of phospholipase A2 by manoalide and manoalide analogues

Manoalide, a natural product from sponge, displays anti-inflammatory activity in vivo. Previous work has shown that manoalide is also a potent covalent inhibitor of the extracellular phospholipase A2 from cobra venom and that the inhibition correlated with a pH-dependent change in manoalide (Lombardo and Dennis (1985) J. Biol. Chem. 260, 7234-7240). Manoalide contains two rings and the opening of either would produce an alpha,beta-unsaturated aldehyde. The cobra venom phospholipase A2 may be able to catalyze the opening or isomerization of one of these rings, raising the possibility that manoalide is acting as a suicide substrate. To ascertain the role of the gamma-lactone ring in the inhibition, we have now investigated a synthetic manoalide analogue, 3(cis,cis-7,10)-hexadecadienyl-4-hydroxy-2-butenolide (HDHB) which contains only the alpha,beta-unsaturated gamma-lactone ring. We have found that the closed and open forms are in rapid equilibrium between pH 4 and 9 with the cyclic form being preferred at acidic pH values and the open cis form preferred at pH 9.5. When the pH is raised above 12, the alpha,beta double bond isomerizes to form trans-HDHB. Once the trans compound is formed, it is stable at all pH values and does not recyclize to the gamma-lactone ring. The observed pKa of 7.7 found for the inhibition of manoalide agrees well with the transition of the closed to the cis form of the gamma-lactone ring. Kinetic experiments with the HDHB compound show that under conditions in which the cis and closed form of the inhibitor are present in equal molar ratios, HDHB is not an irreversible inhibitor, but reversibly competes with substrate. However, the kinetics of this inhibition are complex and do not follow either pure competitive or non-competitive inhibition. The trans-HDHB exhibits similar complex kinetic but is several times more potent. The distinct differences between the behavior of manoalide and HDHB clearly indicate that while the gamma-lactone ring may play an important role in manoalide inhibition, it alone does not produce irreversible inhibition.