External and internal sexual dimorphism in leiognathid fishes: morphological evidence for sex-specific bioluminescent signaling

Fourteen species of leiognathid fishes (Perciformes, Leiognathidae) from the Philippine Islands, Thailand, Japan, Indonesia, and Palau were examined for accessory secondary sexual dimorphism. Thirteen species exhibit either external dimorphism (a clear patch of skin on the flanks of males, a large clear patch of skin on the opercular margins of males, or a flank stripe in males) or internal dimorphism (large light organs in males) or both. Eight of the 14 species (and possibly as many as 11) exhibit both forms of sexual dimorphism. Two species show only internal light organ volume dimorphism, and one species shows neither external nor internal dimorphism. Sexual dimorphism is thus very common in leiognathids. The externally dimorphic skin patches are closely associated with the internally dimorphic light organ system in seven species (and possibly as many as ten), indicating a potential for light emission through the clear patches. A bioluminescent signaling function by males is therefore suggested for the sexual dimorphism in leiognathids, which may play an important role in the schooling behavior as well as in species and sexual recognition of these coastal fishes.     

Effects of concanavalin A and cholera toxin on epidermal cAMP and migration rate during wound closure in adult newts

Following removal of a skin patch from each hind limb of a series of adult newts, the limbs were explanted into small dishes of Holtfreter solution containing various combinations of test drugs. Later, the amount of wound epithelium that formed on each limb was determined using a planimeter on wound tracings obtained with the aid of a drawing tube-equipped microscope. Exposure of migrating cells to the plant lectin, concanavalin A (con A), lowered cyclic AMP (cAMP) levels and depressed migration. Exposure to cholera toxin and theophylline (CTX) significantly elevated cAMP levels and significantly depressed migration rate. Exposure of CTX-treated cells to con A tended to lower CTX-elevated cAMP levels while depressing the migration rate well beyond the depression caused by CTX alone. These results provide further evidence that cAMP can regulate the rate of newt epidermal cell migration. They also show that the inhibitory effect of con A on motility in these cells is independent of its effects on cAMP.     

The effect of calf removal on estrous response and pregnancy rate of beef cows after SYNCRO-MATE-B treatment

The effect of calf removal on estrous response and pregnancy rate of cows given SYNCRO-MATE-B (SMB) was determined. Two hundred forty three lactating beef cows treated with SMB were allotted to three treatments: treatment 1, no calf removal; treatment 2, 24 hr calf removal and treatment 3, 48 hr calf removal. Calf removal time began with removal of the SMB implant. All cows were artificially inseminated 48 to 54 hr after implant removal. Body condition of cows in each heard was visually appraised as adequate or marginal. At each location, technicians and sires were stratified across all treatments.Estrous response of cows (n=143) was different (P<.01) between treatments which averaged 23, 40 and 77 percent for treatments 1, 2 and 3, respectively. Pregnancy rates of cows (n=243) after the first artificial insemination (AI) were 32, 28 and 46 percent for treatments 1, 2 and 3, respectively. The pregnancy rate was greater (P<.05) for treatment 3 than other treatments. After 25 days of breeding, the pregnancy rates were 59, 58 and 72 percent, respectively, for the three treatments. There was a linear relationship between days postpartum at the time of treatment and estrous response (P<.01) and first service pregnancy rate (P<.05). The partial regression coefficients for estrous response and first service pregnancy rate were 1.2 and .6 percent, respectively.In summary, estrous response and pregnancy rate of lactating beef cows treated with SMB were increased by 48 hr calf removal, compared to no calf removal or 24 hr calf removal, when calf removal time began with removal of the SMB implant.     

Genomic analysis of heavy metal-resistant Halobacterium salinarum isolated from Sfax solar saltern sediments

Extremophiles - We studied the fungal DNA present in a lake sediment core obtained from Trinity Peninsula, Hope Bay, north-eastern Antarctic Peninsula, using metabarcoding through high-throughput...     

Characterization of the parameters affecting covalent binding stoichiometry in binary and ternary complexes of thymidylate synthase

Covalent binding stoichiometries for both the enzyme:5-fluoro-2'-deoxyuridine 5'-monophosphate (FdUMP) binary complex and the enzyme:FdUMP:5,10-methylenetetrahydrofolate (inhibitory ternary) complex at equilibrium were measured by the trichloroacetic acid precipitation assay and shown to be a function of temperature, time, pH, salt concentration, buffer composition and thiol concentration. Incubation at 37 degrees C yielded the maximum covalent binding ratio (mol FdUMP/mol enzyme) for the latter binary (0.7) and ternary (1.7) complexes. In most buffers studied, the maximum covalent binding ratio (1.5-1.7) for the inhibitory ternary complex occurred over a broad pH range (4.5-8.0), while the optimum covalent binding ratio for binary complex was observed at a much narrower region centered between pH 5.5-6.5. In the presence of increasing concentrations of phosphate buffer, the maximum binding ratio for the covalent binary complex decreased from 0.63 in the absence of phosphate to 0.1 in the presence of 225 mM phosphate, while that for the inhibitory ternary complex was unchanged. When a ternary complex was formed with enzyme, FdUMP and (+/-)-tetrahydrofolate in the absence of phosphate, the FdUMP:enzyme covalent binding ratio was 1.8, while in the presence of 75 mM phosphate, the binding ratio was only 1.0. When exogenous thiol was removed by centrifugal column chromatography, the maximum binding stoichiometry of the resulting inhibitory ternary complex was 1.7 and was independent of added thiol over a 2 h incubation period at 37 degrees C. When extensive dialysis at 5 degrees C was used to remove the thiol, the maximum binding stoichiometry of the resulting inhibitory ternary complex was found to be dependent on both the concentration of added thiol and the time of incubation at 37 degrees C and did not exceed a value of 1.0.     

The peep vocalization in group reared chicks (Gallus domesticus): Its relation to fear

The relation of fear and arousal to peeping in socially-reared chicks was investigated in a series of four experiments. Pre-test exposure to loud noise or shock resulted in decreased peeping in chicks tested in isolation, while in the presence of a mirror, pre-test exposure to loud noise reduced peeping, but pre-test shock had no effect. It was also shown that neither transquilizer (Pacitran) ingestion nor experimenter proximity had any significant influence on peeping. An inverse relationship between peeping and activity latency was also revealed in these experiments, and peeping was usually found to precede the initiation of activity. The relationship between fear and the peep vocalization of sociallyreared chicks is discussed.     

Characterization of ethylene/gibberellic acid control of germination in Lactuca sativa L.

Ethylene production during germination of lettuce seeds (Lactucasativa L., cv. Premier Great Lakes) occurred at two distinctlydifferent rates. A very low rate of ethylene release was observedprior to the 12th hour of incubation at 22?C. The rate of ethyleneproduction, however, increased 100 fold between the 12th and16th hour of incubation. This high rate of ethylene productiononly occurred in the presence of seeds which exhibited a visibleprotrusion of the radicle. The duration of exposure to a supraoptimaltemperature (32?C) was inversely proportional to the percentgermination at 32?C. Ethylene production and growth were notblocked by incubating visibly germinated seeds at 32?C. Exogenous ethylene partially restored germination at 32?C, butonly in the light. Gibberellic acid partially substituted forthe induced light requirement but not for ethylene. It was concludedthat the supraoptimal temperature raised the threshold concentrationof ethylene required for germination. This threshold requirementwas satisfied in the presence of exogenous ethylene. Germinationat 32?C was abo dependent upon the presence of GA. With exogenousethylene present, the GA-mediated system was presumably reinstatedor bypassed by exposing the seeds to either light or GA. Theinitial low rate of ethylene production apparently regulatessubsequent germination but only when present at a minimum thresholdconcentration. Those events initiating germination have obviouslyoccurred prior to the time of radicle emergence. Post-germinationethylene production, therefore, did not break thermodormancy,but occurred simultaneously with radicle emergence. (Received November 29, 1976; )