Calcium-dependent prolonged effects on melanophores of [4-norleucine, 7-D-phenylalanine]-alpha-melanotropin.

A single injection of the melanotropin analog [4-norleucine, 7-D-phenylalanine]-alpha-melanotropin into frogs (Rana pipiens) caused near maximum darkening of the skins of the frogs for at least 6 weeks. Injections of the natural hormone alpha-melanotropin or of the analog [Nle4]-alpha-melanotropin also caused darkening, but this effect lasted only a few days. Morphological examination of the skins of frogs injected with [Nle4, D-Phe7]-alpha-melanotropin revealed that both dermal and epidermal melanophores were dispersed during the entire 6-week period.

Racemization effects on melanocyte-stimulating hormones and related peptides.

Heat-alkali treatment of synthetic alpha- and beta-melanocyte-stimulating hormones (MSH), known to cause racemization of amino acids within the peptides, results in prolongation of the darkening (melanophore dispersion) effect of these hormones on frog and lizard skins in vitro. Skins remain darkened for hours or even days if supramaximal concentrations of the racemized hormones are used. This response can be partially reversed by melatonin or noradrenaline.

Aryl hydrocarbon hydroxylase (AHH) induction by polybrominated biphenyls (PBBs): enchancement by photolysis.

Irradiation of the commercial polybrominated biphenyl (PBB( mixture, fireMaster BP-6, in cyclohexane solution at 300 nm for 930 min resulted in a marked diminution of the major components of the mixture. Administration of the photolyzed PBB mixture of fireMaster BP-6 to immature male Wistar rats caused both dose-related decreases in thymus weight and increase in hepatic microsomal benzo[a]pyrene hydroxylase (AHH), 4-dimethylaminoantipyrine N-demethylase and NADPH-cytochrome c reductase activities and cytochrome P-450 content. The dose effecting half-maximal AHH induction for the photolyzed PBBs (9 mg .

Biological actions of melanocyte-stimulating hormone.

Melanocyte-stimulating hormone (alpha-melanotropin, MSH) may function in a number of diverse physiological roles. MSH stimulates (1) rapid translocation of melanosomes (melanin granules) in dermal melanophores to effect rapid colour change and (2) melanogenesis in normal and abnormal (melanoma) epidermal melanocytes. Both actions involve (1) initial binding of the peptide on the melanocyte membrane, (2) transduction of signal to adenylate cyclase, and (3) increased cytosolic levels of cyclic AMP.

Synthesis and structure-function studies of melanocyte stimulating hormone analogues modified in the 2 and 4(7) positions: comparison of activities on frog skin melanophores and melanoma adenylate cyclase.

The synthesis and purification of several analogues of the melanotropins with amino acid substitutions at the tyrosine-2 and methionine-4(7) positions are reported. The compounds synthesized included [4-norleucine]-alpha-MSH, [7-norleucine]-beta p-MSH, [2-3',5'-diiodotyrosine]-alpha-MSH, [2-D-tyrosine]-alpha-MSH, and [2-phenylalanine,4-norleucine]-alpha-MSH. The biological activities of these derivatives were measured and compared on normal melanocytes (frog skins) and on transformed melanocytes (mouse melanoma adenylate cyclase), over the entire dose-response range.

4-Norleucine, 7-D-phenylalanine-alpha-melanocyte-stimulating hormone: a highly potent alpha-melanotropin with ultralong biological activity.

alpha-Melanocyte-stimulating hormone (alpha-MSH) reversibly darkens frog skins by stimulating melanosome movement (dispersion) within melanophores. Heat-alkali treatment of alpha-MSH results in prolonged biological activity of the hormone. Quantitative gas chromatographic analysis of the hydrolyzed heat-alkali-treated peptide revealed partial racemization particularly at the 4(methionine) and 7(phenylalanine) positions.

Selection for agonistic behavior in wild female mice.

This article reports the results of 11 generations of selective breeding for isolation-induced, interfemale aggression in Mus musculus. Within-family selection was used to form two high, two low, and two unselected control lines, beginning with a population of wild-trapped mice. Selection was successful in establishing the divergent lines, so that in recent generations about 50% of high-line animals attack, as do 25% of controls and 5% of lows.

Correlated characters in selection for aggressiveness in female mice. II. Maternal aggressiveness.

The present study investigated whether maternal aggression has shown a correlated response in a program of artificial selection for isolation-induced interfemale aggression in housemice. Females from the first replicate of lines (H1, C1, L1) and the second replicate of lines (H2, C2, L2) from generation S5 were given daily aggression tests for 20 consecutive days following the birth of their first litter. Evidence of a correlated response was found for replicate 2, but results for replicate 1 provided no evidence of a correlated response.

Purification and mechanism of action of macromomycin.

Macromomycin (MCR), a polypeptide antibiotic previously shown to have antitumor activity in experimental tumors, has been purified into an electrophoretically homogeneous component with an approximate molecular weight of 12,500. MCR has alanine as an NH2-terminal amino acid, 4 cysteine residues, and no arginine or methionine residues. With a fluorescence assay and agarose gel electrophoresis, MCR was shown to induce strand breaks in PM2 DNA in vitro.

Henneguya sp. (Cnidospora:Myxosporida) parasitic in the heart of the bluefish, Pomatomus saltatrix.

A myxosporidan parasite, Henneguya sp., was discovered in the bulbus and truncus arteriosus of bluefish, Pomatomus saltatrix. Infected fish were captured from the Atlantic Ocean near Montauk Point, Long Island, New York, Raritan Bay, New Jersey, and Chesapeake Bay, Maryland.

Forward and reverse mutations affecting the kinetics and apparent molecular weight of mammalian HGPRT.

Chinese hamster cells selected for resistance to 8-azaguanine following mutagenesis have hypoxanthine-guanine phosphoribosyltransferase (HGPRT; E.C. 2.

Pathogenic amoebas from brackish and ocean sediments, with a description of Acanthamoeba hatchetti, n. sp.

Acanthamoeba culbertsoni was isolated from a sewage-spoil dump site near Ambrose Light, New York Bight. A second species, Acanthamoeba hatchetti, n. sp.

Verbal discrimination reversal in a whole/part re-pairing transfer paradigm.

Whole/part transfer and re-pairing of rights and wrongs were employed in a study of verbal discrimination reversal learning. The whole/part and re-pairing procedures were used to create reversal conditions (0%, 50%, or 100% reversal) that were similar at the outset of reversal learning in that all correct alternatives on the reversal list were higher in situational frequency than their respective incorrect alternatives. Similarly, reversal lists were constructed that were similar in that all incorrect alternatives on the reversal list were higher in situational frequency than their respective correct alternatives.