Induction of neuronal type nitric oxide synthase in skeletal muscle by chronic electrical stimulation in vivo

Reiser, Peter J., William O. Kline, and Pal L. Vaghy.Induction of neuronal type nitric oxide synthase in skeletal muscle by chronic electrical stimulation in vivo. J. Appl. Physiol. 82(4): 1250-1255, 1997.Fast-twitch skeletal muscles contain more neuronal-type nitricoxide synthase (nNOS) than slow-twitch muscles because nNOS is presentonly in fast (type II) muscle fibers. Chronic in vivo electricalstimulation of tibialis anterior and extensor digitorum longus musclesof rabbits was used as a method of inducing fast-to-slow fiber typetransformation. We have studied whether an increase in musclecontractile activity induced by electrical stimulation alters nNOSexpression, and if so, whether the nNOS expression decreases to thelevels present in slow muscles. Changes in the expression of myosinheavy chain isoforms and maximum velocity of shortening of skinnedfibers indicated characteristic fast-to-slow fiber type transformationafter 3 wk of stimulation. At the same time, activity of NOS doubled inthe stimulated muscles, and this correlated with an increase in theexpression of nNOS shown by immunoblot analysis. These data suggestthat nNOS expression in skeletal muscle is regulated by muscle activityand that this regulation does not necessarily follow the fast-twitchand slow-twitch pattern during the dynamic phase of phenotypetransformation.

     

A new mutation protocol for obtaining auxotrophic mutants of the yeastPhaffia rhodozyma

Summary A new mutation strategy, which involves -irradiation of cells followed by a selective enzymatic enrichment step, was worked out to obtain auxotrophic mutants from the astaxanthin-producing yeast P. rhodozyma. Under the optimized conditions described, different mutants suitable for strain improvement were isolated.     

Concentration of iron and manganese in rice plants as influenced by hexachlorocyclohexane applied to soil

Summary Application of a granular formulation of hexachlorocyclohexane (HCH) to the potted soil at flooding decreased the concentration of iron and. to some extent, manganese in rice plants, especially at concentrations above 3 ppm active ingredient (a.i.) Likewise, HCH, applied to rice fields at transplanting (several days after submergence) caused a significant decrease in the concentration of iron, and not manganese, in the rice plant but only at concentrations above 12.5 kg a.i./ha despite high levels of reduced iron in the soil. Inhibition of iron reduction by HCH was more pronounced when applied at flooding than at several days after flooding.     

Effect of the fungal toxin (zearalenone) on the reproductive system and fertility of male and female rats.

The fertility-inhibiting effects of long-term (8 weeks) consumption of maize infected with a fungus producing F2 toxin (zearalenone) was studied in adult male and female albino rats. The fertility rate was further decreased by 25-30% if the animals were kept on contaminated diet up to 14 weeks. The gonadal weight was decreased, follicular maturation and spermatogenesis were disturbed. The toxic diet consumed by mothers during pregnancy and lactation induced permanent changes in reproductive organs, disorders in vaginal cyclicity and disturbed fertility in the offspring. Neonatal administration of purified F2 toxin provoked similar changes. It is suggested that this fungal toxin may cause sterility syndrome in the offspring, similar to that produced by androgen or estrogen administration.     

A study of the pollen grains of Amaranthus spinosus Linné and A. Dubius Mart ex Thellung and their hybrids

A pollen-morphology study of Amaranthus spinosus, A. dubius, and their hybrids has been carried out. Three pollen types have been observed, namely (1) Type A: micrograins; (2) Type B: grains with smaller pores; and (3) Type C: grains with larger pores. Type B is characteristic of A. spinosus, Type C of A. dubius, and the micrograins of the hybrids. Pollen size range, and frequency of the various morphotypes serve to throw light on the biosystematics of the plants studied.     

Embryo culture of Costus speciosus (Koen.) Sm. to regenerate variable diosgenin yielding clones

Mature embryos of Costus speciosus were excised and cultured on Schenk and Hildebrandt's (1972) nutrient medium containing auxins and cytokinins either alone or in combination. Multiple shoots were obtained when kinetin and indole-3-butyric acid were supplemented each at 0.1 mg 1^–1 concentration. Embryo-derived plantlets were multiplied through propagation of rhizomes and the propagules derived from a single embryo were designated as an embryoclone. Twenty such embryo-clones were maintained in the field. Variations in rhizome biomass yield and diosgenin contents of these embryoclones were noted. Thirty-six percent of the embryo-clones studied were high diosgenin yielding types. Diosgenin contents at the intraclonal level were uniform. The in vitro raised plants were morphologically uniform and indistinguishable from their parent.Abbreviations SH Schenk and Hildebrandt (1972) medium - Kn kinetin - BAP 6-benzylaminopurine - 2,4-D 2,4-dichlorophenoxyacetic acid - NAA 1-naphthaleneacetic acid - IBA indole-3-butyric acid - IAA indole-3-acetic acid - CA casaminoacids (vitamin free) - TLC thin layer chromatography     

Hemoglobins,XLVIIII

Summary Hagfish hemoglobin has three main components, one of which is Hb III. It is monomeric and consists of 148 amino acid residues (M = 17 350). Its complete primary structure, previously published, is discussed here. The proximal amino acid (F8) of the heme linkage is histidine as always in the hemoglobins, but the regularly expected distal histidine E7 is substituted by glutamine. This substitution, leading to a new kind of heme linkage, has hitherto only been demonstrated in opossum hemoglobin. It is suggested that E7, Gln, is directed out of the heme pocket, and that the adjacent Ell, Ile, is directed toward the inside of the pocket, giving the distal heme contact instead of histidine.Myxine Hb III has an additional tail of 9 amino acid residues at its N-terminal end, as has the hemoglobin ofLampetra fluviatilis. The genetic codes ofMyxine andLampetra hemoglobins show 117 differences, in spite of many morphological resemblances between hagfish and lamprey. Their primary hemoglobin structures show differences substantial enough to bo compatible with the divergence of the two families some 400–500 million years ago.     

The circular dichroism of lysozyme.

The circular dichroism spectra of hen egg white lysozyme, and of lysozyme derivatives in which tryptophan residues 62 or 108, or both, are selectively oxidized, have been measured as a function of pH over the range of 200 to 310 nm. Neither Trp-62 nor Trp-108 is principally responsible for the positive rotational strength in the 280 to 300 nm region. The spectrum in the 200 to 230 nm region is nearly the same in the native protein and in the derivatives, and is little affected by binding of saccharide. These results are used to reinterpret the circular dichroism spectra of the lysozymes and alpha-lactalbumins.     

Phytotoxic effects of β-pinene on early growth and associated biochemical changes in rice

β-Pinene, an oxygenated monoterpene, is one of the major monoterpenes emitted into the atmosphere from forest areas and trees. Besides, it is a principal component of essential oils of a number of aromatic plants, which are involved in a variety of ecological interactions, including allelopathy, in the natural environment. However, studies pertaining to phytotoxicity and biochemical effect(s) of β-pinene are largely lacking. We investigated the effect of β-pinene (0.02, 0.04, 0.08, 0.20, 0.40 and 0.80 mg/ml) in a dose- and time-dependent manner on early seedling growth, dry weight accumulation, photosynthetic pigments and changes in macromolecule (protein and carbohydrate) content and activities of enzymes—proteases, α- and β-amylases, polyphenol oxidases and peroxidases- in rice (Oryza sativa) after 3rd, 5th and 7th day of exposure. β-pinene (≥0.04 mg/ml) significantly reduced the root (by 13–87%) and coleoptile (by 5–80%) length of rice. Exposure to β-pinene reduced total chlorophyll content in rice coleoptiles suggesting a negative impact on photosynthesis. The content of macromolecules (proteins and carbohydrates) enhanced significantly in response to β-pinene, whereas the activities of hydrolyzing enzymes—proteases, α-amylases, and β-amylases—declined (by 30–85, 26–84, 27–74%, respectively) in β-pinene-exposed seedlings. In contrast, the activities of peroxidases (POX) and polyphenol oxidases (PPO) enhanced significantly (by 16–152 and 53–290%, respectively) in rice roots in response to β-pinene in a dose- and time-dependent manner. Increased activities of POX and PPO indicate their involvement in providing protection and/or conferring resistance against β-pinene-induced stress. The study concludes that β-pinene inhibits the early growth of rice by altering the plant biochemical status and enhancing activities of POXs and PPOs involved in general plant defense.