Role of ovary-inhibiting hormone from eyestalks of marine penaeid prawns (Parapenaeopsis hardwickii) during ovarian developmental cycle

The activity of the ovary-inhibiting hormone in the eyestalks of female prawns, Parapenaeopsis hardwickii, was determined during its ovarian developmental cycle. In the inactive (stage I) and post-spawned phases of ovarian development, the ovary-inhibiting hormone activity was found to be very high. During the phase of full vitellogenesis (stage IV), the inhibiting activity is almost negligible. After spawning (stage V) it is present, but at a lower level than during inactive and post-spawned phases. Hence it is inferred that ovary-inhibiting hormone appears to be responsible for the phase of ovarian quiescence and to control the rate of vitellogenesis.     

Experimental pathogenicity of reovirus 13p2 for juvenile American oysters Crassostrea virginica (Gmelin) and bluegill fingerlings Lepomis macrochirus (Rafinesque)

Abstract. A viral agent (13p₂), isolated from clinically normal juvenile American oysters ( Crassostrea virginica ) and characterized as a new serotype of reovirus, was tested to determine if it could replicate and produce disease in experimental juvenile oysters. Because the virus replicated well in the bluegill fry (BF-2) fish cell line, fingerling bluegills Lepomis macrochirus were included in the pathogenicity experiments. Exposure of oysters to the 13p₂ virus in ambient seawater resulted in no significant mortality and no increased virus titres or histological lesions. Virus particles were not observed in tissues of exposed oysters when examined with transmission electron microscopy (TEM). Intraperitoneal inoculation of the 13p₂ virus into bluegills resulted in 44% mortality associated with a focal necrotic hepatitis. Evidence of virus replication, when evaluated histological or by virus titration, was observed in 94% of 32 inoculated fish. Samples of infected livers examined with TEM revealed typical cytoplasmic arrays of 13p₂ virus particles in affected hepatocytes. Rising virus titres and hepatic lesions also occurred in bluegills exposed to water containing the 13p₂ virus. These results indicated the natural host of the 13p₂ virus was not the American oyster, but that it was a significant pathogen for at least one fish species.     

Gas-liquid chromatographic determination of monosodium glutamate in soups and soup bases.

A method is given for determining monosodium glutamate (MSG) in soups and soup bases by gas-liquid chromatography (GLC) of the trimethylsilyl ether derivative of glutamic acid. This method compared favorably with existing methods including GLC of the trifluoroacetate (TFA)/butyl ester derivative, and analysis on an amino acid analyzer. In addition, some samples were analyzed by GLC/mass spectrometry. The MSG content of various products ranged from approximately 0.2% in some condensed soups to 13.1% on bouillon cubes. The method, which can detect as little as 0.05%, requires only a 10 min single step derivatization at room temperature and is preferred to the TFA/butyl ester technique.     

Degradation of ioxynil by a soil fungus, Fusarium solani

A fungus, Fusarium solani, isolated from the soil, degraded ioxynil (3,5-diiodo-4-hydroxyben-zonitrile) in pure culture into at least eight products. Five products were detected in the organic fractions extracted from a culture grown in [¹⁴C]cyano-labeled ioxynil. Three additional products were separated by ion-exchange chromatography of the acidified aqueous phase. Cultures grown in the presence of [¹⁴C]ring-labeled ioxynil produced the same products in the organic extract and four to five products in the aqueous phase. The cyano-carbon of ioxynil was released as CO₂ at a faster rate than that of ring-carbons and was released after the initial ring cleavage. Two of the metabolites were identified as 3,5-diiodo-4-hydroxybenzamide and 3,5-diiodo-4-hydroxybenzoic acid.     

A method for measuring adenosine triphosphate in soil

A method was devised for the extraction and measurement of adenosine 5'-triphosphate (ATP) in soil that minimizes sorption of ATP on the soil colloids. Soil was ultrasonified for 1 min with a solution containing trichloracetic acid (0.5 m). disodium hydrogen orthophosphate (0.25 m) and paraquat dichloride (0.1 m). The ATP content of the filtered extract was determined without further treatment in a scintillation spectrometer by the firefly luciferin-luciferase system. Recovery of added ATP was greater using the extratant containing trichloracetic acid, orthophosphate and paraquat than with trichloracetic acid alone or with a sulphuric acid extradant. Recoveries of added ATP ranged from 45% to 84% in thirteen different soils; ATP contents from 0.64 to 9.03 μg g^?1 soil.     

Interactions between bacteria and ectomycorrhizal fungi

Interactions between eight ectomycorrhizal fungi and eight bacteria were tested on five laboratory media and in the rhizoplane of Pinus radiata. Depression of growth of the fungi by the bacteria in laboratory media was dependent on the medium and bore little relation to effects in the rhizoplane. In the rhizoplane, different bacteria could depress, have no effect or even stimulate growth of mycorrhizal fungi. Competition and antagonism are suggested as mechanisms for depression of the fungi. Some bacteria gave protection against the depressive effects of other bacteria. Considerable differences occurred between ectomycorrhizal fungi in their colonization of the rhizoplane in the absence of bacteria and also in their presence. The common mycorrhizal fungi Rhizopogon luteolus and Thelephora terrestris generally colonized roots well but the strain of Pisolithus tinctorius studied colonized poorly. Direct microscopy showed the percentage cover of the root by microorganisms was usually only 10–20%.It is proposed that interactions of ectomycorrhizal fungi with soil organisms are important in determining the successful introduction and persistence of inoculated ectomycorrhizal fungi. Fungi should be selected for compatibility with a wide range of soil microflora as well as efficiency in plant stimulation.     

Distribution and partial characterisation of acid hydrolysable organic nitrogen in six New Zealand soils

Six New Zealand topsoils of widely different origins and properties were subjected to 6m HC1 hydrolysis and the distribution of N fractions and amino acids were determined qualitatively and quantitatively.Of the total-N in the soils studied 83–91%, was hydrolysable with 6m HCl. The largest proportion of the hydrolysable N was α-amino acid N (38– 42%). followed by hydrolysable-unknown N (HUN) (14–24%), and NH₄⁺-N (14–22%). A significant proportion (25–50%) of the HUN fraction was accounted for by the non α-amino acid-N. Oxidative (3% H₂O₂) hydrolysis released N-phenoxy amino acid-N and possibly N-compounds which were complexed with phenols and sugars. All soils had a similar amino-acid composition with a predominance of acidic amino-acids.     

Colonization by Rhizobia of the seed and roots of legumes in relation to exudation of phenolics

A study of the colonization pattern of Rhizobium inoculated either in the soil or on to the seeds of green gram (Phaseolus aureus Roxb.), black gram (P. mungo L.) and sun hemp (Crotalaria juncea L.) revealed a significant reduction of Rhizobium in the spermosphere of sun hemp which was attributed to excretion of phenolic compounds by the seed. As the plants aged, the quantity of phenolics exuded by the roots was reduced and there was a parallel increase in the Rhizobium population in the rhizospheres of the three plant species.     

Cellular immune response in rainbow trout Salmo gairdneri Richardson to Yersinia ruckeri O-antigen monitored by the passive haemolytic plaque assay test

Abstract. The specificity and kinetics of the immune response of rainbow trout ( Salmo gairdneri ) to single injections of an O-antigen extracted from the bacterial pathogen Yersinia ruckeri , which causes enteric redmouth in fish, were investigated by the passive haemolytic plaque assay and serum antibody quantitation. Doses ranging from 5 ng to 500 mg in 10-fold increments were injected intraperitoneally into groups of trout held at 17 × 1°5°C. The occurrence of plaque forming cells (PFC) and humoral antibody was followed for 35 days after injection. Trout gave an immune response to doses of 500 ng and above. Seven days after injection no humoral antibody was detected, but PFC were found in the spleen. The maximum PFC numbers occurred 11 days after injection. On day 21, few PFC were found, whereas serum antibody titres were highest. The antibody from immunized trout showed little or no cross-reactions with sheep red blood cells passively labelled With antigens from other fish pathogens.     

Photoperiod induced off-season spawning of pink salmon (Oncorhynchus gorbuscha)

Four groups of pink salmon, which had been reared under artificial light, became sexually mature and produced viable gametes: 59 days prior to, and 19 – 32 days, 115 days and 220 days after their expected date of reaching sexual maturity. Altered times of sexual maturation were obtained by accelerating, leaving unchanged, or decelerating the rate of change of photoperiod which each group of fish would normally receive during its first year of life. All groups of fish were exposed to a normal rate of change in photoperiod during their final year of life. Mean fecundity was reduced from the 800–2000 ova observed in wild stocks, and ranged from 629 for the 59 day advanced fish, to 862 for the 115 day delayed fish. Egg mortality during the period from fertilization to eyeing was much greater in the three groups of fish subjected to accelerated or decelerated rates of change in photoperiod than in the fish subjected to the normal rate of change in photoperiod. Some of the progeny of the 220 day delayed fish, which were reared under artificial light with the normal rate of change in photoperiod set 220 days out-of-phase, became sexually mature 2 years after they had begun life as fertilized eggs.