FMRFamide-like immunoreactivity within the nervous system of the nematodes Panagrellus redivius, Caenorhabditis elegans and Heterodera glycines

A polyclonal antiserum raised against the molluscan neuromodulatory peptide Phe-Met-Arg-Phe-amide (FMRFamide) reacts with nervous tissue in the free-living nematodes Panagrellus redivius and Caenorhabditis elegans and in infective juveniles (J₂) of the soybean cyst nematode Heterodera glycines . Sectioning of the nematodes was unnecessary but penetration of the antibody was improved by cutting the animals or by use of plasma etching to breach the cuticle before incubation in antiserum. Both procedures required subsequent exposure to detergents or partial digestion with protease K for optimum immunoreactivity. A positive reaction was observed for all three nematodes in the longitudinal nerve cords, nerve ring and ventral and lateral ganglia. Neurones were also visualized in association with the vulva in the free-living species and the spicules of male P. redivius . In H. glycines , neurones innervating the pharynx reacted positively, as did two loops of neural tissue on either side of the ventral nerve cord slightly anterior to the anus. Immunoreactivity was also noted in the amphidial pouches of H. glycines after prolonged (15 min) protease treatment. Further work is needed to establish the structure of the peptide antigen localized in these nematodes.     

Winter and summer upwelling modes and their biological importance in the California Current Ecosystem

Analysis of monthly coastal upwelling intensities revealed two seasonal and biologically relevant upwelling ‘modes’ in the California Current Ecosystem (CCE). The first mode reflected upwelling during the summer months and was characterized by low‐frequency (multidecadal) processes, including significant (P<0.01) linear trends at some latitudes. In contrast, the second mode reflected wintertime upwelling and was defined by higher‐frequency variability associated with the North Pacific High and El Niño Southern Oscillation events. These modes were compared with multidecadal time series of splitnose rockfish (Sebastes diploproa) otolith growth, yelloweye rockfish (S. ruberrimus) otolith growth, Chinook salmon (Oncorhynchus tshawytscha) scale growth, and indices of Cassin's auklet (Ptychoramphus aleuticus) and common murre (Uria aalge) reproduction in the central‐northern CCE. In redundancy and correlation analyses, salmon growth and Cassin's auklet fledgling success associated with the summer upwelling mode while all other time series associated with the winter upwelling mode, indicating that CCE biology was differentially sensitive to these seasonal upwelling patterns. Thus, upwelling occurred in unrelated seasonal modes with contrasting trends, atmospheric forcing mechanisms, and impacts on the biology of the CCE, underscoring the importance of seasonality when evaluating ecosystem response to climate variability and change.     

Synthesis of Sterols In Herpetomonas Samuelpessoai: Influence of Growth Conditions*

Ergosterol was the only sterol detected in Herpetomonas samuelpessoai grown in a defined, lipid-free medium. When cultivated in a complex medium, this flagellate was found to contain 6 additional sterols. As measured by incorporation of L-[Me-¹⁴C]methionine, in the absence of acetate, the sterol synthesis was greater at 28 C than at 37 C; in the presence of acetate, however, this synthesis was greater at 37 C. When [2-¹⁴C]acetate was used as the sterol precursor, the synthesis level at 37 C exceeded that at 28 C.     

Body mass and extinction risk in Australian marsupials: The ‘Critical Weight Range’ revisited

Australian mammals have suffered an exceptionally high rate of decline and extinction over the last two hundred years. Body mass is linked to extinction risk in Australian mammals, but the nature of this association is controversial. A widely held view is that species of intermediate body mass (between 35 and 5500 g, the ‘critical weight range’, CWR) have declined most severely. However, the existence of the CWR has been disputed. In this paper we clarify the relationship of decline status and body mass in Australian marsupials. We show that the form of this relationship differs for ground‐living versus arboreal species, and for species from low versus high rainfall areas. Among ground‐living species and those from low‐rainfall areas, declines were strongly size‐selective and concentrated on species within the CWR. For the remaining species, decline was only weakly related to body mass with no evidence of heightened risk for species of intermediate size. We conclude that for terrestrial species in low rainfall areas, species within the CWR are most at risk of decline and extinction.     

Verticillium wilt of pea (Pisum sativum)

A wilt disease of garden pea (Pisum sativum) caused by Verticillium dahliae is described and the range of pathogenicity of the isolate investigated. It is pathogenic to potato, sweet pea, antirrhinum and broad bean and isolates of V. dahliae from potato, lucerne and sweet pea and V. albo-atrum from lucerne are pathogenic to pea. Since the most common disease symptoms, acropetal progression of chlorosis and necrosis of the leaves followed by premature defoliation are indistinguishable from natural senescence, it is probable that disease and senescence symptoms are confused in the field. The premature defoliation results in marked reduction in green leaf area, leaf dry weight and pod yield.     

Effect of Temperature and Osmolarity on Growth of Crithidia fasciculata,C. hutneri,C. luciliae thermophila,and Herpetomonas samuelpessoai1

Crithidia fasciculata (Anopheles, Culex, and Nöller strains), C. hutneri, C. luciliae thermophila, and Herpetomonas samuelpessoai were grown in a defined medium with different values of osmolarity at different temperatures. C. fasciculata (all strains) grew best between 300 to 500 mOsm; H. samuelpessoai, 400–500 mOsm; and C. hutneri and C. luciliae thermophila, 500–800 mOsm. At higher temperatures better growth was obtained at the upper osmolarities.     

Leptomonas lactosovorans n. sp., a Lactose-Utilizing Trypanosomatid: Description and Nutritional Requirements1

Leptomonas lactosovorans n. sp. is described from the gut of the reduviid hemipteran Zelurus martinsi. It can be grown in a defined medium. The requirements for amino acids, vitamins, purine, and heme were similar to those established for Crithida fasciculata. Growth is stimulated by aeration. Generation time is longer than for any other insect trypanosomatid described; its utilization of lactose as a carbon source is a unique feature among trypanosomatids.     

Growth of Crithidia at High Temperature: Crithidia hutneri sp. n. and Crithidia luciliae thermophila s. sp. n.*

SYNOPSIS. Crithidia hutneri sp. n. and Crithidia luciliae thermophila s. sp. n. are described. Both flagellates can be grown in a defined medium over a temperature range of 15–37°C. The requirements for amino acids, vitamins, purine and hemin, and pH range were similar to those established for Crithidia fasciculata, although threonine was required as a growth factor for C. luciliae thermophila at high temperatures. Adenosine could be used by the 2 Crithidia as a purine source at 28 but not at 37 C.     

Extra Nutritional Requirements of Artificially Aposymbiotic Crithidia deanei*

SYNOPSIS. Chloramphenicol cured Crithidia deanei of its endosymbiote. The derived aposymbiotic strain had additional growth requirements: purin (as adenine), heme, arginine, histidine, isoleucine, leucine, phenylalanine, threonine, tryptophan, valine, pyridoxine, riboflavin, and pantothenate and liver infusion (replaceable by high nicotinamide).     

THE EFFECTS OF NITROGEN SUPPLY UPON THE VERTICILLIUM WILT OF ANTIRRHINUM

Isolates of Verticillium albo-atrum, V. dahliae and V. nigrescens grown on media adequately supplied with sodium nitrate induced wilt rather more rapidly in antirrhinum plants growing in soils with a normal and an excessive amount of nitrogen than in plants in nitrogen-deficient soil, though plants became diseased in all soils. Similarly treated isolates of V. nubilum and V. tricorpus induced a greater incidence of wilt in plants in soil supplied with heavy dressings of organic nitrogenous fertilizer than in plants in soil deficient in nitrogen, although V. tricorpus from a medium containing much sodium nitrate, in contrast to V. nubilum , was pathogenic to plants in such deficient soil. The ability of the nitrogen-starved isolates to penetrate the host plant was significantly diminished, and even when wound-inoculated into stems their effect upon the host was much reduced.