Parasites of Salmo trutta L. from the Tirino River. Part IV. Intermediate hosts of Cyathocephalus truncatus (Pallas, 1781) and Dentitruncus truttae Sinzar, 1955

During studies on helminth parasites of brown trout (Salmo trutta L.) from the river Tirino (L'Aquila - Italy), the intermediate hosts of Cyathocephalus truncatus (Pallas, 1781) and Dentitruncus truttae Sinzar, 1955 have been searched for. A total of 15,444 amphipoda belonging to the following 3 species: Echinogammarus roco Karman, 1973, Echinogammarus tibaldii Pinkster and Stock, 1970, and Gammarus italicus Goedmakers and Pinkster, 1977, have been dissected. E. roco, E. tibaldii and G. italicus were found infected with procercoid of Cyathocephalus truncatus (new hosts record and first procercoid record in Italy). E. roco, E. tibaldii and G. italicus were found infected with acanthella and cystacanth of Dentitruncus truttae (first record of intermediate hosts). Accordingly the ecology of the cestod C. truncatus and of the acanthocephalan D. truttae in their intermediate hosts has been studied considering principally the incidence and the seasonal occurence of the parasites.     

Calf development and mother-calf spatial relationships in Southern right whales

Changes in spatial relationships between mother and calf right whales (Eubalaena australis) from birth to the separation of yearling calves from their mothers were observed. During the first few weeks of a calf's life, mother and calf were within close proximity over 90% of the time, and mothers were responsible for maintenance of contact with their infants. Later calves strayed farther and initiated many more leaves and approaches than their quiescent mothers. The mothers still maintained contact with their infants. Just before migration away from the area, pair members resumed close proximity and leaves and approaches by both diminished. Yearling calves, returning to the area with their mothers after six months, stayed close to their mothers and few leaves and approaches by either pair member were recorded. The yearling calves were responsible for maintaining contact as the mothers left them more than approached them. This behaviour on the part of mothers probably contributed to weaning of yearlings and separation after a few weeks in the area.     

Theiler's virus infection induces a specific cytotoxic T lymphocyte response

Theiler's virus, a murine picornavirus, persists in the central nervous system of susceptible mouse strains and causes chronic inflammation and primary demyelination. One of the current hypotheses is that demyelination is, at least in part, mediated by virus-specific cytotoxic T lymphocytes (CTL). However, it is generally assumed that picornaviruses do not induce CTL. In point of fact, their existence has only been demonstrated for Coxsackievirus B-3. To determine whether Theiler's virus induces a CTL response, we generated a murine mastocytoma cell line stably transfected with the coding region of the genome of Theiler's virus strain DA. Using these cells as targets we showed that infected DBA/2 mice, a susceptible strain, produce cytotoxic T lymphocytes. The cytotoxic activity was Theiler's-virus specific. It was for the most part mediated by CD8+ T lymphocytes and H-2 restricted. This is the first demonstration that a specific CTL response is generated during Theiler's virus infection.     

The role of Acanthospermum hispidum in the phenology of Euschistus heros and of Nezara viridula

Laboratory, greenhouse, and field studies with Euschistus heros (F.) and Nezara viridula (L.) (Heteroptera: Pentatomidae) in northern Paraná, Brazil, demonstrated greater survival and longevity with E. heros than N. viridula when fed the weed Acanthospermum hispidum DC. (Compositae). E. heros was better adapted to A. hispidum than N. viridula but neither species reproduced on this plant. Stink bugs moved from soybean to A. hispidum mainly during mid-March to mid-April when soybean plants matured. The infestation reached 60 and 100% with a maximum of ca. 3 and 10 stink bugs/plant in 1988 and 1989, respectively. Surprisingly, E. heros and N. viridula, which are normally seed-feeders, strongly preferred the high moisture stems of A. hispidum. Both species demonstrated similar feeding frequencies. These results suggest that in northern Paraná, the common weed, A. hispidum functions as a temporary host providing water and nutrients to those two pentatomid pests of soybean. Finally, both species do not seem to recognize A. hispidum as an unsuitable or perhaps toxic plant.     

In vitro susceptibility of Erwinia amylovora (Burrill) Winslow et al. to geraniol and citronellol

The in vitro antimicrobial activity of geraniol and citronellol towards seven strains of Erwinia amylovora , the causal agent of 'fire blight'of Rosaceous plants, was assessed in tube cultures. All of the strains tested at 1 × 10⁵ cfu/ml were inhibited for 24 h by geraniol in the range 600–1500 mg/1, whereas its minimum bactericidal concentration was 800–1700 mg/1. Citronellol was less effective, being bactericidal for only two of seven strains. RIF-NY, isolated from apple orchards, was relatively resistant to geraniol; 1700 mg/1 of the chemical only reduced the growth of an inoculum of 1 × 10⁷ cfu/ml. In general, such terpenoids commenced exerting a bactericidal effect 6 h after addition to the suspensions, even if geraniol added at 1700 mg/1 to 1 × 10³ cfu/ml of five strains, commenced its bactericidal activity earlier than 6 h.     

Pregnancy modulates the expression of beta-N-acetylhexosaminidase in rat serum and tissues.

1. beta-N-Acetylhexosaminidases in maternal rat serum were separated by DEAE-cellulose chromatography and compared with those of adult rat serum. 2. In pregnant serum there is an increase of the isoenzymes which are entirely composed of beta-subunits (B and intermediate forms). 3. These alterations could be compared to those already described in human pregnancy. 4. The levels of beta-N-acetylhexosaminidase and the relative expression of alpha- and beta-subunits in normal and pregnant serum correlate with the above isoenzyme expression. 5. The increase of B and intermediate forms as well as the increase of specific activity during pregnancy was not peculiar to maternal serum but was also demonstrated in several foetal tissues and in maternal tissues, in which cases the beta-N-acetylhexosaminidase isoenzyme patterns closely resemble the foetal ones rather than those of the adult rat tissues. 6. These analogies strongly suggest that the expression of beta-subunit of beta-N-acetylhexosaminidase is regulated by hormones or other factors related to pregnancy.     

Metabolism of Guanine and Guanine Nucleotides in Primary Rat Neuronal Cultures

The metabolic fate of guanine and of guanine ribonucleotides (GuRNs) in cultured rat neurons was studied using labeled guanine. 8-Aminoguanosine (8-AGuo), an inhibitor of purine nucleoside phosphorylase, was used to clarify the pathways of GMP degradation, and mycophenolic acid, an inhibitor of IMP dehydrogenase, was used to assess the flux from IMP to GMP and, indirectly, the activity of the guanine nucleotide cycle (GMP----IMP----XMP----GMP). The main metabolic fate of guanine in the neurons was deamination to xanthine, but significant incorporation of guanine into GuRNs, at a rate of approximately 8.5-13.1% of that of the deamination, was also demonstrated. The turnover rate of GuRNs was fast (loss of 80% of the radioactivity of the prelabeled pool in 22 h), reflecting synthesis of nucleic acids (32.8% of the loss in radioactivity) and degradation to xanthine, guanine, hypoxanthine, guanosine, and inosine (49.3, 4.3, 4.1, 1.1, and 0.5% of the loss, respectively). Of the radioactivity in GuRNs, 7.9% was shifted to adenine nucleotides. The accumulation of label in xanthine indicates (in the absence of xanthine oxidase) that the main degradative pathway from GMP is that to xanthine through guanosine and guanine. The use of 8-AGuo confirmed this pathway but indicated the operation of an additional, relatively slower degradative pathway, that from GMP through IMP to inosine and hypoxanthine. Hypoxanthine was incorporated mainly into adenine nucleotide (91.5%), but a significant proportion (6%) was found in GuRNs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Biological characterization of Trichinella isolates from various host species and geographical regions.

Forty isolates of Trichinella collected from 5 continents were compared for 7 biological characters: newborn larvae produced per female worm cultured in vitro at the seventh, eighth, and ninth day postinfection, host muscle nurse cell development time, reproductive capacity index in rats and chickens, and resistance of muscle larvae to freezing. The isolates also were compared by analyses of an environmental character of the location from which they were isolated: the isotherms for January and July. By factorial analysis of correspondence of the biological and environmental data, the 40 isolates were grouped into 8 gene pools (T1-T8). The environmental temperature-related distribution was more evident for the sylvatic isolates (T2, T3, T5, T6, T7, T8), than for T1, which was isolated from domestic pigs, and for T4, a bird-adapted, nonencapsulating genetic type. The 8 biological groups correlated closely with the 8 gene pools previously identified on the basis of allozyme analysis. These results support the concept that the genus Trichinella is composed of at least 5 distinct gene pools or sibling species: Trichinella spiralis sensu stricto (T1), Trichinella nativa (T2), Trichinella sp. (T3), Trichinella pseudospiralis (T4), and Trichinella nelsoni (T7), and 3 other groups of uncertain taxonomic status (i.e., T5, T6, and T8).