Effects of sea trout stocking on the population genetics of landlocked brown trout, Salmo trutta L., in the Conwy River system, North Wales, U.K.

The effect of the introduction of fry of anadromous sea trout, Salmo trutta L., on the genetic integrity of landlocked brown trout populations was evaluated. Samples were taken from six brown trout populations from streams above impassable waterfalls in the Conwy river system (North Wales, U.K.) in 1989 and 1990. Three of these streams had no known stocking history and three had been stocked with sea trout fry from the lower Conwy system over the last few years. Representatives of these sea trout were collected from two streams in the lower Conwy system and from a hatchery. Allele frequencies at 13 loci, six of which were polymorphic, were determined by starch gel electrophoresis.
The stocked populations were intermediate in their allele frequencies between unstocked brown trout and sea trout samples. A principal component analysis suggested significant numbers of hybrids in all of the stocked streams. This shows that some of the introduced sea trout did not migrate down the falls to the sea, but stayed in fresh water and hybridized with the local population. The significance of this finding for the conservation of the genetic resource of brown trout stocks is discussed.     

Characteristics of [3H]GBR 12935 Binding in the Human and Rat Frontal Cortex

Binding characteristics of the selective dopamine uptake inhibitor [3H]GBR 12935 have been described for the striatum but not for the frontal cortex. We have developed assay conditions for quantifying [3H]GBR 12935 binding in the frontal cortex. In both the rat and human frontal cortex, the assay required four times more tissue (8 mg/ml) than in the striatum (2 mg/ml). [3H]GBR 12935 binding in the frontal is complex, as it involves multiple binding sites. The high-affinity binding site is sodium dependent and is inhibited by sodium. In human but not in rat frontal cortex, addition of K+ reversed the sodium inhibition. The pharmacological profile of the high-affinity [3H]GBR 12935 binding site is consistent with that of the dopamine transporter, because drugs with the most selective dopamine reuptake blocking activities are the most potent displacers of [3H]GBR 12935 binding. There is a positive correlation between the rat and human inhibitory constants, a finding indicating that there are similar pharmacological profiles across at least these two species. Rats with a 6-hydroxydopamine lesion had a 47% decrease in number of [3H]GBR 12935 binding sites, a result indicating that at least a portion of these sites had been on presynaptic dopamine terminals.     

Human herpesvirus 7: antigenic properties and prevalence in children and adults.

The recent isolation of human herpesvirus 7 (HHV-7) from activated CD4+ T lymphocytes of a healthy individual raises questions regarding the prevalence of this virus in humans and its immunological relationship to previously characterized human herpesviruses. We report that HHV-7 is a ubiquitous virus which is immunologically distinct from the highly prevalent T-lymphotropic HHV-6. Thus, (i) only two of six monoclonal antibodies to HHV-6 cross-reacted with HHV-7-infected cells, (ii) Western immunoblot analyses of viral proteins revealed different patterns for HHV-6- and HHV-7-infected cells, (iii) tests of sequential serum samples from children revealed seroconversion to HHV-6 without concomitant seroconversion to HHV-7, and (iv) in some instances HHV-7 infection occurred in the presence of high titers of HHV-6 antibodies, suggesting the lack of apparent protection of children seropositive for HHV-6 against subsequent infection with HHV-7. On the basis of the analyses of sera from children and adults it can be concluded that HHV-7 is a prevalent human herpesvirus which, like other human herpesviruses, infects during childhood. The age of infection appears to be somewhat later than the very early age documented for HHV-6.     

Host-constrained epidemiology of the fish tapeworm Ligula intestinalis (L.)

Investigations into the biology of the roach, Rutilus rutilus (L.), and Ligula intestinalis (L.) populations at Slapton Ley, Devon were carried out between October 1982 and December 1984, and additional data collected from the lake since 1977 have been re-analysed. The Ligula population exhibited some unusual features: a limited specificity, a persistently low abundance and a scarcity of multiple infections. The population dynamics of the roach were also unusual in that the individual growth rate was one of the fastest in Britain, the survival was very poor and the year classes tended to alternate in strength. Whether the unusual epidemiology of Ligula could be explained by the unusual population dynamics of the roach is investigated. The transmission period of Ligula to the roach was limited to their first few months of life, probably due to a limited period of feeding on copepods by the fry. This narrow transmission window was almost certainly the major factor that has prevented the abundance of Ligula plerocercoids attaining high levels in the fry or of increasing in subsequent years, and has resulted in their abundance being determined entirely by transmission events to the fry. The limited transmission period has also caused the life-cycles of the roach and Ligula populations to become synchronized. At other localities, the abundance of Ligula is typically high, and can have a significant effect on the mortality of the host population, but, with the low abundance at Slapton, Ligula-induced roach mortality was insignificant. The rapid growth of the roach fry was the most likely explanation for the limited period of feeding on copepods, and the large size, short life-span and low abundance of the roach probably also constrained the build-up of the Ligula population in the lake. The random frequency distribution and scarcity of multiple infections was not considered unusual in view of the very low plerocercoid abundance. The very low abundance of Ligula, the separation of the spawning of roach and rudd in time and space, and the scarcity of rudd may account for the absence of infection in this species. It was concluded that the Ligula population in Slapton Ley was being constrained by the atypical population dynamics of the roach, and not vice versa as theory predicts.     

Low-dose apomorphine reduces serum homovanillic acid concentrations in schizophrenic patients

This study was carried out to evaluate the postulated dopaminergic autoreceptor regulatory effect in man of low-dose apomorphine. Behavior and serum homovanillic acid concentrations following low-dose apomorphine were investigated. Five medicated chronic schizophrenic patients had serum homovanillic acid concentrations measured by mass fragmentography before and after 0.005 mg/kg of apomorphine or saline placebo. Results demonstrate significant reductions in serum homovanillic acid concentrations in all five subjects following apomorphine as compared with placebo. These findings present direct evidence of a specific dopamine autoreceptor effect of low-dose apomorphine in schizophrenic patients.     

Proteins of Norwalk virus.

The proteins of the Norwalk virus were studied by polyacrylamide gel electrophoresis. Highly purified specifically immunoprecipitated virions appeared to contain a single primary structural protein with a molecular weight of 59,000. In addition, a soluble Norwalk viral protein with a molecular weight of 30,000 was identified in fecal specimens containing Norwalk virus. The protein structure of the virion is similar to that of the Calciviridae family.     

Further biochemical data on Qa-2

The Qa-2 differentiation alloantigen is coded by a gene situated between the D and Tla loci of the murine major histocompatibility complex (H-2). Qa-2-bearing protein was isolated by immunoprecipitation and found to be composed of subunits of 40 000 and 12 000 daltons by SDS polyacrylamide gel electrophoresis (PAGE). The 12 000 dalton material was identified as 2-microglobulin (2M) by its molecular weight (SDS PAGE), charge (isoelectric focusing), antigenicity (reactivity with xenogenic anti- 2M), and genetics. The 40 000 dalton mol. wt. of Qa-2 heavy chain is 5 000 daltons less than that of D and K molecules (45 000 daltons). The quantity of Qa-2 isolated by immunoprecipitation was found to vary in a strain-specific fashion and as much as a 15-fold difference was observed.Abbreviations used in this paper B6 C57BL/6 strain mice - B10 C57BL/10 mice - 2M beta 2-microglobulin - IEF isoelectric focusing - K 1000 daltons - MHC major histocompatibility complex - PAGE polyacrylamide gel electrophoresis - SDS sodium dodecyl sulfate - TL thymusleukemia antigen     

Hog barn dust extract stimulates IL-8 and IL-6 release in human bronchial epithelial cells via PKC activation.

Hog barn workers have an increased incidence of respiratory tract symptoms and demonstrate an increase in lung inflammatory mediators, including interleukin (IL)-8 and IL-6. Utilizing direct kinase assays for protein kinase C (PKC) activation, we demonstrated that dust from hog confinement facilities, or hog dust extract (HDE), augments PKC activity of human airway epithelial cells in vitro. A 5% dilution of HDE typically stimulates an approximately twofold increase in human bronchial epithelial cell (HBEC) PKC activity compared with control medium-treated cells. This increase in PKC is observed with 15 min of HDE treatment, and kinase activity reaches peak activity by 1-2 h of HDE treatment before returning to baseline PKC levels between 6 and 24 h. The classic PKC inhibitor, calphostin C, blocks HDE-stimulated PKC activity and associated IL-8 and IL-6 release. Desensitization to HDE stimulation of PKC activation does not appear to occur because subsequent exposures to HDE after an initial exposure result in further augmentation of PKC. Detoxification of HDE with polymyxin B to remove endotoxin did not change PKC activation or IL-8 release, suggesting that endotoxin is not solely responsible for HDE augmentation of PKC. These data support the hypothesis that HDE exposure augments HBEC IL-8 and IL-6 release via a PKC-dependent pathway.     

REPRODUCTIVE BIOLOGY OF THE YELLOW-FRINGED ORCHID,PLATANTHERA CILIARIS

Platanthera ciliaris is a butterfly-pollinated, terrestrial orchid with a loose terminal raceme of 10–50 orange flowers, characterized by a long nectariferous spur. In the southeastern United States, P. ciliaris occurs in the Appalachian Mountains and Coastal Plain physiographic provinces, but rarely in the intervening Piedmont. Of 153 plants that flowered in a Mountain population in 1983, 54 (35.2%) flowered again in 1984; in a Coastal Plain population, only 51 of 306 (16.7%) flowered in both years. Experimental pollinations showed that P. ciliaris is self-compatible but not autogamous. Nectar volume increased over the 6- to 7-day life span of a flower, reaching a maximum of 4 μl and 1.0 mg of sugar (Mountains) or 6 μl and 1.2 mg of sugar (Coastal Plain). Nectar concentrations were relatively constant in flowers of all ages and averaged 23% in the Mountains and 19% in the Coastal Plain. Diurnal patterns of nectar secretion were not well-defined, but most nectar appeared to be produced overnight. In the Mountains Papilio troilus (spicebush swallowtail) was the most frequent and effective pollinator, whereas in the Coastal Plain P. palamedes (palamedes swallowtail) was the predominant pollinator. These large butterflies were most active in the late morning (0930–1030) and early afternoon (1230–1400). Levels of pollinator service, as assessed by rates of removal and insertion of pollinia, were higher in the Mountains (0.81, 0.86) than in the Coastal Plain (0.63, 0.67). These values were reflected in higher levels of fruit-set in Mountain (83.9% in 1983, 86.5% in 1984) than in Coastal Plain (63.8, 65.5%) populations. Combining these observations with the fact that hand pollination increased fruit-set of Coastal Plain flowers 6.5–13.5% above open-pollinated controls, it appears that fruit-set in P. ciliaris is pollen-limited.     

Inhibition Enzyme-Linked Immunosorbent Assay for Detection of Pseudomonas fluorescens Proteases in Ultrahigh-Temperature-Treated Milk

An inhibition enzyme-linked immunosorbent assay was developed to detect low levels of the proteases extracted from four strains of Pseudomonas fluorescens. The assay detected between 0.24 and 7.8 ng of protease per ml of ultrahigh-temperature-treated milk and could be completed within 6 h. It could be used as a framework for a test system for quantifying spoilage proteases in dairy products.