Studies on the host specificity of the eyefluke, Diplostomum spathaceum, in brown and rainbow trout

Trout collected from the Hanningfield Trout Farm in Essex, England, were found to be infected with Diplostomum spathaceum. Yearling rainbow trout were blinded with heavy infections of eyefluke, whereas brown trout of the same age carried one-tenth the number of flukes and were clear eyed. Both species were reared under identical conditions, in parallel rearing channels which received water from a common source. Samples showed that young fish exhibited a similar differential in their infestations, and that rainbow trout did not appear to be age-resistant. Laboratory infections produced by exposure of fish to suspensions of cercariae and injection of cercariae into the body cavity reflected the field results, indicating that ecological factors were not involved. Recovery of cercariae from host tissues, and histological observations of similar numbers entering both hosts, indicated that cercariae were able to survive penetration. Excised eye preparations were equally susceptible to infection. Two cm fry of both species were shown to be highly susceptible. Migration in brown trout took 3 h longer than in rainbow trout of the same size, many cercariae being found in the heart during this time. Two mechanisms of insusceptibility were suggested: (1) a greater impenetrability of brown trout tissues; (2) a disorientation of migrating cercariae in brown trout.

Homologous viral interference in trout and Atlantic salmon cell cultures infected with infectious pancreatic necrosis virus

The occurrence of homologous interference in the replication of infectious pancreatic necrosis virus was demonstrated after successive passages of partially purified virus at high input multiplicities in trout and Atlantic salmon cell cultures. Pretreatment of cell cultures with interfering virus inhibited the replication of homologous standard infectious virus but not unrelated viruses. The ability of infectious pancreatic interfering virus to interfere with homologous virus was abolished with UV irradiation, immune serum, and freeze-thawing.

Enzymatic modifications of the protamines. II. Separation and characterization of phosphorylated species of protamines from trout testis

Substantial quantities of highly phosphorylated protamines were prepared from hormonally induced trout testes at the early protamine stage of development. Purified protamines from testes induced to mature by injection of salmon pituitary extracts were resolved into eight fractions on long carboxymethyl cellulose columns by eluting with a gradient of LiCl in the presence of 6 M urea; only two major fractions were found in protamine extracted from naturally maturing testes. Each fraction was not homogenous but consisted of a mixture of several related protamines. Analysis of radioactivity in in vivo32P-labeled protamine indicated that six of the eight fractions were phosphorylated. Amino acid analysis, phosphate determinations, and starch gel electrophoresis indicated that three of the phosphorylated peaks correspond to the mono-, di-, and triphosphorylated derivatives of the first fraction (three serines) of protamine, while the other three correspond to a similar series of the second fraction (four serines) of protamine. These protamines with differing levels of phosphorylation may be useful for in vitro studies of the interaction of phosphoprotamines with DNA or chromatin.

Nuclear proteins during development: incorporation of leucine into histones of rainbow trout during early development

Nuclear histones of embryos of rainbow trout (Salmo gairdnerii) were isolated after incubation of cell suspensions with [4,5-3H]leucine. The incorporation of leucine into nuclei at 10 °C was found to occur linearly for 4 h. At all stages examined from very early blastula to [Formula: see text] epiboly, a component identical in mobility to histone I was found when a sensitive staining technique was employed. The relative proportion of histone IIId is higher at early blastula, and decreased by mid-blastula to a level which remains constant relative to other components during the remainder of the stages examined. The major proportion of the leucine incorporated into histones is found at all stages in histones IIb1 and IIb2, but as development occurs, the relative proportion of incorporation into histone IV increases until at [Formula: see text] epiboly, it is almost equal to either histone IIb1 or IIb2.

Patterns of incorporation of (32P)orthophosphate and (3H)acetate into histones of rainbow trout during early development

Nuclear histones of embryos of rainbow trout (Salmo gairdnerii) were isolated after incubation of cell suspension with [32P]orthophosphate and sodium [3H]acetate. In all stages examined from early blastula to neurula, the major proportion of phosphate incorporated was located in histones IIb1 and I. The major histones into which acetate was incorporated were IIb2 and/or IIIm and I. Peaks of acetate and phosphate do not appear at the same positions on acrylamide gels of doubly labelled histones and thus acetylation and phosphorylation appear to be two different alternative or sequential processes. Tryptic digestion of IIb1 indicates that the main site of phosphate incorporation into IIb1 is similar to that found in trout testis, but it is possible that a difference exists since, after thermolysin digestion, the phosphopeptides obtained are not identical with those reported for trout testis IIb1.

Patterns of incorporation of (3H)leucine and (32P)orthophosphate into nonhistone proteins of rainbow trout during early development

In rainbow trout eggs developing at 10 °C, the relative amounts of nonhistone proteins of the embryo nuclei change during the course of cleavage; the relative amounts of at least two of the proteins seem to increase whereas four decrease during this period. [4,5-3H]leucine is incorporated into all components that stain visibly with Coomassie blue from mid-blastula on, and into approximately seven components at early blastula. [32P]orthophosphate is incorporated into three of the components of the nonhistone proteins, which also stain intensely with Coomassie blue. The results support a role for the nonhistone proteins in the control of differentiation and are in sharp contrast to the lack of change in the relative concentrations of the histones following the late blastula stage.