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PubMedDate not supplied

[Temperature-sensitive mutants of Japanese encephalitis virus, isolated from chronically infected cultures of suckling mouse brain cells].

Reproduction of Japanese encephalitis virus isolated at various passage levels from chronically infected GMS-1-K33 cell cultures was maximum in chick embryo fibroblast cultures at a temperature of 28 degrees C. A temperature of 42 degrees C was found to be nonpermissive for the majority of variants and restrictive for the 20th passage virus. Some decline in titers was also observed at 37 degrees C. The ts mutants derived from the population of the persisting virus had lower pathogenicity for laboratory animals, were sensitive to RNA-ase and resistant to 4 M urea. The data obtained by us and other authors suggest that appearance and selection of ts mutants in persistent infection in cell cultures in a regular phenomenon playing a significant role both in establishment and maintenance of persistently infected systems.

Animals↗
PubMed2001

Wolbachia-induced incompatibility precedes other hybrid incompatibilities in Nasonia.

Wolbachia are cytoplasmically inherited bacteria that cause a number of reproductive alterations in insects, including cytoplasmic incompatibility, an incompatibility between sperm and egg that results in loss of sperm chromosomes following fertilization. Wolbachia are estimated to infect 15-20% of all insect species, and also are common in arachnids, isopods and nematodes. Therefore, Wolbachia-induced cytoplasmic incompatibility could be an important factor promoting rapid speciation in invertebrates, although this contention is controversial. Here we show that high levels of bidirectional cytoplasmic incompatibility between two closely related species of insects (the parasitic wasps Nasonia giraulti and Nasonia longicornis) preceded the evolution of other postmating reproductive barriers. The presence of Wolbachia severely reduces the frequency of hybrid offspring in interspecies crosses. However, antibiotic curing of the insects results in production of hybrids. Furthermore, F1 and F2 hybrids are completely viable and fertile, indicating the absence of F1 and F2 hybrid breakdown. Partial interspecific sexual isolation occurs, yet it is asymmetric and incomplete. Our results indicate that Wolbachia-induced reproductive isolation occurred in the early stages of speciation in this system, before the evolution of other postmating isolating mechanisms (for example, hybrid inviability and hybrid sterility).

Animals↗
PubMed1992

Isolation of pathogenic strains of Haemophilus somnus from the female bovine reproductive tract.

The prevalence of Haemophilus somnus in the genital tract of slaughtered and live cows in southern Ontario was investigated. The vagina and uterus of slaughtered cows were swabbed separately. Live cows were examined and sampled in two field surveys: Centre A and Centre B. In the former, aspirated mucus secretions and in the latter, specimens obtained by guarded swabbing were examined bacteriologically. Haemophilus somnus was isolated from 28 genital tracts of 461 slaughtered (6.1%), and seven of 199 live (3.5%) cows during the centre B survey. The isolates were recovered from both normal and diseased reproductive tracts. Fourteen strains isolated from genital organs were examined for pathogenicity in vivo to test the occurrence of pathogenic isolates. In the initial stage of the in vivo study on pathogenicity, each of the fourteen isolates was examined on one calf using an intracisternal inoculation. Subsequently, one pathogenic and one nonpathogenic strain were inoculated into five calves each to statistically confirm their pathogenic potential. Of 14 genital isolates of H. somnus examined in an intracisternal calf assay, six (43%) caused a fatal peracute neurological disease, while eight were nonpathogenic. A comparative pathological study of pathogenic and nonpathogenic isolates showed that the former caused a severe fatal suppurative meningoencephalitis whereas the latter caused no lesions whatsoever or a mild leukocytic leptomeningitis. The salient data obtained in this study indicate that there are pathogenic strains of H. somnus in the genital tract of apparently normal cows as well as of those with inflammatory disease.

Abattoirs↗
PubMed1993

Effect of intravenous inoculation of avian influenza virus on reproduction and growth in mallard ducks.

An avian influenza virus isolate, A/Mallard/Ohio/184/86 (H5N1), was evaluated for its effects on reproduction in isolation-reared adult mallard ducks (Anas platyrhynchos) and growth rate in juvenile mallards after intravenous inoculation. There was a significant decrease in egg production in the experimental group during the first week after inoculation, but it returned to the normal production level during the second week. No effect was seen on egg weight, shape, or fertility. Ducklings receiving this influenza virus isolate did not differ from controls in their rate of growth.

Animals↗
PubMed1994

Characterisation of the S-adenosylmethionine decarboxylase (SAMDC) gene of potato.

S-adenosylmethionine decarboxylase (SAMDC) is involved in the biosynthesis of the polyamines, spermidine and spermine. Recently, we reported the isolation of a putative cDNA clone of the SAMDC clone of potato (Plant Mol Biol 20; 641-651). In order to confirm that the potato genes does encode SAMDC, a complementation experiment with a yeast strain that possesses a null mutation in the SAMDC gene was performed. The yeast strain contains a deletion-insertion mutation in the SAMDC gene and has an absolute requirement for the addition of exogenous spermidine for growth. When the full-length potato cDNA was expressed in the mutant yeast strain there was no longer a requirement for exogenous spermidine. Immunoblotting experiments suggest that the potato SAMDC gene product has an apparent molecular mass of 39 kDa. Expression of the SAMDC gene was high in the young and actively dividing tissues and low in the mature and non-dividing tissues of both vegetative and reproductive organs. Additionally, isolation and characterisation of the corresponding genomic clone is reported. The gene has one intron in its 5'-untranslated sequence but otherwise the transcribed portion is identical to the cDNA clone.

Adenosylmethionine Decarboxylase↗
PubMed1993

Evidence that primer pheromones do not cause social suppression of reproduction in male and female naked mole-rats (Heterocephalus glaber).

The role of chemical cues in mediating the reproductive suppression of nonbreeding males and females in colonies of naked mole-rats (Heterocephalus glaber) was examined by comparing reproductive activation in isolated nonbreeders with that of isolated nonbreeders maintained in olfactory and gustatory contact with their parent colony. Animals were either removed from their colony and paired directly with a member of the opposite sex from the same colony, or were removed, housed singly for 40 days, and then paired with a member of the opposite sex from the same parent colony that had also been housed singly for 40 days. Approximately half of these separated animals received a daily transfer of soiled bedding and litter from their parent colony. In females, there was no significant difference between the control and bedding transfer group, in the time taken from separation to the first sustained increase of urinary progesterone above 2 ng mg-1 Cr indicative of the luteal phase of an ovarian cycle (7.8 +/- 2.6 versus 9.4 +/- 2.0 days, respectively). In both control and bedding transfer groups, singly-housed females commenced ovarian cyclicity, revealing that the presence of a male was not required for reproductive activation and ovulation. In males, concentrations of both urinary testosterone and plasma LH increased after separation from their parent colonies in both control and bedding transfer groups, to reach values equivalent to those of breeding males.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Isolation of Mycoplasma californicum from an outbreak of bovine mastitis and the experimental reproduction of the disease.

A mycoplasma-like organism was isolated from five cows with chronic incurable mastitis from one dairy herd. This organism was shown to be Mycoplasma californicum and was used to infect three cows by intramammary inoculation. The challenge organism was reisolated from all the infected quarters and the ensuing inflammatory response produced a chronic mastitis with a permanent drop in milk yield. Antibiotic treatment in one animal was unsuccessful.

Animals↗
PubMed1998

Infectious transcripts from cloned genome-length cDNA of porcine reproductive and respiratory syndrome virus.

The 5'-terminal end of the genomic RNA of the Lelystad virus isolate (LV) of porcine reproductive and respiratory syndrome virus was determined. To construct full-length cDNA clones, the 5'-terminal sequence was ligated to cDNA clones covering the complete genome of LV. When RNA that was transcribed in vitro from these full-length cDNA clones was transfected into BHK-21 cells, infectious LV was produced and secreted. The virus was rescued by passage to porcine alveolar lung macrophages or CL2621 cells. When infectious transcripts were transfected to porcine alveolar lung macrophages or CL2621 cells, no infectious virus was produced due to the poor transfection efficiency of these cells. The growth properties of the viruses produced by BHK-21 cells transfected with infectious transcripts of LV cDNA resembled the growth properties of the parental virus from which the cDNA was derived. Two nucleotide changes leading to a unique PacI restriction site directly downstream of the ORF7 gene were introduced in the genome-length cDNA clone. The virus recovered from this mutated cDNA clone retained the PacI site, which confirmed the de novo generation of infectious LV from cloned cDNA. These results indicate that the infectious clone of LV enables us to mutagenize the viral genome at specific sites and that it will therefore be useful for detailed molecular characterization of the virus, as well as for the development of a safe and effective live vaccine for use in pigs.

Animals↗
PubMed1998

Selective potentiation of gynecologic cancer cell growth in vitro by electromagnetic fields.

OBJECTIVE: Epidemiological data suggest that exposure to electromagnetic fields (EMF) may increase the risk of various cancers. We evaluated EMF effects on the in vitro growth response of human cell lines isolated from various reproductive tract tissues. We also assessed the effects of EMF on cisplatin- or paclitaxel-induced cytotoxicity. METHODS: Endometrial, ovarian, and prostate cancer cell lines as well as immortalized endometrial stromal cells and immortalized ovarian epithelial cells were exposed continually to EMF. Proliferation was assessed by the metabolic activity assay, MTT, direct cell counting, and anchorage-independent colony formation in soft agar. Cytotoxicity induced by cisplatin or paclitaxel was assessed using the MTT assay. RESULTS: Continuous exposure to EMF at field strengths of 2 G enhanced proliferation of two human prostate and three endometrial, but only one ovarian, cancer cell lines. EMF enhanced metabolic activity of cancer cells within 96 h and increased absolute cell number (anchorage-dependent proliferation) and colony-forming efficiency (anchorage-independent proliferation) over sham-treated controls. EMF had no effect on cytotoxicity induced by the chemotherapeutic agents Taxol or cisplatin. CONCLUSIONS: Continuous exposure to EMF can enhance growth rates of transformed cells for some human epithelial cancers. Cancer cells from the steroid sex hormone regulated tissues of endometrium and prostate appeared to be more responsive to EMF than cells from ovarian cancers.

Cell Division↗
PubMed1977

Behavioral differences among isogenic strains of Drosophila mercatorum.

Mating propensity in eight all-female laboratory lines was measured. The lines are completely isogenic, but each has a different past history. In all cases, mating propensity was significantly lower than in the bisexual controls; in some cases, mating speed was less by a factor of 10. Three of the four lines deriving from the same wild strain are not only different from the parent strain but also different from each other. A highly significant difference exists between two strains recently obtained by selection for parthenogenesis from the same natural population. One strain appears to produce a substance which reduces mating propensity of control females if females from the two strains are reared together in the same vial. As none of the strains was behaviorally selected prior to testing, these behaviors appear to be incidental accompaniments of the very powerful isogenizing effect of the genetic system in these parthenogenetic strains. Indeed, the data show that partial isolation from sexual reproduction can arise wholly by chance. This may have some relevance to theories of species origin which are accompanied by a strong initial founder effect.

Animals↗
PubMed2006

Polar organizers and girdling bands of microtubules are associated with gamma-tubulin and act in establishment of meiotic quadripolarity in the hepatic Aneura pinguis (Bryophyta).

Meiosis in Aneura pinguis is preceded by extensive cytoplasmic preparation for quadripartitioning of the diploid sporocyte into a tetrad of haploid spores. In early prophase the four future spore domains are defined by lobing of the cytoplasm and development of a quadripolar prophase spindle focused at polar organizers (POs) centered in the lobes. Cells entering the reproductive phase become isolated and, instead of hooplike cortical microtubules, have endoplasmic microtubule systems centered on POs. These archesporial cells proliferate by mitosis before entering meiosis. In prophase of each mitosis, POs containing a distinct concentration of gamma-tubulin appear de novo at tips of nuclei and initiate the bipolar spindle. Cells entering meiosis become transformed into quadrilobed sporocytes with four POs, one in each lobe. This transition is a complex process encompassing assembly of two opposite POs which subsequently disperse into intersecting bands of microtubules that form around the central nucleus. The girdling bands define the future planes of cytokinesis and the cytoplasm protrudes through the restrictive bands becoming quadrilobed. Two large POs reappear in opposite cleavage furrows. Each divides and the resulting POs migrate into the tetrahedral lobes of cytoplasm. Cones of microtubules emanating from the four POs interact to form a quadripolar microtubule system (QMS) that surrounds the nucleus in meiotic prophase. The QMS is subsequently transformed into a functionally bipolar metaphase spindle by migration of poles in pairs to opposite cleavage furrows. These findings contribute to knowledge of microtubule organization and the role of microtubules in spatial regulation of cytokinesis in plants.

Bryophyta↗
PubMed2005

Molecular cloning and tissue distribution of SF-1-related orphan receptors during sexual maturation in female goldfish.

The steroidogenic factor (SF)-1 gene is one of a number of orphan nuclear receptors, which is a key transcriptional regulator in vertebrate reproduction. We have isolated the SF-1 homologue cDNA from the goldfish pituitary and designed primers for SF-1 on the basis of the highly conserved regions of various known SF-1 superfamily genes. SF-1 cDNA contained 1,948 nucleotides including an open reading frame predicted to encode a protein of 503 amino acids. The distribution pattern of SF-1 in a variety of tissues during sexual maturation in female goldfish was also examined by RT-PCR. Significant variations in the relative expression of SF-1 were observed in different tissues in immature and mature female goldfish. SF-1 transcript in pituitary was significantly higher than other tissues tested in immature and mature female goldfish. Lower expression of SF-1 was observed in the liver but was not detected in brain and ovary of the immature female goldfish. Presence of SF-1 was the predominant expression in the pituitary and brain of mature female goldfish. Also, in the mature female goldfish, a weak transcript was detected in liver and ovary. Interestingly, RT-PCR analysis revealed that the expression of SF-1 became higher in the brain and weaker in the liver in maturing female goldfish. Thus, SF-1 may be regulated in goldfish brain and/or liver. Thus is also tissue-specific distribution of SF-1 during sexual maturation in female goldfish.

Animals↗
PubMed1996

Seasonal changes in urinary odors and in responses to them by blind subterranean mole rats.

Breeding and nonbreeding season male and female mole rats from two chromosomal species of the Spalax ehrenbergi superspecies were tested in a tunnel T-maze to assess their responses to urine collected from breeding- and nonbreeding season male and female conspecific and heterospecific donors. The results indicate that S. ehrenbergi mole rat urine contains species-, sex-, and season-specific chemosensory cues and that male and female mole rats change their responses to these chemosensory cue depending upon the season. During the nonbreeding season, mole rats avoid conspecific and heterospecific urine of both sexes. In contrast, during the breeding season, mole rats do not avoid conspecific urine and males do not avoid heterospecific urine. These changes in responses to the chemosensory cues in urine are adaptive to their seasonal life underground because they could help the animals avoid aggressive encounters during the nonbreeding season and facilitate their approaching potential mates and competitors during the breeding season. The results suggest that chemical communication could play a role in social encounters, reproduction, and species isolation in the S. ehrenbergi superspecies.

Animals↗
PubMed1987

In vitro replication potential of serially passaged mammary parenchyma from mice with different reproductive histories.

Growth properties of multicellular units (organoids) of mouse mammary parenchyma have been analyzed. These intact units grew differently in collagen-matrix cultures than did dispersed cells prepared from them. The latter actively migrated in the collagen matrix and reorganized themselves into multicellular structures before producing three-dimensional protuberances in gel. Terminal unit (end-bud/alveoli)-enriched fractions grew more extensively than did ducts, as predicted from growth patterns in vivo. To assess the growth potential and the relationships between replication history in vivo and replication potential in vitro in mammary parenchyma, intact terminal units from mammary glands of mice of different ages and with different reproductive histories were isolated and their growth characteristics compared. Terminal-unit organoids were cultured in collagen gel matrix and passaged weekly for up to 5 weeks. Morphology, growth rates, and growth fractions were compared among organoids from young virgin, old virgin, monoparous, and multiparous mice. Morphologies observed in various passages of organoids from the groups of mice were similar. Organoids from old virgin and multiparous mice declined in growth rate for four passages and then growth rate increased again during the fifth passage. (However, fifth-passage organoids failed to form tumors if implanted in syngeneic mice in vivo.) Growth of organoids from either old or young virgin mice was less at any given passage than tissue from multiparous mice of similar age. Growth fractions of organoids from old parous mice were the same as those from old virgin mice but reached the same maximum fraction faster. Later passage organoids from the different mouse groups responded morphologically to the hormone combination of estrogen, progesterone, prolactin, and cortisone but not respond to cholera toxin. These results suggest that an animal's hormonal history (altered profoundly by pregnancy and lactation) may be as important as chronological age in determining subsequent growth potentials of mammary epithelium.

Aging↗
PubMed1993

Cocaine attenuates puberty acceleration in female house mice.

The onset of puberty in female house mice is advanced by exposure to a male urinary pheromone. This study tested whether cocaine could modify the juvenile female mouse's response to this pheromone. Puberty acceleration, as measured by uterine weight change, is inhibited by daily SC administration of 30 or 40 mg/kg body weight cocaine HCl between 20 and 26 days of age. Two daily injections of 20 mg/kg cocaine reduced both uterine development and body weight gain. Thus, cocaine may reduce an animals' reproductive fitness by isolating it from its social environment. At higher doses, cocaine can delay body growth, as well as the onset of puberty.

Analysis of Variance↗
PubMed2005

Identification of a novel male reproduction-related gene and its regulated expression patterns in the prawn, Macrobrachium rosenbergii.

To identify male-specific genes that could be involved in male development, we screened a subtracted male reproductive tract library and isolated a novel gene named Mar-Mrr (M. rosenbergii male reproduction-related gene). The Mar-Mrr cDNA sequence consists of 683 nucleotides with a 333 nucleotide open reading frame, encoding putative 110 amino acids (11.7473 kDa) precursor protein and a signal peptide consisting of 24 amino acids. Significant developmentally dependent accumulation of the mRNA was observed in the male reproductive tract, specifically in epithelial cells of vas deferens and terminal ampullae.

Amino Acid Sequence↗
PubMed2004

DNA vaccination of pigs with open reading frame 1-7 of PRRS virus.

We cloned all open reading frames of a Danish isolate of porcine reproductive and respiratory syndrome (PRRS) virus in DNA vaccination vectors. Pigs were vaccinated using a gene gun with each single construct (ORF1, ORF2, ORF3, ORF4, ORF5, ORF6, or ORF7) or combinations thereof. Vaccination with ORF7 consistently induced antibodies after three vaccinations, while antibodies were only sporadically detected in the remaining groups. After six vaccinations, all pigs were inoculated with PRRS virus and the post-inoculation antibody response was studied. Pigs vaccinated with ORF1 or ORF4 were primed for antibody response against NSP2 or GP4, respectively. Neutralising antibodies were detected in all pigs, with ORF5 vaccinated pigs showing the highest titres.

Animals↗
PubMed2001

The susceptibility of grayling (Thymallus thymallus) to experimental infections with the monogenean Gyrodactylus salaris.

The pathogenic monogenean Gyrodactylus salaris infecting Atlantic salmon (Salmo salar) is found to attach and reproduce under laboratory conditions on several species in the subfamily Salmoninae other than the Atlantic salmon. The gyrodactylid species Gyrodactylus thymalli infecting grayling (Thymallus thymallus) in another subfamily, Thymallinae, is previously said to be very similar to G. salaris based on morphometry and genetical analysis which prompted the present laboratory experiments to test the susceptibility and resistance of grayling to G. salaris. All 0+ and 1+ grayling became infected with G. salaris during the experimental infection procedure. However, both innate resistant and susceptible grayling were found. In susceptible individually isolated fish, parasite reproduction lasted for more than 35 days. Parasite reproduction also occurred among grouped grayling as judged from the duration of infection of more than 50 days. However, grayling susceptibility as judged from G. salaris reproduction, was very limited. Hence, the results indicate significant biological differences between the function of Atlantic salmon and grayling as host for G. salaris. The grayling is interpreted as unable to sustain G. salaris in nature which implies that G. thymalli is not conspecific with G. salaris. However, G. salaris dispersal by grayling cannot be excluded.

Animals↗