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Biomedical subjects

O Halkka

Publications and source records attributed to O Halkka.

At least 19 recordsLinked to original sources
PubMed1987

Alcohol-preferring (AA) and alcohol-avoiding (ANA) lines of rats after introgression of alien genes.

Outcrossing has been used as a method for introducing new genetic variability into the high-drinking AA and low-drinking ANA rat lines that had reached their selection limits and were suffering of poor fertility and decreased litter size. The response to the renewed selection for differential alcohol consumption, and the effect of outcrossing upon the components of productivity are reported.

Alcohol Drinking↗
PubMed1977

The effects of chronic ethanol consumption on goniomitosis in the rat.

Male rats, provided with dissimilar diets with regard to thiamine (deficient, normal and superfluous) received either water or alcohol (7-20%: w/v) as the only supply of liquid for 4-7 months. Mitotic acitivity was very low in the spermatogonia of many of the individuals especially those belonging to the alcohol groups. The frequency of cells with visible chromosomal defects was invariably quite low. It seems that combining abnormal thiamine supply with alcoholism does not lead to a drastic increase in the frequency of chromosomal aberrations.

Alcoholism↗
PubMed1977

Accumulation of gene products in the oocytes of the dragonfly Cordulia aenea. II. Induction of annulate lamellae within dense masses during diapause.

During the 3 years of nymphal development of the dragonfly Cordulia aenea, gene products slowly accumulate in the cytoplasm of the previtellogenic oocytes. Nuclear extrusions separate into nematosome and dense-mass components. The dense masses, RNP-containing globules of thightly packed fibrillar material, disperse throughout the oocyte cytoplasm. The last instar nymph experiences an obligatory diapause, after which oocyte development passes from mid to late previtellogenesis, and eventually to vitellogenesis proper in the adult. During diapause, annulate lamellae are induced within the dense masses. This process is continued during late previtellogenesis. The formation of annulate lamellae may be related to activation of some genetic message stored in the dense masses. The possibility of tubulin synthesis is discussed.

Animals↗
PubMed1976

Enzyme polymorphism in feral, outbred and inbred rats (Rattus norvegicus).

Polymorphism at 25 loci coding for liver enzymes was studied in two feral, three outbred and three inbred rat strains by starch gel electrophoresis. No variation was found at 14 loci, and a low degree of polymorphism was detected at three. Eight loci were polymorphic in more than one population. The average degree of heterozygosity per locus per individual feral rat was 0-07. The degrees of heterozygosity observed in the outbred and inbred strains were lower, from 0-006 to 0-012. Contrary to expectation, the inbred strains were neither monomorphic nor appreciably less heterozygous than the outbred ones. The heterozygosity of the inbred strains was primarily due to two polymorphic loci, G-3-pdh and alpha-Gpdh. The reason for this polymorphism is probably the superior homeostasis of the heterozygotes.

Animals↗
PubMed1976

Goniomitosis in rats affected by mycoplasma or macrolides.

Infection with Mycoplasm pulmonis caused a slight increase in the incidence of chromosome breaks in goniomitotic cells of the rat testis. No differences existed between healthy and infected rats in the frequency of mitotic divisions, measured as the number of metaphases per slide. The macrolide antibiotics erythromycin and tylosin are widely used as antimycoplasmal drugs. Erythromycin was given to healthy rats intramuscularly at a concentration of 20 mg/kg, and tylosin perorally in the drinking water at a concentration of 0.1%, both for 10 days. Neither drug induced an increase in the incidence of chromosome breaks in the spermatogonia. But both these macrolides caused a definite reduction in the therapy of cell division. With erythromycin, this effect had disappeared 18 days after the end of treatment.

Animals↗
PubMed1976

Goniomitosis in rats subjected to ethanol.

Prolonged compulsory consumption of ethyl alcohol does not increase the incidence of chromosomal abnormalities in the spermatogonial cells of the rat. This was the result of an experiment in which rats given a nutritionally adequate diet received 10% (v/v) ethyl alcohol as their only supply of liquid for 70 days.

Animals↗
PubMed1975

Clines in the colour polymorphism of Philaenus spumarius in Eastern Central Europe.

Populations of Philaemus spumarius (Homoptera) have been investigated in the Baltic States of the USSR, in Czechoslovakia and in Hungary. Colour morph frequencies in these highly polymorphic populations are compared with those reported earlier from northern Italy. Gradual changes in allele frequencies (clines) transect the study area, which lies in the most central part of the range of Philaenus in Europe. From north to south the allele pM increases, but pO decreases, in frequency. In their distribution, some of the other alleles also showed regional gradients. The possibility that visual selection varies regionally is dismissed on indirect grounds. Gradients in climatic severity, or in other environmental variables changing concomitantly with climate, are regarded as the primary cause of the observed clines and other differences between regions.

Alleles↗
PubMed1975

Accumulation of gene products in the oocytes of the dragonfly Crodulia Aenea L.. I. The nematosomes.

The chromosomes of the active previtellogenic oocytes of the dragonfly Cordulia aenea L. extrude into the cytoplasm a substance, which is subsequently found there in the form of granulofibrillar masses. These nuclear extrusions evolve ultrastructurally into two components, nematosomes and dense masses. The nematosomes are later found transitorily adjacent to the mitochondria and undergo transformations that are synchronized with changes in oocyte activity. It is suggested that the nematosomes are storage structures for long-lived informational RNA and that they man be widely distributed in various types of cells containing such RNA.

Animals↗
PubMed1968

RNA and protein in nucleolar structures of dragonfly oocytes.

Dragonfly and damselfly oocytes regularly contain two nucleolus like bodies of different sizes, a primary nucleolus and a secondary nucleolus. The primary nucleolus stains more deeply with RNA stains than with an arginine stain; the seconidary nuicleolus stains conzversely. The primary nulcleolus incorporates uridine under all conditions tested; the secondary, only after precautions have been taken to preserve soluble RNA. Both inicorporate lysine.

Animals↗