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Biomedical subjects

J Lokki

Publications and source records attributed to J Lokki.

13 recordsLinked to original sources
PubMed1979

Polyploidy in insect evolution.

Of all living organisms insects are the group with the highest number of existing species. It is, of course, true that a fraction of the total number of insects has been cytologically studied. Polyploid forms are rare exceptions among them. Polyploidy in insects is always associated with the parthenogenetic mode of reproduction. The cytologically verified cases are described. As for the geographic distribution of polyploid insects, they have successfully colonized vast land areas. Their distributions are, in general, northern and montane. The polyploid races are in general far more widespread than their diploid bisexual ancestors. The possible models of origin of polyploid insects are covered as well as data on their gaenetic variability. There are apparent environmental correlations in the distribution of certain forms. Most polyploid insects have life cycles extending over two (or more) years. They are also in general flightless forms. Hypotheses on the relation between heterozygosity in polyploids as well as the consequences of mutations in polyploid lineages are also presented.

Animals↗
PubMed1979

Theoretical considerations on HLA-associated illness-susceptibility genes in dermatitis herpetiformis and psoriasis.

The frequency of an HLA-associated illness-susceptibility (Is) gene can be estimated by a simple equation: the frequency of the Is gene is equal to the prevalence of the disease in the population divided by the penetrance of the illness in first-degree relatives with the HLA marker antigen, with the quotient further divided by two. This equation is valid if the gene is dominant and its gene frequency is low. An analysis of HLA data of 61 patients with dermatitis herpetiformis (DH) showed that the HLA-associated DH susceptibility gene is obviously dominant. The frequency of this DH susceptibility gene was estimated to be at least 0.0005 and the frequency of psoriasis susceptibility gene about 0.02 in Finland.

Dermatitis Herpetiformis↗
PubMed1979

[Genetic distance of the malarial mosquitoes, Anopheles beklemishevi and Anopheles messeae (Diptera, Culiccidae), and their intraspecific polymorphism].

Allele frequencies at enzyme loci have been studied in Finnish populations of two species of the Anopheles maculipennis complex: A. beklemishevi and A. messeae. A. beklemishevi is spread over central and northern Finland, whereas A. messeae is found in southwestern and central Finland. The allele frequencies of these two species exhibit both similarities and differences. The results indicate that the two species do not interbreed in the nature. The allele frequencies at two loci--Hydroxybutyrate dehydrogenase (Hbdh) and Superoxide dismutase-2 (Su-2)--are almost totally different and adult individuals of the two species can be reliably diagnosed by these allelic differences. The genetic distance, D, between A. beklemishevi and A. messeae is 0.35. This value is compared with corresponding distances between other dipterans studied.

Alleles↗
PubMed1978

Monozygous twins discordant for amyotrophic lateral sclerosis.

A pair of identical female twins were discordant for amyotrophic lateral sclerosis. The affected twin was not breast-fed; was bitten by a poisonous snake, and was operated on for struma. She had more infections than her sister but no fractures. Her plasma insulin response to glucose loading was also higher. The twins lived separated in their early childhood.

Adolescent↗
PubMed1978

Dermatitis herpetiformis in Finland.

During a 3 1/2-year period, 492 patients with dermatitis herpetiformis (DH) visited the dermatological departments of Finnish hospitals. The prevalence of DH in Finland was 10.4 patients/100,000 inhabitants, or 1/10,000. About 60 patients contracted DH each year, giving an incidence of 1.3 patients/100,000 inhabitants/year. These figures show that DH is a rather common disease in Finland--much more so in Finland than in Britain. Its incidence does not differ much from that approximated for coeliac disease in Finland. DH occured in all parts of the country. The birth-places of the patients were distributed evenly over the whole country, in contrast to the distribution pattern of rare hereditary diseases in Finland. No significant difference was found in the occurrence of DH in areas with differing levels of wheat consumption or iodine intake.

Adolescent↗
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↗
PubMed1975

Genetic polymorphism and evolution in parthenogenetic animals. II. Diploid and polyploid Solenobia triquetrella (Lepidoptera: Psychidae).

Genic polymorphism at sixteen enzyme loci of four different chromosomal races of Solenobia triquetrella (bisexual, two diploid parthenogenetic races and tetraploid parthenogentiic) has been studied by starch gel electrophoresis. Isolated small diploid bisexual populations have rather uniform allele frequencies at all loci which we have studied. Diploid and tetraploid parthenogenetic individuals of this species are in general as heterozygous as bisexual ones. All parthenogenetic local populations are different from each other in the Alps. These parthenogenetic genotypes cannot be derived from a common ancestor through single mutations but rather bear evidence for a polyphyletic origin of parthenogenesis in Solenobia triquetrella. In the marginal distribution areas of the species in northern Europe single genotypes are spread over far larger areas than in the mountain regions of central Europe. This may be due to the old origin of parthenogenesis and polyploidy in northern Europe. No new parthenogenetic and polyploid strains have lately arisen in the regions outside of the Alps.

Alcohol Oxidoreductases↗