Effect of habitat, date of laying and density on clutch size of the Great Tit Parus major in northern Finland

The sizes of 1034 Great Tit clutches were studied at the Oulu area (c. 65°N, 25°30'E) in northern Finland. The average size was 9.86 eggs in the first clutch and 7.51 in the second in 13 study areas. The decrease in clutch size from the first to the second laying was most pronounced in those females laying the largest first clutches.
Irrespective of habitat, the clutch size was larger in the sparsely populated areas than in the densest area (Taskila). The clutch size decreased according to the season in all the areas, but this was not as pronounced in Taskila as in the other areas.
The annual average size of the first clutches was inversely related to the breeding density and pronouncedly so to the mean dale of laying. The latter was suggested to be an adaptation to the short season in the northern areas.
An analysis of data from 27 study areas in Europe, north of the Mediterranean region, suggests that the clutch size does not vary with latitude or longitude.     

Genetic diversity and population structure in the outcrossing populations of Equisetum arvense and E. hyemale (Equisetaceae)

An allozyme examination was conducted to study the mating systems and genetic differentiation of populations of Equisetum arvense and E. hyemale. The study revealed that the rate of intragametophytic selfing in these homosporous pteridophytes is very low, i.e., on average 0.020 and 0.019, respectively, despite the potential hermaproditism and selfing of the gametophytes. Most populations consisted of numerous genotypes, and the average heterozygosities of E. arvense and E. hyemale equalled 0.092 and 0.134, respectively. The commonly observed excess of the heterozygote genotypes indicates that there are interclonal differences in the frequency of vegetative reproduction. The level of genetic divergence among populations was considerable even within a limited geographic area. It is suggested that the life history of Equisetum, characterized by the inefficiency of spore germination and gametophyte reproduction in noncolonizing situations, limits the level of gene flow and leads to a great genetic divergence between populations.     

Immunoperoxidase staining of carcinoembryonic antigen with monoclonal antibodies in adenocarcinoma of the colon

Summary Mouse monoclonal antibodies to carcinoembryogenic antigen (CEA) obtained by the somatic cell hybridization technique of Köhler and Milstein were used in a modified enzyme bridge immunoperoxidase staining method. Both high and low affinity antibodies were tested and their staining properties compared with those of a commercial polyvalent rabbit antiserum. The staining pattern of neoplastic epithelial cells in all seven antibodies in samples of primary adenocarcinoma of the colon was similar, indicating that no gross differences were found in the exposure of the different antigenic determinants of CEA in formalin fixed tissue. The background staining of the monoclonal antibodies was negligible. It is concluded that monoclonal antibodies are superior to conventional antisera in immunoperoxidase staining of CEA.     

Interpopulation genetic divergence in European grayling (Thymallus thymallus, Salmonidae) at a microgeographic scale: implications for conservation

In order to provide guidelines for conservationand management of the severely declining LakeSaimaa (eastern Finland) European grayling(Thymallus thymallus, Salmonidae), weinvestigated the microgeographic geneticstructure of three populations from the watersystem using 17 microsatellite loci andmitochondrial DNA polymerase chainreaction-restriction fragment lengthpolymorphism analysis. Microsatellites revealedlow levels of intrapopulation genetic diversityand substantial divergence between populationssampled from spawning sites separated by aslittle as 55 kilometers. Mitochondrial analysisindicated the occurrence of two compositehaplotypes within Lake Saimaa. The nucleotidesubstitution estimates between the haplotypessuggested their separation to markedly predatethe late Pleistocene period. The populationsexhibited marked frequency differences for thetwo mitochondrial haplotypes, reinforcing theview of limited interpopulation gene flowwithin Lake Saimaa. An individual basedmicrosatellite Neighbor-Joining dendrogramdemonstrated clustering of all the specimensaccording to their sampling origin. Individualassignment tests revealed 100% assignmentsuccess of individuals into their population oforigin and 100% exclusion (p <0.05) from all alternative referencepopulations. These findings exemplify that T. thymallus populations may be genetically highly structured over small geographical scales and provide a good starting point for the development of appropriate conservation strategies for Lake Saimaa grayling.     

Heterozygosity excess at the cattle DRB locus revealed by large scale genotyping of two closely linked microsatellites

A method for MHC DRB typing in cattle based on two closely linked and highly polymorphic microsatellites is described. The two microsatellites DRBP1ms and DRB3ms are located in intron 2 of the corresponding DRB gene. The very strong linkage disequilibrium between the two loci made it possible to establish DRB microsatellite haplotypes. The typing results with this method on reference samples followed closely that obtained with RFLP and direct sequence analysis of DRB3 exon 2. The method is well suited for large scale genotyping and was successfully applied for typing more than 600 unrelated animals representing 23 breeds. The data were used to test whether the observed DRB allele frequency distributions were consistent with that expected for selectively neutral alleles in populations at mutation-drift equilibrium. A significant heterozygosity excess was detected and there was an obvious trend across breeds towards a more even allele frequency distribution than expected. The deviation may be due to balancing selection acting on the DRB locus or by recent population bottlenecks.     

Familial Migraine: Exclusion of the Susceptibility Gene from the Reported Locus of Familial Hemiplegic Migraine on 19p

Genetic isolates are highly useful in analyses of the molecular background of complex diseases since the enrichment of a limited number of predisposing genes can be predicted in representative families or in specific geographical regions. It has been suggested that the pathophysiology and etiology of familial hemiplegic migraine (FHM) and typical migraine with aura are most probably the same. Recent assignment of FHM locus to chromosome 19p in two French families makes it now possible to test this hypothesis. We report here linkage data on four families with multiple cases of migraine disorder originating from the genetically isolated population of Finland. We were interested to discover whether the migraine in these families would also show linkage to the markers on 19p. We could exclude a region of 50 cM, flanking the reported FHM locus, as a site of migraine locus in our four families. It seems evident that locus heterogeneity exists between different diagnostic classes of migraine spectrum of diseases and also between different ethnic groups.