Three polymorphic microsatellite loci were isolated and employed to examine paternity patterns in two natural populations of live‐bearing mosquitofish, Gambusia holbrooki. Each locus displayed four to five alleles per population in samples of presumably unrelated adults. Nearly 900 embryos from a total of 50 pregnant females were assayed individually, and paternal alleles in each embryo were identified. Counts of paternal alleles, Mendelian segregation patterns, multilocus allelic associations and genetic relatedness coefficients were employed to estimate the minimum and effective numbers of fathers per brood. At least 90% of the assayed broods were shown to have been fathered by multiple males, a figure substantially higher than previous estimates based on less polymorphic genetic loci. However, the genetic data yield a face‐value estimate of only about 2.2 fathers per brood, a number that seems perhaps surprisingly low based on frequencies of attempted copulations by males. Both biological and sampling factors that might bias mean sire counts downward are considered. Although higher sire counts per brood might be obtained from loci with even greater numbers of alleles, little statistical room remains for higher frequency estimates of multiple paternity in Gambusia.
The prevalence of intracranial haemorrhage (ICH) in our population of haemophiliacs was 12%. The incidence of ICH was approximately 2% per year. At entry, 7% (21/309) had clinical histories of ICH without MRI evidence of old haemorrhage, indicating that either the haemorrhages had completely resolved, that routine MRI sequences are not particularly sensitive for the detection of old blood products, or a combination of both of these factors. One half (4/8) of the ICHs documented by entry MRI were clinically silent, and three of the 11 incident cases documented by MRI were clinically silent. HIV infection did not increase the risk of ICH.
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