A mutation in FBN1 disrupts profibrillin processing and results in isolated skeletal features of the Marfan syndrome.

Dermal fibroblasts from a 13-yr-old boy with isolated skeletal features of the Marfan syndrome were used to study fibrillin synthesis and processing. Only one half of the secreted profibrillin was proteolytically processed to fibrillin outside the cell and deposited into the extracellular matrix. Electron microscopic examination of rotary shadowed microfibrils made by the proband's fibroblasts were indistinguishable from control cells. Sequencing of the FBN1 gene revealed a heterozygous C to T transition at nucleotide 8176 resulting in the substitution of a tryptophan for an arginine (R2726W), at a site immediately adjacent to a consensus sequence recognized by a cellular protease. Six other individuals in the proband's family had the FBN1 mutation that segregated with tall stature. None of the affected individuals have cardiac or ocular manifestations of the Marfan syndrome. This mutation identifies a putative site for profibrillin to fibrillin processing, and is associated with isolated skeletal features of the Marfan syndrome, indicating that the FBN1 gene is one of the genes that determines height in the general population. The cellular effect of the mutation may be equivalent to a "null" FBN1 allele and may define the phenotype associated with FBN1 "null" alleles.

A comparison of life span characteristics in Drosophila.

A comparison of life span characteristics in 12 Drosophila species representing different degrees of phylogenetic relatedness and various ecological backgrounds was undertaken. Survival curve, LT50, LT100, range and mortality rate were compared at three different levels: intraspecific (male-female); interspecific (within species group triads); intergroup (among species group triads). Data indicate that when differences are found within species groups, there is greater similarity between more closely related taxa. At all levels of comparisons, differences cannot be used to predict from one characteristic to another or from one sex to the other. The influence of both phylogenetic and ecological factors on patterns of results are evaluated, as well as the suggestion that at least two different mechanisms of aging may exist in the genus Drosophila. The observed diversity in life span characteristics among Drosophila species groups and similarity within species groups, demonstrate the value of a comparative approach for studying aging.

Geographic distribution and light-dependent behavior in Drosophila.

Drosophila species fall into three classes with respect to the effect of light on their reproductive behavior: Class I, species that mate equally well in light or darkness; Class II, those merely inhibited by darkness; Class III, species whose mating is blocked by darkness. Species in the three classes also differ in the extent of their geographic distribution, with Class I including widely distributed and cosmopolitan species and Class III those that are endemic. Class II species have an intermediate distribution pattern. The behavioral differences among species reflects the degree to which courtship information is locked-in on unique visual stimuli, as well as indicating differences in the underlying genetic architecture of flexible versus specialized forms. It may be anticipated that most species of Drosophila will be found light dependent. Similar organizational differences in other forms relying on visual courtship stimuli may be reflected in correlation between distribution and behavioral reliance on a single sensory input. Dependence on a single sensory input offers a unique variety of methods for biological control of species that requires a particular sensory system for information transfer.

Pupation-temperature range in 12 Drosophila species from different ecological backgrounds.

A comparison of pupation-temperature range was made in the laboratory on a temperature gradient (3-38 degrees C) using 12 species of Drosophila representing four species groups and four different ecological backgrounds (temperate-montane forest: virilis group; desert: repleta group; cosmopolitan: melanogaster group; tropical forest: willistoni group). Within groups, differences are found which usually reflect species' distributions. Comparisons of species' mating-, oviposition- and pupation-temperature ranges reveal that pupation most often occurs at temperatures beyond those for mating and oviposition. Each species reflects a different combination of temperature effects. Individual species have different temperature-limits for mating, oviposition and pupation. Temperatures permissive for one response are not predictive of limits on other responses. Among species, temperature can affect a particular response differently. Within groups, species differences can be at high and/or low temperatures for any response, and temperature effects among closely related species can manifest themselves in one, or any combination of responses. One cannot predict which responses will be most and least limited, or at which end of the temperature scale a response will be most limited. Among groups, common, but not absolute temperature ranges generally correspond to the geographic distributions and ecological backgrounds of the species triads. The evaluation of temperature effects on species, based on a single activity, may not be adequate for predicting adaptive strategies.

Functional relationships between genotypes and environments in behavior. Effects of different kinds of early social experience on interstrain fighting in male mice.

Comparisons are made of the interstrain fighting behavior of adult male mice from two inbred strains (ST-albino; CBA-black-agouti), raised in one of three postweaning social situations: 1) isolated from other males, 2) reared with males of the same strains, or 3) reared with males of the opposite strain. Using the fighting behavior of isolated males as a baseline, it is found that each type of early social experience affects the fighting behavior of the males from each of the two inbred strains differently, indicating that the functional relationships between genotype and environment studied in these experiments are nonadditive. The importance of these results in describing the norm of reaction of a behavioral phenotype and in extrapolating data from one experiment to another is discussed.

Isoenzyme status and genetic variability of serum esterases in the lesser snow goose, Anser caerulescens caerulescens.

A maximum of 22 bands comprising four esterase subgroups--acetylesterase, carboxylesterase, cholinesterase, and acetylcholinesterase--were detected following electrophoresis of lesser snow goose sera on polyacrylamide gels. A minimum of seven structural genes was surmised to be involved in the biosynthesis of these enzymes following physiochemical characterizations. The genetic variability of these loci was calculated to be 1.25% average heterozygosity, while 14.3% of the loci were polymorphic. These estimates of genetic variability were substantially lower than those reported for other vertebrate species. The low degree of genetic variability found in snow goose serum esterases coupled with the extensive protein multiplicity observed may possibly reflect an adaptive strategy based on "biochemical plasticity" rather than genic heterozygosity for this species. The nature of evolutionary forces acting upon multiple enzyme systems such as esterases is discussed. The concept of "conditional neutrality" is introduced and defined within this context.