First International Workshop on Porcine Chromosome 6

Recent advances in the use of microsatellite markers and the development of comparative gene mapping techniques have made the construction of high resolution genetic maps of livestock species possible. Framework and comprehensive genetic linkage maps of porcine chromosome 6 have resulted from the first international effort to integrate genetic maps from multiple laboratories. Eleven highly polymorphic genetic markers were exchanged and mapped by four independent laboratories on a total of 583 animals derived from four reference populations. The chromosome 6 framework map consists of 10 markers ordered with high local support. The average marker interval of the framework map is 15.1 cM (sex averaged). The framework map is 135, 175 and 109 cM in length (for sex averaged, female and male maps, respectively). The comprehensive map includes a total of 48 type I and type II markers with a sex averaged interval of 3.5 cM and is 166, 196 and 126 cM (for sex averaged, female and male maps, respectively). Additional markers within framework map marker intervals can thus be selected from the comprehensive map for further analysis of quantitive trait loci (QTL) located on chromosome 6. The resulting maps of swine chromosome 6 provide a valuable tool for analysing and locating QTL.     

The Fine Structure of the Gregarine Lankesteria culicis Parasitic in the Yellow Fever Mosquito Aedes aegypti

SYNOPSIS. The fine structure of the eugregarine Lankesteria culicis from the larvae of the mosquito Aedes aegypti was examined by light and electron microscopy and compared with that of other gregarines. The cell organelles found in L. culicis included a nucleus, mitochondria, Golgi-complexes, endoplasmic reticulum, vesicles, droplets, granules and lipid bodies.
The surface of L. culicis was composed of a highly differentiated membrane-cortex, differing slightly from that of other eugregarines. This complex was limited by a unit membrane, the plasmelemma, and underlying cortical laminae which appeared to be composed of several layers. The homogeneous electrondense layer present in Pyxinoides balani was greatly diminished or absent in L. culicis.
A series of laminar folds supported by ground substance and longitudinal subpellicular fibrils gave the organism's surface a ridge-like appearance. Permanent cytostome-like openings in the surface, which appeared to be supported by a narrow band of thickened cortex, were present as specializations of the surfacemembrane complex. The structural composition of the parasite appeared quite striking in that it was made up almost entirely of vesicles, granules, and droplets which were absent only in the area of the protomerite. The mitochondria were usually found just beneath the surface or near the nucleus. Mitochondria were also seen in the region of demarcation between the protomerite and deutomerite.     

Reproductive Effects of the Mammalian Pineal

The reproductive systems of mammals are anatomically and physiologicallyaltered by the pineal gland. Characteristically, pineal removalaccelerates gonadal growth in immature animals and causes atransient modest enlargement of the reproductive organs if theoperations are done after adulthood is attained. Light deprivationrenders the pineal strongly antigonadotropic. In addition, thereare several conditions, e.g., androgen-sterilization and anosmia,which potentiate, probably indirectly, the gonad-inhibitingcapability of the rat's pineal. The chronic administration ofpineal extracts or pineal substances has effects opposite topinealectomy, i.e., they restrict gonadal development or growth.The pineal is possibly important in adjusting the level of reproductiveactivity to seasonal changes in environmental conditions.     

SOME SOURCES OF BIAS IN CONSUMER TESTING

Data sets from three studies were examined to determine the effects of brand identification and package design on consumer responses during product evaluation. In these studies, consumers evaluated products with or without brand identification, compared products in standardized conditions, and compared products in different package designs with different or identical product contents. Measurement of consumer responses for all studies was based on 9-point hedonic scale. The results of the study showed that consumers were less critical in their evaluation when the samples being assessed were identified by brand names. Brand identification and package design, when not concealed in the comparison of product contents, resulted in consumer response bias. Also, the popularity of a brand influenced consumer's perception of products.     

The crenellate lining of the Dufour gland in the genus Aenictus: a new character for interpreting the phylogeny of Old World army ants (Hymenoptera, Formicidae, Dorylinae)

The Dufour gland epithelium in Aenictus has a crenellate appearance, a condition previously found only in the primarily African genus Dorylus . This character, taken alone, strongly suggests that these two genera share a common ancestry, as is presently reflected in their placement in the subfamily Dorylinae, and that an independent, convergent origin for them, as has been proposed in the triphyletic hypothesis for army ant evolution, is incorrect.     

Iterative evolution of Middle Jurassic ammonite faunas

The phenomenon of iterative evolution of homeomorphs in identical temporal sequences is exhibited by Aalenian and Bajocian ammonite faunas in the south German depositional basin. Within each evolutionary cycle, inflated, evolute, and ornamented shells with complex suture lines are successively replaced with discoidal, involute, smooth shells with simpler sutures. Three distinct and identical cycles of morphological change occur, and involve ammonites belonging to four different familial/subfamilial groups: the Leioceratinae, Graphoceratinae, Hammatoceratidae, and Sonniniidae. Geometric and statistical analyses of morphological change within each of these higher taxa reveal remarkable iteration in both the pattern and proportion of change with time. The iterative morphological cycles were not driven by orthogenesis or anagenetic transformation within lineages, as has been previously suggested. A clear correlation exists between the successive ammonite faunas and repeated cyclical changes in the physical marine environment of the depositional basin. D Ammonoidea, Aalenian, Bajocian, south Germany, iterative evolution.     

Spores of a New Microsporidan Species Parasitizing Molluscan Neurons

Synopsis.
A new species of Microsporida was observed in neurons of the marine mollusc Aplysia californica and the ultrastructure of its spores was investigated. The spores were ˜ 1.3 m long and had a thick 3-layered coat. An anchoring disc and polar aperture were present. The polaroplast occupied most of the anterior half of the spore. The vesicular portion included lengths of loosely packed lamellar structures as well as the usual vesicular profiles embedded in fibrillar material; it was entirely surrounded by tightly packed, electron-dense lamellae. The polar tube had 5 or 6 coils. In this stage of the life cycle (mature spores), the parasites did not appear to be disturbing the host cells. The organism was named Microsporidium aplysiae sp. n.