The Distribution of Halogeton Sativus (L.) C. A. Meyer in Morocco

In the search for natural enemies of Halogeton glomeratus (Bieb.)C. A. Meyer, a noxious weed introduced into the United States,studies were made, in 1959-61, on the distribution of H. sativus,a closely related species, occurring within Morocco. This plantis found in the Rif Mountains in the north, throughout the MoulouyaRiver Valley, along the Ziz River Valley, scattered along thesouthern slopes of the High Atlas Mountains as far west as Amerzgane,with an apparently discontinuous area of distribution on thenorthern slopes of the High Atlas in the vicinity of Asni.     

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.