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.     

Sexual behavior,insemination and development of the freshwater leech Helobdella stagnalis (Annelida,Hirudinea, Glossiphoniidae)

The reproductive biology of the Glossiphoniidae leech Helobdella stagnalis, under laboratory conditions, the structure of its eggs and its developmental stages were studied. Sperm transfer and insemination are made by hypodermic injection: one or numerous spermatophores were attached to the skin of the partner during copulation and sperm is injected through it. The leeches can copulate repeatedly with several partners. Each leech produces 4–8 cocoons containing 20–60 eggs whose are attached to the ventral side of the parent and carried around. At 22 °C, the developmental duration is 24 days from the oviposition until the juveniles leave the parent leech. Three (3) major stages have been distinguished: Eggs cleavage, germinal band generation, and juveniles hatching. The sexual behavior of Hellobdella stagnalis was described with a special attention given to parental care.     

Experimental investigation of the scaphoid strain during wrist motion

The scaphoid is the most frequently fractured of the carpal bones [Taleisnik, J., The Wrist, Churchill Livingstone, New York (1985)]. This project was undertaken to qualitatively evaluate the strain in the scaphoid during wrist motion using a newly developed strain gage method. Strain gage resettes were mounted within the scaphoid and the range of motion of the hand was monitored using a custom designed electrogoniometer and data acquisition system. Ten specimens were utilized for this study. Results indicated that supination/pronation (S/P) of the forearm did not affect the strain in the scaphoid. A map of the strain in the waist of the scaphoid, as a function of flexion/extension (F/E) and radial/ulnar deviation (R/U), was generated. The contour plot of scaphoid strain vs range of motion (ROM) shows a valley where strains are low. Minimum scaphoid strain was found near neutral F/E and 15° of ulnar deviation.