Comparative study of biological and technological characters in three generations of silkworm Bombyx mori L. ameiotic, parthenogenetically cloned lines.

PURPOSE: Detect any deviation in biologic and technologic characters of eight ameiotic-parthenogenetically cloned lines of Bombyx mori L. from different origins from a normal sexually reproduced control line in three generations. METHODS: Comparative study of the three generations was conducted in SES, Vratza, unit of the National Center for Agrarian Sciences of Bulgaria after fixing all environmental rearing conditions. RESULTS: The ameiotic-parthen-clones displayed good parthenogenetic development, although total hatchability was significantly less than the sexually reproducing control populations. Survival rates between clones and control were not significantly different. All clones displayed significantly longer larval periods. Slight decline in second generation, and a steeper one in the third generation were observed for all eight cloned lines in cocoon weight, shell weight, and shell ratio and these differences were statistically significant. Cocoon yield was significantly lower than the control throughout the three generations. CONCLUSIONS: Our parthen-cloning method has a high rate of success in comparison to other cloning methods, the cloned progeny populations although were weaker technologically (cocoon weight, shell weight, and shell ratio), the biological characters (parthenogenetic development and survival rate) were not compromised. Further study is needed to determine the thermal needs of the cloned embryos and metabolic rate of all stages.

[Sperm foreward movement in the female genital tract of sheep]. / Izsledvane vurkhu pridvizhvaneto na spermatozoidite v zhenskiia polov aparat pri ovtse.

Investigations were carried out to establish the effect of deep freezing, extent of dilution, and site of applying the spermatozoa as well as the functional state of the female genital apparatus of sheep on the forward movement of spermatozoa. It was found that at the insemination of ewes with freshly obtained undiluted semen at the 30th min following insemination there were single live spermatozoa, in the oviducts their number gradually increased up to the fourth hour, reaching several thousand. The highly diluted semen was found to produce an unfavourable effect on the movement of spermatozoa. Following deep freezing spermatozoa manifested a sharp decrease in their movement capacity. Deep cervical application led to an increased number of spermatozoa reaching the oviducts, however, this number was essentially lower than with freshly obtained semen. The movement of spermatozoa depended also on the functional status of the female sexual apparatus. There were considerably more spermatozoa in that of the oviducts on the side of which ovulation took place.

[Complex-forming factors in the dilution of bull sperm for deep freezing]. / Kompleksoobrazuvashti faktori pri razrezhdane na sperma ot bik za dulboko zamraziavane

Micro- and ultramicroelectrophoresis on Cellogel were employed to study the formation of complexes of bull's semen and the constituents of Nagaze-Niva's extender in all possible combinations. It was found that a new glycoprotein complex is formed in mixing the semen with yolk. This complex was found to bind 82 +/- 1.5 per cent of all proteins in the sample. The addition of lactose to the yolk-diluted semen was shown to lead to the dispersion of this complex into 4--5 subunits. The cation fraction of the semen plasma and glycerin were established to take no part in the complex formation. Discussed are the problems associated with the dispersion effect of lactose and the higher (twice to three times) survival rate of semen trated with extenders containing saccharides.