[The impact of migration on regional demography]. / Bliyanie na migratsiyata barkhu formiraneto na regionalnata demografska situatsiya.

PIP: Patterns in internal migration over the past 10 years in Bulgaria are reviewed, and the regional demographic impact is assessed. The authors observe an uneven distribution of the population among regions and an overgrowth of the larger cities. Government policies to regulate internal migration are outlined. (SUMMARY IN ENG AND RUS)^ieng

[Effect of cryopreservation on the acrosomal enzyme activity of the spermatozoa of rams]. / Vliianie na kriokonservatsiiata vurkhu aktivnostta na akrozomalnite enzimi na spermatozoidi ot koch.

Studied was the effect of cryoconservation on the activity of acrosine and acrosomal acid phosphatase of spermatozoa of rams stored in the form of pellets with the use of a diluent after Nagaze-Niva. It was found that the activity of acid phosphatase dropped by 35 per cent when stored in the course of 24 hours and 7 days. Acrosine was shown to be more stable at cryoconservation--its activity did not change under the same conditions of storing, however, it dropped by 30 per cent for 7 days. Admittedly, one of the reasons for the drop of the fertilizing capacity of ram spermatozoa after freezing was the drop of acrosomal enzyme activity. Most probably, the noxious factors were two--ultralow temperatures, and storage duration of spermatozoa.

[Effect of ultra low temperatures on the acrosomal proteins of bull and ram spermatozoa]. / Vliianie na ultraniskite temperaturi vurkhu akrozomalnite beltutsi v spermatozoidi na bik i koch.

Tested was the effect in vitro of ultra low temperatures on the activity of the acrosomal enzymes--acrosine and acid phosphatase--in the spermatozoa of bulls and rams. The use of spectrophotometric and electrophoretic methods demonstrated the presence of certain differences in the electrophoretic profile of the studied enzymes so far as spermatozoa of bulls and rams were concerned. Besides, acrosine and acid phosphatase in the acrosomal extracts from ram spermatozoa showed higher lability in treatment with ultra low temperatures as compared to bull spermatozoa. This led to higher losses with regard to some biologic properties of ram spermatozoa following the use of a technology of deep-freezing of semen.

[Activity and molecular forms of nicotinamide adenine dinucleotide- and nicotinamide adenine dinucleotide phosphate-dependent malate dehydrogenase in bull spermatozoa]. / Avtivnost i molekuliarni formi na nikotinamidadenindinukleotid- i nikotinamidadenindinukleotidfosfat-zavisimata malatdekhidrogenaza v spermatozoidi na bik.

Investigations were carried out on the activity and the isoenzyme composition of the NAD- and NADP-dependent malatedehydrogenase in the soluble and sedimental proteins of bull spermatozoa. It was found that the activity of the NAD-dependent malatedehydrogenase was higher than the activity of the NADP-dependent one both in the soluble and in the sedimental proteins. The difference in the activity was spectrophotometrically and electrophoretically demonstrated.

[Activity and isoenzyme pattern of alkaline and acid phosphatases in bull seminal plasma]. / Aktivnost' i izoenzimnaia model' shchelochnoi i kisloi fosfatazy v semennoi plazme bykov.

Investigations are carried out on the activity and isozyme pattern of the alkaline and acid phosphatases in bull's seminal plasma. To determine the activity of the two phosphatases, two different colorimetric methods are used. The electrophoretic separation of the isozymes of the acid and alkaline phosphatases is performed on polyacrylamide and starch gels.

[Fructose and the fructolysis index in bull semen]. / Fruktoza i fruktolizen indeks v spermata na bitsi

The fructose content and the fructolysis index were studied in the semen of bulls. It was established that the value of the index depends upon the age. Highest values were found with the semen of 2-year-old bulls (3.23 +/- 0.13), and lowest were the values in bulls aged from 5 to years (2.49 +/- 0.12). It was also found that in September-October the fructolysis index is higher than the values in March-May. No differences were observed with the content of fructose.