Chitin: New facets of research.

Research on chitin as a marine resource is pointing to novel applications for this cellulose-like biopolymer. Discovery of nondegrading solvent systems has permitted the spinning of filaments, for example, for use as surgical sutures. New methods for preparing the bioactive alkyl glycoside of N-acetyl-D-glucosamine (the monomer unit of chitin) and a microcrystalline chitin has encouraged their use as promoters for growth of bifidobacteria and as an aid in digestion of high-lactose cheese whey by domestic animals. Chitin-protein complexes of several crustacean species show great variability in ratios of chitin to covalently bound protein and in residual protein in the "purified" chitins.

Linkage relationships among loci of polymorphisms in blood and milk of cattle.

Sequential probability tests were employed to examine genetic linkage among, cattle A, B, C, F, J, L, M, S, Z, and R' blood group loci, the hemoglobin locus, the serum transferrin, amylase, and alkaline phosphatase loci, and the milk protein loci beta-lactoglobulin, alpha S1-casein, beta-casein, and kappa-casein. Linkage was evident between the A and hemoglobin loci, the J and beta-lactoglobulin loci, the alpha S1-casein and beta-casein loci, the alpha S1-casein and kappa-casein loci, and the beta-casein and kappa-casein loci. Recombination fractions for these respective combinations were 0, .18, .03, .04, and .06. There was a suggestion of possible loose linkage (recombination fraction = .4) between the beta-lactoglobulin locus and the casein complex. Linkage could be excluded for most other combinations at .25 recombination.

Frequency distribution of genetic markers in Guernsey cattle.

Ten polymorphic systems of blood antigens and blood proteins were analyzed in 6,802 Guernsey cows from 77 herds and 11 states. The numbers of alleles identified with frequencies > 1% in the A, B, C, F, J, L, M, S, and Z blood antigen systems and the alkaline phosphatase system were 3, 17, 11, 2, 2, 2, 1, 3, 2, and 2. Gene frequencies were determined by maximum likelihood, allocation, and square root methods for the dominant systems and by the gene counting method for the codominant system. Distributions varied greatly in the different systems. Comparisons among these and other blood and milk genetic marker systems revealed lack of independence of J and alkaline phosphatase phenotypes, J and milk protein beta-lactoglobulin phenotypes, and of combined phenotypes of the three systems. More cows than expected were J-negative when alkaline phosphatase A was present or when beta-lactoglobulin B was present. Phenotypes of blood antigen system A and hemoglobin were also different from independent assortment. More hemoglobin B cows had blood antigen system A phenotype A than the other phenotypes. The blood antigen locus F had more heterozygous cows than were expected for Hardy-Weinberg equilibrium.

Blood antigen, serum protein, and milk protein gene frequencies and genetic interrelationships in Holstein cattle.

Gene frequencies at ten blood group loci, one serum protein locus, and four milk protein loci were determined for the Holstein-Friesian breed in the United States. The sample consisted of 8630 cows in 51 herds from 10 states. Because of the close linkage among casein subloci and the concimitant rarity of crossover-recombinant groups, casein gene combination or haplotype frequencies were determined also. As one means of comparison of systems, indices of homozygosity and number of effective alleles were calculated. These indices were proposed also to be useful tools for monitoring changes in genetic variability of breeds. Genotypes within codominant systems and phenotypes associated with paired-system combinations generally were not randomly occurring. Paired system phenotypes within the sire sample corresponded much more closely to expectations of randomness.

Antigenicity of bovine milk xanthine oxidase in guinea pigs.

Six female and four male albino guinea pigs were immunized with active purified xanthine oxidase of bovine milk mixed with equal volume of Freund's complete adjuvant. One male and one female were immunized with heat-inactivated xanthine oxidase mixed with equal volume of adjuvant. Two males and four females were controls and received a phosphate buffer mixed with equal volume of adjuvant. The mixtures were administered intradermally and subcutaneously at weekly intervals for 6 consecutive wk and blood samples collected weekly. The enzyme was antigenic by the coated tanned red blood cell method. After the third weekly immunization, precipitating antibodies were in the sera of animals that received the active enzyme. Hemagglutination titers increased during subsequent weeks and reached a maximum after the sixth weekly immunization. Antisera from animals immunized with heat-inactivated xanthine oxidase gave a positive response similar to that with animals immunized with the active enzyme. However, when the same antisera were tested with sheep red blood cells coated with heat-inactivated enzyme, no hemagglutination was observed. Ouchterlony double gel-diffusion tests showed that it may be possible to differentiate between antibodies elicited to active and heat-inactivated xanthine oxidase.