The effect of rumen ciliates on chitinolytic activity,chitin content and the number of fungal zoospores in the rumen fluid of sheep

The objective of this study was to investigate the effect of selected protozoa on the degradation and concentration of chitin and the numbers of fungal zoospores in the rumen fluid of sheep. Three adult ewes were fed a hay-concentrate diet, defaunated, then monofaunated with Entodinium caudatum or Diploplastron affine alone and refaunated with natural rumen fauna. The average density of the protozoa population varied from 6.1 · 10⁴ (D. affine) to 42.2 · 10⁴ cells/ml rumen fluid (natural rumen fauna). The inoculation of protozoa in the rumen of defaunated sheep increased the total activity of chitinolytic enzymes from 2.9 to 3.6 μmol N-acetylglucosamine/g dry matter (DM) of rumen fluid per min, the chitin concentration from 6.3 to 7.2 mg/g DM of rumen fluid and the number of fungal zoospores from 8.1 to 10.9 · 10⁵ cells/ml rumen fluid. All examined indices showed diurnal variations. Ciliate population density was highest immediately prior to feeding and lowest at 4 h thereafter. The opposite effects were observed for the numbers of fungal zoospores, the chitin concentration and chitinolytic activity. Furthermore, it was found that chitin from zoospores may account for up to 95% of total microbial chitin in the rumen fluid of sheep. In summary, the examined ciliate species showed the ability of chitin degradation as well as a positive influence on the development of the ruminal fungal population.     

Substrate properties of C'-methylnucleoside triphosphates in a reaction of RNA synthesis catalyzed by Escherichia coli RNA-polymerase

2 theta-C-methyl substituted and phosphonate analogs of UTP were prepared and together with the synthesized earlier 3'-C-methyl-UTP were investigated in the RNA synthesis reaction catalysed by Escherichia coli RNA-polymerase. Substrate properties of UTP analogs were studied in the presence of all natural triphosphates, in the absence of UTP and under conditions of soil substrate reaction. It was shown that UTP(3'CH3) is incorporated into the RNA chain and terminates further RNA elongation. Another analog UTP (2'CH3) may substitute natural UTP in RNA synthesis, but the effectivity of its incorporation is diminished. Phosphonate analog UTP(5'CH2) is a pseudoterminator of RNA synthesis. The conformational analysis of 2'- and 3'C-methylnucleosides by force-field method of calculation was carried out in order to find energetically forbidden conformations of these analogs due to the collision of bulky methyl group and a heterocyclic base. An attempt was made to fix the conformation of the substrate during its enzymatic transformation.     

Chromosome replication in four species of snakes

Chromosome measurements were performed in four species of snakes related at the level of suborder (Boa constrictor amarali, Xenodon merremii, Philodryas patagoniensis, Bothrops jararaca). The data obtained point out that pairs 1–3 were common to the four snakes and probably inherited from the ancestor of the suborder Serpentes. Pairs 5–8-W were characteristic of each snake; hence, it is possible to assume that they followed evolving after the appearing of the suborder Serpentes. Z-chromosomes were metacentric in B. constrictor amarali, X. merremii and B. jararaca and slightly submetacentric in P. patagoniensis. Area of these chromosomes varied from 8.6–10.6% of the haploid set in the four species studied.-The study of chromosome replication at the end of the S period points out that shared chromosomes have similar patterns of labeling. Therefore, it is proposed that the distribution of late replicating regions and heterochromatin in the genome is phylogenetically transmitted and probably genetically determined.—The analysis of the ending-sequence of chromosome replication shows that sex chromosomes finish earlier than macroautosomes. It is concluded that snakes probably have no mechanism of sex chromosome heterochromatinization in either sex. The absence of late replicating Z-chromosome in the males, favours the hypothesis that no mechanism of sex dosage compensation is acting in the suborder Serpentes.This work was partially supported by Public Health Service Research grant No. GM-14577-03 from the National Institute of General Medical Sciences and by the Fundo de Pesquisas do Instituto Butantan.     

The effect of (2-chloroethyl) trimethylammonium chloride on ethylene evolution and respiration rate of an early cultivar of apples

Ethylene production and respiration rate of an early cultivar of apples, Letní pr?svitné ?luté, is significantly increased after the application of the lowest tested concentration of CCC (0.1% in lanolin). These effects, calculated from the amount of released ethylene and carbon dioxide, were observed during the whole period of ripening. The production of ethylene is slightly inhibited by the higher concentrations of CCC while the respiration rate is not significantly affected. The rate of the ethylene production of the early cultivar of apples is decreased 4.4 to 9.7 fold by 0.1% CCC as compared with the winter cultivar Jonathan. Although these ratios rise gradually during the ripening of fruits treated with other higher concentrations of CCC, the total amount of ethylene produced by the winter cultivar Jonathan is 1.5 fold higher than that of the early one.     

Cytological evidence of constant tetraploidy in the bisexual South American frog Odontophrynus americanus

Odontophrynus americanus has 2n=44 chromosomes in somatic and gonad cells which can be ordered in 11 groups of homologues. In spermatocytes I they form mostly ring quadrivalents. In metaphase II 22 dyads are present. There is no indication of abnormalities in and gonad development.     

Electron microscopic research on cryptosporidia. III. Parasite-host relations

A study was made of the host-parasite relationship with Cryptosporidium parvum (Apicomplexa, Sporozoa), which parasitizes the intestine of newborn rats experimentally infected with oocysts isolated from C. parvum-infected calves. The endogenous development of the parasite occurs extracytoplasmically in the microvillar compartment of the enterocytes. The formation of the extracytoplasmic parasitophorous vacuole (PV), like that surrounding the endogenous stages of C. parvum, is regarded as one of the possible and evolutionary established ways for the intracellular parasite to escape from the host cell lysosomal digestion. Special attention is paid to the attachment zone of C. parvum, where a multimembranous organelle is formed serving eventually as a feeder organelle. No other specialized cytostome, similar to the micropore of other coccidia, has been so far revealed in the growing stages of Cryptosporidium. The characteristic ultrastructural organization of the endogenous stages of C. parvum and of other Cryptosporidium species so far investigated, along with the peculiar structure of the cryptosporidia-surrounding PV, to say nothing of some other distinctive features--all this makes it possible to distinguish between the genus Cryptosporidium and other coccidian genera, and warrants the separation of the former into a separate family Cryptosporidiidae Léger, 1911. Unlike, the addition to this family, besides Cryptosporidium Tyzzer, 1910, of another genus, Epieimeria Dykova, 1981, on the ground of the "epicellular" localization of both the genera claimed by Levine (1984), seems hardly correct, due to the totally different patterns of ultrastructural organization and host-parasite relationship recently reported for Epieimeria anguillae by Molnar and Baska (1986).     

A simple method of purifying staphylococcal alpha-toxin and a study of its properties]

The simple method is proposed for isolation and purification of staphylococcal alpha-toxin that permits one to obtain the homogeneous toxic protein with high activity. The time necessary for maximal toxin production at cultivation has been defined. The thermostability and interferonogenic characteristics of the obtained alpha-toxin were studied.     

Substitution analysis of callus induction and plant regeneration from anther culture in wheat (Triticum aestivum L.)

The genetic determination of callus induction, total plant regeneration and green plant regeneration from anther culture were studied using a Chinese Spring/Cheyenne substitution series. All the three characteristics were found to be polygenically determined, but their inheritance was independent from one another. The 7A and 18 chromosomes had a considerable effect on callus induction. In the case of total plant regeneration the most influential chromosome as the 3A while the 2D chromosome showed a definite influence on green plant regeneration. The interaction between the genetic background of the recipient plant and the substituted chromosome plays an important role in the manifestation of the studied features.