Chromosomal alterations in the karyotype of triticale in comparison with the parental forms

Summary Wheat chromosomes of the primary winter hexaploid and octoploid triticales and of the parental durum and common wheat varieties were studied using morphometric analysis. The size of some heterochromatic segments was shown to change in triticale. Telomeric and intercalary C-bands both increased and decreased in size whereas centromeric bands only increased. The size variability of C-bands in triticale B-genome chromosomes decreased in most of the cases and increased only for several specific C-bands. The C-bands of homologous B-genome chromosomes changed in the same direction in both triticale forms. The changes in size of the C-bands found in R-genome chromosomes detected earlier in these triticale forms (Badaeva et al. 1986) were shown to coincide in their pattern with the size changes of C-bands in homeological B-genome chromosomes. Our data are indicative of regular, directed chromosomal changes in the triticale karyotype.     

Experimental evaluation of the critical size of the myocardial reverberator

Two independent experimental methods for estimating the minimal size of myocardium where a rotating wave could still arise (the crucial wave size) were proposed and realized. The first one was based on measuring the wavelength, the second--on the determination of the crucial size of an unexcited obstacle. The crucial rotating wave size in the myocardium without an obstacle was shown to increase under lidocaine effect.     

Ecological factors influencing the composition of the parasite fauna of the European eel, Anguilla anguilla (L.), in Ireland

The parasites of 121 eels from three contrasting sites in the Corrib catchment area, western Ireland, were investigated. Thirteen species, Ergasilus gibbus, Diplostomum gasierostei, Diplostomum spathaceum, Sphaerostoma bramae. Bothrocephalus claviceps, Proteocephalus macrocephalus, Camallanus lacustris, Cucullanus truttae, Paraquimperia tenerrima, Raphidascaris acus, Acanthocephalus clavula, Acanthocephalus lucii and Pomphorhynchus laevis , were recorded. Two species, P. macrocephalus and P. tenerrima , have not previously been reported from Ireland. Microhabitat preferences of the parasites were noted. Variations in the occurrence and intensities of the parasites observed were analyzed in relation to sampling period, host habitat and characteristics of the eel populations studied. A variety of factors were shown to be of importance, including composition of the fish communities and distributional patterns of intermediate hosts and piscivorous birds. Differences were noted in the parasit-ocoenoses of eels in still and running water sites. The occurrence and intensities of infection of several parasite species were shown to be related to age and size of host: the occurrence of B. claviceps. C. truttae, P. tenerrima and R. acus was shown to be related to either age or size of eels, which is accounted for by the fact that eels become increasingly piscivorous with age and increasing size. Little evidence of interspecific interactions was noted.     

Static intraspecific allometry of the dentition in Otoletnur crassicaudatus

Adult static intraspecific allometry of tooth size was evaluated in a sample of 66 Otolemur crassicaudatus (34 male, 32 female). Tooth areas were calculated from mesiodistal and buccolingual measurements of canines and postcanine teeth of both arcades and were scaled to four viscerocranial measurements: bimaxillary width; maxillo-alveolar length; mandibular length and bigonial width. Individual tooth crown areas were also scaled to total skull length, body length and body weight. From the log-transformed analyses it is concluded that postcanine tooth size was unrelated to body length or weight, and poorly correlated to skull length or jaw size. Although viscerocranial size appears to be independent of body size, these measures are well correlated to skull length. It is shown that the longer the skull, the shorter and narrower the maxilla, and the longer and broader the mandible. Canines are shown to scale negatively allometric to skull length, hence, large animals will have relatively small canines.     

Effect of irradiation on the size of isolated liver mitochondria

The role of external effects in the time course of changes in hepatocyte mitochondria size was studied. Suspensions of mitochondria isolated from the liver of inbred mice were investigated at various periods after gamma irradiation. Statistical analysis of changes in the size of isolated mitochondria has shown that irradiation leads to an increase in mitochondria size, reflected in the distribution pattern. The changes may be related to the functional activity, and distribution shifts may be regarded as manifestations of hepatocyte adaptation.     

The effect of the size of Atlantic salmon, Salmo salar L., eggs on embryos and alevins

A marked diversity in the durations of river and sea existence and the frequency in spawning is shown in the samples of Atlantic salmon females, which were collected over six years. The data are presented on the size and weight of eggs and their dependence on age, and size of females and the time spent at sea. A correlation was established between the size of eggs of embryos and alevins.     

Grazing and the distribution of sediment particle sizes in artificial stream systems

Recent research has shown that grazing by the algivorous minnows of the genus Campostoma can have a significant effect on both structural and functional parameters in stream ecosystems, influencing algal height and type, primary productivity, carbon dynamics, bacterial biomass and the size fractionation of benthic organic matter. This study was undertaken to evaluate the effect of minnow grazing on benthic particulate organic matter (BPOM) under the controlled conditions available in experimental streams. For this study, four grazed and four ungrazed artificial streams were sampled for BPOM on two dates. The samples were partitioned into large, medium, fine and ultrafine fractions via wet filtration. Fish grazed systems had significantly larger percentages of the fine fraction and significantly smaller percentages of the ultrafine fraction. The ability of grazers to alter particle size distribution is important to overall stream organic matter dynamics because recent studies have shown the importance of particle size in determining bacterial numbers and activity, which in turn influence fundamental stream process like respiration and organic carbon dynamics.     

Problems of body structure and size of the hypophysis.

The size of the hypophysis, especially of the anterior lobe, is related to body size while the nervous lobe is related to the brain weight. The anterior lobe of the hypophysis in domestic animals is smaller than that of their ancestors in the wild. The proportions of the body, the distribution of bulk, as they appear in different races--whippets and bulldogs--are related to the size of the anterior lobe. Same body weight implies that the anterior lobe is nearly twice as large in animals with a compact body structure. These intraspecific results can also be shown interspecificly by comparing the species of African Bovidae. Independent of the influence of body size, the subfamilies Alcelaphinae and Hippotraginae possess a larger anterior lobe. A tendency can be shown for a relation to body structure as short-legged species living on marshy grounds (Kobus) or soft sands (Addax) have larger anterior lobes.     

Dimensional characteristics of the Filipino dentition

This study concerns odontometric analysis of the Tagalog Filipinos in Manila, Philippines. Mesiodistal and buccolingual dimensions of the permanent dentition, a total of 56 variables, were studied in 100 males and 152 females. Results showed that their absolute tooth size was small. Relative tooth size, however, seemed to reflect their Southeast Asian Mongoloid origin. From univariate analysis, considerable male-female differences were shown in most of the variables studied. When correlation effects among the teeth were held constant through multivariate analysis, male-female distance was found to be small and substantial overlapping of the two multivariate distributions was evident. Only four variables could be shown by stepwise discriminant analysis to contribute significantly to the distance. Even the mandibular canine, as the strongest discriminator, could only account for 16.4% of the total multivariate distance. These contrasting findings for sex dimorphism in a set of teeth taken singly and taken jointly indicate that there are factors other than the teeth themselves that are expected to play important roles in determining overall male-female size differences in the set of teeth, and that these differences may not be as clear-cut as univariate analysis suggests.     

Cloning in a cosmid vector of complete 37 kb and 25 kb ribosomal DNA repeat units from the chicken

DNA fragments of up to 40 kb containing rRNA-coding sequences have been isolated from a chicken liver DNA library prepared in the cosmid pHC79. Characterization of the cloned DNA by R-loop and restriction mapping has shown that there are two size classes of repeat unit, one of 37 kb and one of 25 kb, the larger of which is a family of units which vary slightly in size. These two classes were shown to be present in the DNA of a single chicken. The size of the internal transcribed spacer in the chicken was measured to be 4.4 kb from analysis of R-loops and heteroduplexes between chicken and Xenopus laevis rDNAs. No introns were observed in either the 18 S or the 28 S coding sequences. The number of copies of the chicken rDNA unit was measured by titration against the cloned sequences to be 202±51 per haploid genome.     

Study of some aspects of the mechanism of bacterial synthesis of silver sulfide nanoparticles by metal-reducing bacteria Shewanella oneidensis MR-1

In the present work it was shown that biosynthesis of silver sulfide nanoparticles from silver nitrate and sodium thiosulfate solutions of millimolar concentration occurs efficiently by living Shewanella oneidensis MR-1 cells, as well as by ultrasonically-disrupted cells and by the membrane fraction of the cells. The size of nanoparticles synthesized in the presence of living cells was 7.8 ± 1.5 nm, while in the presence of ultrasonically-disrupted cells — it was 6.5 ± 2 nm. The shape of nanoparticles in both cases was close to spherical. It was also shown, that synthesis of nanoparticles occurs in a cell-free solution of sodium thiosulfate that has been incubated with cells previously and to which then a silver nitrate solution was added. In this case the nanoparticles were of elongated shape and their size was (11 ± 4) × (24 ± 6) nm. In the control experiment, when only silver nitrate and sodium thiosulfate solutions not incubated with cells were used, the nanoparticles were not detected. It was shown that biosynthesis of nanoparticles occurs both in aerobic and anaerobic conditions. Nanoparticles are not formed by using thermally inactivated cells as it was shown by us previously. The results show the important role of the native structures of cells for the nanoparticles formation.     

On the question of correlation between the size of the epigenetic distance and the degree of allopatry in different populations

The frequencies of discontinuous-varying traits in a Protoslav population (9th century) and an Alamannic population (6th to 8th century) were compared with one another because of their known degree of allopatry. The correlation between this degree of allopatry and the size of epigenetic distance has been shown. Some arguments, e.g. directed gene flow for the calculated distances, have also been discussed.     

Study of the hypothalamus of neonatally castrated rats by the karyometric method]

The sensitivity of different hypothalamic regions to the effect of androgens has been studied during the period of the brain sex differentiation. The castration of animals during the first week of life was shown to result in the marked increase of size of the neuron nuclei in the preoptic, suprachiasmatic, arcuate and ventromedial nuclei of the hypothalamus; the size of neuron nuclei in the dorsomedial nucleus suffered no changes. The dynamics of size of the cell nuclei was followed in different hypothalamic regions with respect to the time of castration.     

Use of pulsed-field-gradient gel electrophoresis to construct a physical map of the Caulobacter crescentus genome

The restriction enzyme DraI cleaves the Caulobacter crescentus genome into at least 35 fragments which have been resolved in agarose gels using pulsed-field-gradient gel electrophoresis (PFGE). When digests were performed using DNA from strains containing Tn5 insertion mutations, altered band migrations were observed. Using PFGE with the appropriate pulse times, size differences as small as 2% could be resolved in large fragments. Using this approach, we have constructed a partial physical map of the genome which correlates well with the C. crescentus genetic map and have shown the size of the genome to be approx. 3800 kb. Using hybridization with cloned genes, we have determined the map locations of five previously unmapped genes. In addition, we have shown that PFGE can be used to rapidly determine the map locations of new insertion mutations or the sizes of deletion mutations.     

Association of D-RNA with Polyribosomes in the Soybean Root

Ribosomes from soybean root tips were shown to consist of about 75% polyribosomes based on size distribution on sucrose gradients. Electronmicrographs showed the presence of ribosome clusters in normal preparations and only monomers and dimers in ribonuclease-treated preparations. The polyribosome preparations, but not single ribosomes, showed good in vitro amino acid incorporating activity.     

Effects of the sequence and size of non-polar residues on self-assembly of amphiphilic peptides

Peptides with alternating hydrophobic and polar amino acids have been shown to form stable beta-sheet secondary structures and self-assemble into hydrogel-like matrices in the presence of physiological salt concentrations. We hypothesized that the sequence and steric size differences of non-polar residues can affect the balance of peptide intermolecular forces in solution that drive self-assembly. To test this hypothesis, we designed a library of artificial amphiphilic peptides based on the sequence (FEFEFKFK)2 by substituting combinations of the non-polar residues glycine, alanine, valine, leucine and isoleucine for phenylalanine. Peptide structure and self-assembly were characterized using scanning electron microscopy, the Thioflavin T assay, transmission electron microscopy, X-ray fiber diffraction and circular dichroism spectroscopy. The sequence and steric size of non-polar residues are shown to cause variations in peptide secondary structures and create significant differences in the matrix morphology of self-assembled peptides.     

Evolutionarily stable strategies and the evolution of life history strategies: I. Density dependent models

The evolution of life history strategies in density dependent situations is considered in both continuous time and discrete time models. The question of equilibrium and of competitively stable strategies, the “invasion” question, are shown to be completely determined by the number of offspring left at a fixed population size. Evolutionarily stable strategies are shown to maximize population size in a certain sense.     

Comparative characteristic of feeding of three species of cottoidei in the littoral of southern Baikal (Cape Berezovyi)

Comparison of the diet and analysis of the size composition of food items in three species of Baikal Cottoidei that inhabit the littoral of southern Baikal (Cape Berezovyi) were performed. The food of the studied species is represented by a wide range of bottom organisms, among which bottom amphipods play a dominant role in all fish. A comprehensive analysis of food composition indicated that the divergence of trophic niches in Cottoidei results from the consumption of different size groups, and, correspondingly, of species of amphipods. The relation between the sizes of prey and the mouth apparatus of the predator is considered as one of the basic reasons of size selectivity. It is shown that the range of the size spectrum of prey in Cottoidei is determined by parameters of the mouth opening in the predator.     

Hybrid protein thymidine kinase gene fusions: plasmid vectors for the study of transcription and translation initiation signals

The thymidine kinase (TK) gene (tk) from Herpes simplex virus type 1 has been used to form gene fusions encoding enzymatically active hybrid proteins. The promoter, translation initiation region, and the first three codons of the tk gene were removed and replaced with a series of DNA restriction sites. DNA fragments containing gene initiation regions were cloned into these sites and shown to synthesize enzymatically active proteins in Escherichia coli. These gene fusions were shown to complement an E. coli strain which is deficient in TK function. Gene initiation regions were used from the lac operon, the tnpR gene of Tn3, and the insA gene of ISl. TK synthesis was regulated by the control signals of the promoter fused to tk, and was dependent upon the phase alignment of the codons at the fusion joint. The size of the resulting protein was shown to be increased over the size of the original TK protein by the length of the coding region fused to TK. This demonstrated that the tk gene has non-essential N-terminal amino acids that can be replaced by other amino acid sequences with the retention of TK enzymatic activity. Such tk gene fusions are useful in situations where fusions with other genes cannot be conveniently selected or assayed.