Governing equations of motion for the otolith organs and their response to a step change in velocity of the skull

The otolith organs are the linear motion sensors of the inner ear. They comprise an overdamped second-order system and respond to gravity and skull acceleration. The governing equations of motion which describe the relative displacement of the mass with respect to the skull are developed. When these equations are non-dimensionalized they indicate that the elastic term is almost negligible with respect to the viscous and inertial terms. For a step change in skull velocity an analytic solution is given for the elastic term equal to zero and numeric solutions are given for small values of the elastic term.     

Bacteriocinogenicity of brucellae isolated in foci in the Caucasus and their evaluation from taxonomic viewpoints

The aim of the study was to elucidate the possibility of using bacteriocinogenicity of Brucella as taxonomic feature, to determine their phylogenetic relation to other microorganisms by their bacteriocinogenic properties and to investigate the physicochemical properties of brucellacin and conditions for its stable detection. The Brucella cultures were isolated in the Caucasus. Investigation of their capacity for production of bacteriocin according to the procedure described by M.A. Konstantinova and A.D. Garmazova (1979) revealed that 62.1 per cent of the 216 cultures tested produced brucellacin. Isolation of bacteriocin with the methods developed was shown possible in all of the tested strains of B. melitensis, B. abortus, B. suis and in most of the strains of B. ovis. The methods also provided an increase in the synthesis and activity of brucellacin. The analysis of the characteristic features of bacteriocinogenicity and the properties of bacteriocin allowed recommending the use of additional taxonomic features for identification and differentiation of Brucella. Sensitivity of the indicator strains of Brucella to bacteriocins of other species (F. tularensis, Campylobacter fetus intestinalis B-8833, Y. enterocolitica, Vibrio cholerae and E. coli Fredericq) was noted which was additional evidence of the phylogenic relation between the above organisms. Investigation of the physicochemical properties of brucellacin confirmed the suggestion of the protein nature of the active principle of brucellacin and its similarity in different Brucella species.     

Isolation of the fibrinogen-binding region of platelet thrombospondin

Purified platelet thrombospondin binds to immobilized fibrinogen if both Ca++ and Mg++ are present. Digestion of the purified molecule with thermolysin results in a limited number of discrete proteolytic fragments. When such digests are subjected to affinity chromatography on immobilized fibrinogen, only the fragments with Mr of 120,000 and 140,000 are specifically bound and subsequently eluted by the addition of EDTA to the column buffer. Examination by SDS-PAGE under both reducing and nonreducing conditions reveals that the fibrinogen-binding domain is derived from the region of the thrombospondin molecule containing the interchain disulfide bonds. The requirement for Ca++ and Mg++ for optimal binding to fibrinogen is also manifest by the Mr 120,000/140,000 thermolytic fragments.     

Effects of polyamines on the first division cycle of Xenopus laevis eggs

The involvement of polyamines in cytokinesis has been examined in eggs of the amphibian X. laevis. Microinjection of spermine or spermidine into unfertilized eggs induced a shortening of the first division cycle and early formation of cleavage-like constrictions. Eggs were activated by injection and developed furrows about 45 min later, whereas the first division normally occurred around 120 min after activation. In terms of concentration, spermine was slightly more effective than spermidine, but putrescine had no influence on the division cycle.     

Transformation of Neurospora crassa with recombinant plasmids containing the cloned glutamate dehydrogenase (am) gene: evidence for autonomous replication of the transforming plasmid.

We have characterized Neurospora crassa transformants obtained with plasmid pJR2, which consists of the Neurospora glutamate dehydrogenase (am) gene cloned in pUC8 and an am132 host strain which contains a deletion encompassing the cloned fragment. Every one of 33 transformants tested showed extreme meiotic instability: less than 1 or 2% am+ progeny were obtained in initial or successive backcrosses between am+ transformants and am132 or in intercrosses between am+ progeny. Furthermore, am+ progeny from backcrosses gave a high proportion of auxotrophic (am) mitotic segregants during vegetative growth. These results indicate that the am+ character is not stably integrated into chromosomal DNA in any of the transformants tested. Nuclear DNAs from six transformants were analyzed by Southern hybridization. All six transformants contained sequences homologous to pJR2. Four showed restriction fragments expected for unmodified pJR2, but most showed additional bands. Southern blots of undigested DNAs showed that the plasmid sequences are present predominantly in high-molecular-weight form (larger than 20 kilobases). Southern blots showed that auxotrophic (am) progeny from a backcross to am132 had lost restriction bands corresponding to free plasmid but retained additional bands, apparently integrated into chromosomal DNA in a nonfunctional manner. Considered together, these results are most reasonably interpreted as follows: recombinant plasmids containing the am+ gene can replicate autonomously in N. crassa, the free plasmids are present in oligomeric or modified form or both, and plasmid sequences also integrate at multiple sites in the deletion host but in a nonfunctional manner. An alternate interpretation--that tandem repeats of the plasmid are integrated into chromosomal DNA but eliminated during meiosis--cannot be completely excluded. However, stable integration of the am gene can be obtained under a variety of other conditions, viz., using the am gene cloned in a phage lambda vector (J. A. Kinsey and J. A. Rambosek, Mol. Cell. Biol. 4:117-122, 1984), using derivatives of pJR2, or using pJR2 to transform a frameshift mutant.     

Plant regeneration from cotyledonary tissue of Glycine canescens,a perennial wild relative of soybean

Cotyledonary tissue from immature embryos of Glycine canescens was induced to callus and then form embryo-like structures. These structures could be cultured into whole plants and grown in soil.     

Changes in cell-wall polysaccharides in relation to seedling development and the mobilisation of reserves in the cotyledons of Lupinus angustifolius cv. Unicrop

Some 22% of the dry weight of the cotyledons of resting seeds of Lupinus angustifolius cv. Unicrop has been shown to be non-starch polysaccharide material comprising the massively thickened walls of the storage mesophyll cells. On hydrolysis this material released galactose (76%), arabinose (13%), xylose (4%), uronic acid (7%): only traces of glucose were detected indicating the virtual absence of cellulose from the walls. Changes in the amount and composition of this material following germination have been studied in relation to parameters of seedling development and the mobilisation of protein, lipid and oligosaccharide reserves. Starch, which was not present in the resting seed, appeared transitorily following germination: under conditions of continuous darkness starch levels were reduced. During the period of bulk-reserve mobilisation, 92% of the non-starch polysaccharide material disappeared from the cotyledons. The residual cell-wall material released galactose (14%), arabinose (19%), xylose (24%) and uronic acid (43%). The galactose and arabinose residues of the cotyledonary cell walls clearly constitute a major storage material, quantitatively as important as protein. The overall role of the wall polysaccharides in seedling development is discussed.     

Selected aspects of collared peccary (Dicotyles tajacu) reproductive biology in a captive texas herd

Collared peccaries (Dicotyles tajacu) from 32 litters were born in captivity during the period from September, 1981 through July, 1983. Incidence of singleton, twin, and triplet litters was 28%, 66%, and 6%, respectively. Mean (± SE) weight of young from singleton, twin, and triplet litters was 751 (± 35) gm, 698 (± 17) gm, and 612 (± 74) gm, respectively. Sex ratio among all litters was 56:44 (M:F). Neonatal mortality amounted to 9% of the young born. Mean duration of estrus was 2.60 days and mean length of gestation was 145.6 days. Evidence indicated that multiple copulations increased ovulation rate and the chance for conception.