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PubMed2005

Assessment of the genetic diversity and phylogenetic relationships of a temperate bamboo collection by using transferred EST-SSR markers.

Polymorphic expressed sequence tag - simple sequence repeat (EST-SSR) markers derived from major cereal crops were used to assess the genetic diversity of the USDA temperate bamboo collection consisting of 92 accessions classified in 11 separate genera and 44 species. A total of 211 bands were detected with a mean number of alleles per locus of 8.440. Phylogenetic relationships were determined by calculating genetic distances between all pairwise combinations and assessing differences in character data. The resulting dendrograms (unweighted pair group method with arithmetic means (UPGMA) and parsimony) clustered the accessions into 2 main clades, which corresponded to accessions characterized morphologically as either clumping (sympodial) or running (monopodial) bamboos. The majority of the accessions clustered according to their current taxonomic classification. These markers were also beneficial in identifying contaminated and (or) misidentified plots. Overall, these transferred markers were informative in differentiating the various bamboo accessions and determining the level of genetic variation within and among species and genera.

Alleles↗
PubMed1975

The isolation and characterization of a temperate phage, Y46/(E2), from Erwinia herbicola Y40.

A temperate phage was induced from exponential phase cells of Erwinia herbicola Y46 by treatment with mitomycin C. The phage was purified by single plaque isolation, and produced in bulk by successive cultivation in young cultures of E. herbicola Y 178. Phages were concentrated from culture filtrates by rate zonal centrifugation and resuspension in 0.02 M Tris buffer, pH 7.2, twice, yielding suspensions of about 5 times 10(11) PFU/ml. Purification was achieved by centrifugation in buffered sucrose solutions. The band at the 30/40% sucrose interface yielded intact particles having regular hexagonal heads and lonb contractile tails, with base plates. Fibers were not seen. The mean dimensions were head, 51 nm; neck length, 11 nm; overall tail length, extended, 98 nm and contracted, 75 nm; diameter of tail sheath, 24 nm. The phage was stable from pH 4.0 to 11.0, but unstable at pH 3.0, the response being independent of the suspending medium used. At pH 3.0, a survival curve having biphasic appearance was observed, which was not due to a mixed population of phages. Stability to heat was good up to 45 degrees C, above which a logarithmic decline with temperature increase occurred. The average inactivation rate constant at 50 degrees C and pH 6.8 was 0.15 min-1. Adsorption to E. herbicola Y 178 cells exhibited first-order kinetics, the adsorption rate constant being 2.5 times 10(-10) ml/min. One-step growth-curve experiments indicated a burst size of 35-40, and a minimum latent period of 80 min. Probit analysis gave a mean latent period of 140 min (SD 25). The phage caused lysis of only E. herbicola strains Y178 and Y186.

Adsorption↗
PubMed1976

Temperate phages of Clostridium perfringens type C1.

Four phages isolated from carrier strains of Clostridium perfringens type C belong to two classes. The three phages of class I, c1, c3, and c4, and homoimmune and serologically closely related. The phage of class II, c5, is heteroimmune to the class I phages and not related to them serologically. Transduction experiments with several of the phages were negative. Mutants of the indicator strain with surface alterations occurred spontaneously in stock cultures. Electron micrographs show the phages of each class to be distinct yet similar, having polyhedral heads of about the same diameter 55 nm, and long, flexible tails without sheaths or collars. Phages c4 and c5 were characterized for their lysogenic properties. Phage c4 was inducible with mitomycin C. Both c4 and c5 were temperate viruses by the test of stability of their respective lysogens to phage-specific antisera.

Antigens, Viral↗
PubMed1979

The role of temperate bacteriophage SP beta in prophage-mediated interference in Bacillus subtilis.

Virulent bacteriophage phi 1 grows on a variety of Bacillus subtilis strains, mutants of this virus which abortively infect the transformable bacillus. B. subtilis 168, while retaining the ability to productively infect related bacteria have been found. In the present study, we demonstrate that the inability of one such variant, phi 1m, to develop normally in strain 168 is mediated by cryptic prophage SP beta. The latter is a temperate bacteriophage which is carried by B. subtilis 168 and most strains derived from this bacterium. Phi 1 m infection of SP beta lysogens begins with apparently normal adsorption, penetration, and inititaion of virus-directed syntheses. At about the 20th min of the latent period, however, there is an abrupt cessation of nucleic acid synthesis and cellular respiration, accompanied by a change in cell permeability. This course of events can be altered to a permissive infection by mutation in the mpi gene of SP beta, by mutation in the spoOA gene of the host, or by growing SP beta lysogens at high temperature. In addition, we found a second class of phi 1 mutants which abortively infect B. subtilis 168 derivatives even in the absence of the SP beta prophage.

Bacillus subtilis↗
PubMed1981

A new temperate phage of streptomyces venezuelae: morphology, DNA molecular weight and host range of SV2.

A new, narrow host range temperate phage, SV2, was isolated from soil. It lysogenized and lysed strains of Streptomyces venezuelae and seemed to be specific for this species. In general morphology, the virions were typically lambdoid, but had unusually ringed tails similar to those of some rare phages isolated from hosts belonging to different bacterial genera. The molecular weight of double-stranded linear SV2 DNA, estimated at about 24 X 10(6), was lower than the published values for other Streptomyces phages.

Bacteriophages↗
PubMed1981

Effect of inoculation of Zea mays with Azospirillum brasilense strains under temperate conditions.

Seven strains of Azospirillum brasilense were compared for their effect on the growth of Zea mays grown under temperate conditions in sand--vermiculite pot cultures. Inoculation with all seven strains tested, including Fix(-) mutant strains, increased dry weight and total nitrogen content of shoots, but nitrogen concentrations were unaffected. Low and variable rates of acetylene reduction activity were observed from excised roots of inoculated plants without preincubation. Estimates of N2-fixing A. brasilense associated with inoculated roots showed differences between strains in establishing themselves in the rhizosphere and endorhizosphere. In some strains enrichment in the endorhizosphere of roots occurred following inoculation, but the relative numbers and location of the strains did not appear to affect the yield response.

Acetylene↗
PubMed1997

Isolation and characterization of promoters from the Lactobacillus casei temperate bacteriophage A2.

Random Sau3A1 DNA fragments from the temperate Lactobacillus bacteriophage A2 were cloned into the promoter-probe plasmid pGKV210. Seven DNA fragments with promoter activity were selected, after transformation of Escherichia coli and Lactococcus lactis, subsp, lactis, through the chloramphenicol resistance they conferred to the corresponding clones. The seven promoters were functional in Lactobacillus casei. Their strength was analysed by measuring the levels of chloramphenicol resistance and chloramphenicol acetyltransferase activity induced in each host. The nucleotide sequences of these fragments were determined and primer extension analysis was used to locate the initiation site of transcription from each promoter in E coli. The promoters contained -10 and -35 regions similar to the consensus sequences of E. coli and Lactobacillus promoters.

Bacteriophages↗
PubMed1999

Family values in the age of genomics: comparative analyses of temperate bacteriophage HK022.

HK022 is a temperate coliphage related to phage lambda. Its chromosome has been completely sequenced, and several aspects of its life cycle have been intensively studied. In the overall arrangement, expression, and function of most of its genes, HK022 broadly resembles lambda and other members of the lambda family. Upon closer view, significant differences emerge. The differences reveal alternative strategies used by related phages to cope with similar problems and illuminate previously unknown regulatory and structural motifs. HK022 prophages protect lysogens from superinfection by producing a sequence-specific RNA binding protein that prematurely terminates nascent transcripts of infecting phage. It uses a novel RNA-based mechanism to antiterminate its own early transcription. The HK022 protein shell is strengthened by a complex pattern of covalent subunit interlinking to form a unitary structure that resembles chain-mail armour. Its integrase and repressor proteins are similar to those of lambda, but the differences provide insights into the evolution of biological specificity and the elements needed for construction of a stable genetic switch.

Bacteriophage lambda↗
PubMed1998

High-energy turnover at low temperatures: recovery from exhaustive exercise in Antarctic and temperate eelpouts.

Earlier work on Notothenioids led to the hypothesis that a reduced glycolytic capacity is a general adaptation to low temperatures in Antarctic fish. In our study this hypothesis was reinvestigated by comparing changes in the metabolic status of the white musculature in two related zoarcid species, the stenothermal Antarctic eelpout Pachycara brachycephalum and the eurythermal Zoarces viviparus during exercise and subsequent recovery at 0 degreesC. In both species, strenuous exercise caused a similar increase in white muscle lactate, a drop in intracellular pH (pHi) by about 0.5 pH units, and a 90% depletion of phosphocreatine. This is the first study on Antarctic fish that shows an increase in white muscle lactate concentrations. Thus the hypothesis that a reduced importance of the glycolytic pathway is characteristic for cold-adapted polar fish cannot hold. The recovery process, especially the clearance of white muscle lactate, is significantly faster in the Antarctic than in temperate eelpout. Based on metabolite data, we calculated that during the first hour of recovery aerobic metabolism is increased 6.6-fold compared with resting rates in P. brachycephalum vs. an only 2.9-fold increase in Z. viviparus. This strong stimulation of aerobic metabolism despite low temperatures may be caused by a pronounced increase of free ADP levels, in the context of higher levels of pHi and ATP, which is observed in the Antarctic species. Although basal metabolic rates are identical in both species, the comparison of metabolic rates during situations of high-energy turnover reveals that the stenothermal P. brachycephalum shows a higher degree of metabolic cold compensation than the eurythermal Z. viviparus. Muscular fatigue after escape swimming may be caused by a drop of the free energy change of ATP hydrolysis, which is shown to fall below critical levels for cellular ATPases in exhausted animals of both species.

Adenosine Diphosphate↗
PubMed1999

Temperature-dependent expression of cytochrome-c oxidase in Antarctic and temperate fish.

Seasonal acclimation versus permanent adaptation to low temperatures leads to a differential response in the expression of cytochrome-c oxidase (CCO) in temperate and Antarctic eelpouts. Although eurythermal eelpout from the North Sea (Zoarces viviparus) displayed a cold-induced rise of CCO activity in white muscle, enzyme activity in the cold stenothermal Antarctic eelpout Pachycara brachycephalum failed to reflect such a compensatory increase. In Antarctic eelpout, CCO activity correlates with transcript levels of mitochondrial encoded subunits of CCO (CCO I and CCO II), whereas cold-acclimated eelpout from the North Sea show lower enzyme activities than expected on the basis of mitochondrial mRNA levels. In these animals, CCO expression at low temperatures may be limited either by nuclear CCO transcripts or by posttranscriptional processes. These may comprise translation of the subunits or assembly of the CCO holoenzyme. mRNA levels of CCO IV, one of the nuclear encoded subunits, increased strongly during cold acclimation, indicating that the expression of CCO is likely not message limited in cold-acclimated Z. viviparus. Our data suggest that seasonal cold acclimation of Z. viviparus results in a modification of the relationship between transcription and translation or posttranslational processes. In permanently cold-adapted P. brachycephalum, on the other hand, CCO expression shows similar characteristics as in the warm-acclimated confamilial species, e.g., low levels of enzyme activity correlated with low levels of mitochondrial message.

Acclimatization↗
PubMed1998

Influence of thermal stress on the incidence of acute myocardial infarction in a temperate climate.

Using a Poisson regression model the relative incidence of acute myocardial infarctions (AMI) prospectively registered in 8 hospitals within a radius of 50 km during a 2-year period was correlated with the outside conditions characterized by a complete thermophysiological model (Klima-Michel Model) defining thermal stress. An increase in the incidence of AMI related to thermal stress could be demonstrated neither by splitting the study period into 12 equally sized 'felt-temperature' classes by months of the year nor by single days. This was confirmed by correlation of the AMI rate with the mean felt-temperature level during the preceding 14 days. Thermal stress caused by the atmospheric conditions in a temperate climate may be too weak to influence significantly the incidence of AMI.

Aged↗
PubMed2004

B chromosomes in hybrids of temperate cereals and grasses.

B chromosomes are considered to be genetically inert, yet often have pronounced and surprising effects upon the A chromosome behaviour at meiosis in inter-generic and inter-specific hybrids. We review here our current knowledge of these effects in a number of different hybrids of the temperate cereals and grasses. Through hybridisation, many effects comparable to the pairing control system of wheat are uncovered, together with complex interactions of B chromosomes with hybrid host genotypes. We discuss the genetic and physical basis of the effects and try to make sense of them in terms of what we know about the origin and evolution of B chromosomes in plants.

Chimera↗
PubMed1976

[Cervico-facial lesions caused by windshields of tempered glass].

The authors stress the dangers presented by windshield fragments of tempered glass to soft parts of the cervicofacial region, in cases of traffic accidents. With the aid of seven recent clinical observations, the difficulties in emergency surgical treatment, late complications due to the persistence of foreign bodies, and permanent facial mutilations are successively discussed.

Accidents, Traffic↗
PubMed1976

Temperate season outdoor housing of Saimiri sciureus in the northern United States.

This study demonstrates the ability of Saimiri to adapt to out-of-door housing in a northern temperate climate from May through October, to ovulate (both naturally and in response to an induction regime), become pregnant, give birth, and to initiate lactation. The observations reported are of importance for the captive breeding of Saimiri for use in biomedical research.

Abortion, Veterinary↗
PubMed1989

Tempering stresses in feldspathic porcelain.

The objective of this study was to develop an analytical model to calculate transient and residual (tempering) stresses in dental porcelain plates subjected to cooling rates used by commercial laboratories. The model incorporates linear viscoelasticity and structural relaxation effects. The viscosities of three experimental body porcelains and three experimental opaque porcelains as a function of temperature were calculated from creep rates measured in a bending beam viscometer. Measurements were made under thermal equilibrium conditions for temperatures ranging from 550 degrees C to 625 degrees C. Thermal expansion data measured in a differential dilatometer at slow heating rates were supplied by the manufacturer. Temperature distribution in the plates as a function of convective heat transfer coefficient, initial plate temperature, and plate thickness was calculated by use of standard numerical techniques. Calculations of transient and residual stress were performed for one body porcelain, for two plate thicknesses, and for three variable cooling rates. Calculated surface residual stresses were strongly dependent on plate thickness, cooling rate, and initial soak temperature. For the cases studied, the maximum residual surface compressive stress was 26.4 MPa.

Chemical Phenomena↗
PubMed2003

Influences of thermal acclimation and acute temperature change on the motility of epithelial wound-healing cells (keratocytes) of tropical, temperate and Antarctic fish.

The ability to heal superficial wounds is an important element in an organism's repertoire of adaptive responses to environmental stress. In fish, motile cells termed keratocytes are thought to play important roles in the wound-healing process. Keratocyte motility, like other physiological rate processes, is likely to be dependent on temperature and to show adaptive variation among differently thermally adapted species. We have quantified the effects of acute temperature change and thermal acclimation on actin-based keratocyte movement in primary cultures of keratocytes from four species of teleost fish adapted to widely different thermal conditions: two eurythermal species, the longjaw mudsucker Gillichthys mirabilis (environmental temperature range of approximately 10-37 degrees C) and a desert pupfish, Cyprinodon salinus (10-40 degrees C), and two species from stable thermal environments, an Antarctic notothenioid, Trematomus bernacchii (-1.86 degrees C), and a tropical clownfish, Amphiprion percula (26-30 degrees C). For all species, keratocyte speed increased with increasing temperature. G. mirabilis and C. salinus keratocytes reached maximal speeds at 25 degrees C and 35 degrees C, respectively, temperatures within the species' normal thermal ranges. Keratocytes of the stenothermal species continued to increase in speed as temperature increased above the species' normal temperature ranges. The thermal limits of keratocyte motility appear to exceed those of whole-organism thermal tolerance, notably in the case of T. bernacchii. Keratocytes of T. bernacchii survived supercooling to -6 degrees C and retained motility at temperatures as high as 20 degrees C. Mean keratocyte speed was conserved at physiological temperatures for the three temperate and tropical species, which suggests that a certain rate of motility is advantageous for wound healing. However, there was no temperature compensation in speed of movement for keratocytes of the Antarctic fish, which have extremely slow rates of movement at physiological temperatures. Keratocytes from all species moved in a persistent, unidirectional manner at low temperatures but at higher temperatures began to take more circular or less-persistent paths. Thermal acclimation affected the persistence and turning magnitude of keratocytes, with warmer acclimations generally yielding more persistent cells that followed straighter paths. However, acclimation did not alter the effect of experimental temperature on cellular speed. These findings suggest that more than one temperature-sensitive mechanism may govern cell motility: the rate-limiting process(es) responsible for speed is distinct from the mechanism(s) underlying directionality and persistence. Keratocytes represent a useful study system for evaluating the effects of temperature at the cellular level and for studying adaptive variation in actin-based cellular movement and capacity for wound healing.

Acclimatization↗
PubMed1996

Magnetic orientation of snow buntings (Plectrophenax nivalis), a species breeding in the high Arctic: passage migration through temperate-zone areas

Orientation tests were conducted with snow buntings (Plectrophenax nivalis) exposed to artificially manipulated magnetic fields, during both spring and autumn migration. Experiments were run under clear sunset skies and under simulated complete overcast. The birds closely followed experimental shifts of the magnetic fields during both seasons regardless of whether they had access to celestial cues. Clear-sky tests in vertical magnetic fields resulted in a significant bimodal orientation, the directionality of which was almost identical during spring and autumn. When the snow buntings were deprived of celestial directional information and tested in vertical magnetic fields, they failed to show any statistically significant mean directions in either spring or autumn. The results demonstrate that snow buntings possess a magnetic compass and suggest that magnetic cues are of primary importance for their migratory orientation while on passage through temperate-zone areas. However, the axial orientation in vertical magnetic fields under clear skies may indicate an involvement of celestial cues as an auxiliary source of directional information.

Journal Article↗
PubMed1999

Physiological disturbances at critically high temperatures: a comparison between stenothermal antarctic and eurythermal temperate eelpouts (Zoarcidae)

The effect of gradually increased water temperature on the metabolism of temperate eelpout from the North Sea (Zoarces viviparus) and Antarctic eelpout (Pachycara brachycephalum) was investigated. Standard metabolic rate (SMR) was similar in cold-adapted P. brachycephalum and cold-acclimated Z. viviparus in the low temperature range. This indicates that Antarctic eelpout show no metabolic cold adaptation (as originally defined by Wohlschlag); however, they do show a compensatory increase of oxygen consumption compared to warm-acclimated eelpout. SMR increased more strongly with rising temperature in P. brachycephalum than in Z. viviparus, which is reflected in a higher Arrhenius activation energy for oxygen consumption (99+/-5 kJ mol(-)(1), versus 55+/-3 kJ mol(-)(1) for cold-acclimated Z. viviparus; means +/- s.d.). The intracellular pH in the white musculature of Z. viviparus follows alphastat regulation over the whole investigated temperature range and dropped at a rate of -0.016 pH units per degrees C between 3 degrees C and 24 degrees C. In Antarctic eelpout white muscle pH declined at a rate of -0.015 pH units per degrees C between 0 degrees C and 3 degrees C, but deviated from alphastat at higher temperatures, indicating that thermal stress leads to acid-base disturbances in this species. The upper critical temperature limit (Tc(II); characterised by a transition to anaerobic metabolism) was found to be between 21 degrees C and 24 degrees C for Z. viviparus and around 9 degrees C for P. brachycephalum. In both species a rise of succinate concentration in the liver tissue turned out to be the most useful indicator of Tc(II). Obviously, liver is more sensitive to heat stress than is white muscle. Accordingly, the energy status of white muscle is not diminished at Tc(II). Heat-induced hyperglycaemia was observed in Antarctic eelpout (at 9 degrees C and 10 degrees C), but not in common eelpout. Based on our results and on literature data, impaired respiration in combination with circulatory failure is suggested as the final cause of heat death. Our data suggest that the southern distribution limit of Zoarces viviparus is correlated with the limit of thermal tolerance. Therefore, it can be anticipated that global warming would cause a shift in the distribution of this species.

Journal Article↗