Semiquantitative Oropharyngeal Culture Technique

A semiquantitative method for determining the concentration of organisms constituting the normal oropharyngeal flora has been developed. Eleven species of organisms were isolated from the 18 subjects studied. The concentration of organisms in multiple samples, taken at 5-min intervals, was quite similar. The concentration of organisms increased slightly at the end of the day. Obtaining specimens on different days of the week did not appreciably affect the concentration or kinds of organisms. Eating had only a minimal effect on the oropharyngeal flora, but brushing teeth reduced the concentration of organisms substantially. When specimens were obtained 6 months after the initial specimens, the concentration of organisms remained the same but the species of organisms isolated varied considerably. The gargle method was compared to a swab method and proved to be superior. This method of obtaining oropharyngeal culture specimens is reliable and useful as a means of monitoring the normal oropharyngeal flora.     

Biological traits interact with human threats to drive extinctions: A modelling study

How a particular threat influences extinction risk may depend on biological traits. Empirical studies relating threats and traits are needed, but data are scarce, making simulations useful. We implemented an eco-evolutionary model to analyse how five threat types influence the extinction risk of virtual organisms differing in body size, maturity age, fecundity, and dispersal ability. The model consisted of observing the evolutionary shift in the mean trait values of an assemblage of organisms when a threat was added into the virtual world where they lived. If a positive shift was found in trait values, we considered that the threat negatively influenced organisms with lower values for that trait. Direct killing mostly affected organisms with slow life cycles (slower-living) and poorly dispersive organisms. Habitat loss caused a reduction in the average dispersal ability of organisms. Habitat fragmentation caused an increase of average dispersal ability, and had a negative effect on larger, less fecund organisms. Habitat degradation and the introduction of invasive competitors had similar effects, mostly affecting large and fast-living organisms, with habitat degradation also affecting highly fecund and poorly dispersive organisms. These results agree with previous empirical studies in which larger, slower-lived, and less fecund organisms are more vulnerable to a greater range of threats. On the other hand, our results challenge two commonly seen hypotheses in the literature: that organisms with high dispersal ability fare well under any high habitat loss scenarios, and that fast-living, highly fecund organisms always do well during environmental change. Our study shows that highly dispersive organisms may be the losers when habitat loss removes large continuous areas of habitat, and fast-living and highly reproductive organisms may be the losers when resources or energy availability dwindle to very low levels. Most importantly, our study underpins the importance of considering the type of threat when analysing the relation between traits and extinction. Even in simple scenarios such as the ones modelled here, different threats lead to different, sometimes opposite, extinction probabilities according to the biological traits of organisms.     

Multiple, Novel Biologically Active Endophytic Actinomycetes Isolated from Upper Amazonian Rainforests

Microbial biodiversity provides an increasingly important source of medically and industrially useful compounds. We have isolated 14 actinomycete species from a collection of approximately 300 plant stem samples from the upper Amazonian rainforest in Peru. All of the cultured isolates produce substances with inhibitory activity directed at a range of potential fungal and bacterial pathogens. For some organisms, this activity is very broad in spectrum while other organisms show specific activity against a limited number of organisms. Two of these organisms preferentially inhibit bacterial test organisms over eukaryotic organisms. rDNA sequence analysis indicates that these organisms are not equivalent to any other cultured deposits in GenBank. Our results provide evidence of the untapped biodiversity in the form of biologically active microbes present within the tissues of higher plants.     

Bacteremia in Experimental Tyzzer's Disease of Mice

Bacteremia was observed during the late stage of experimental Tyzzer's disease in mice. The number of organisms in the blood in mice treated with cortisone increased markedly in the infection with highly virulent organisms, whereas bacteremia was of low incidence and less severe in infections with low virulence organisms. The number of organisms in the blood stream was shown to increase linearly during the course of fatal infection attaining a maximum level of 10⁷ organisms per ml blood. The number of organisms in the blood was found to be closely related to the number in the liver when bacteremia was observed. In the peripheral blood, organisms were first detectable when the number of organisms in the liver gained a level of 10⁷ per g tissue, and the subsequent increase in the number of bacteria in the blood was approximately 3 times more rapid than in the liver. The organisms in the blood were comparable to those in the liver morphologically as well as in pathogenicity. Histopathological examination frequently revealed liberation of organisms from liver cells into sinusoids. There was no evidence of significant multiplication of the organisms in organs other than the liver.     

The other mediator for adherence of Haemophilus influenzae organisms without involvement of fimbriae.

The number of the nontypeable Haemophilus influenzae (HiN) organisms that adhered to the primary mouse fetal lung cells was significantly more than type b Haemophilus influenzae (Hib) organisms. The average number of HiN organisms adherent to host cells was 2,291/100 host cells (range, 1,654-3,182), but that of Hib was markedly reduced to 147/100 host cells (range, 102-238). In this case, P value was less than 0.05 by using a paired Student t-test. The sonicated extract from HiN TMS11 organisms inhibited adherence of H. influenzae TMS11 organisms to monolayer at 76.3% and it inhibited adherence of Hib TMS24 organisms at 92.3%. This result indicates that a mediator existing on the surface of HiN organisms may be the same as that on type b organisms. The number of detected organisms in broncho and lung tissues 3 days after intranasal infection with HiN strains was significantly greater than that in infection with Hib strains. Therefore, in vitro adhesive capacity of H. influenzae organisms was correlative to infectivity by intranasal injection.     

DNA and the theory of stabilizing selection

A comparison of structural-functional features of genomic DNAs allowed to estimate the role of internal and external factors in evolution of different groups of organisms. The basic difference between higher and lower organisms has been demonstrated. It is reflected in the difference of their reaction on to external factors in accordance with two adaptation types, the openness and autonomization. There is a correlation between structural-functional organization of genomic DNAs of higher and lower organisms and the above mentioned types of adaptation. DNA of lower organisms has been proposed to be characterized as "labile", and that of higher organisms, as "stable". The "DNA lability" means high mutation ability, which characterizes the existence of and evolution of lower organisms (genetic inconstancy of the lower organisms). On the contrary, "DNA stability" means the creation of stable genetic apparatus, reduction of variability in higher organisms (genetic constancy of higher organisms). This suggests the existence of the two principal ways of evolution.     

Are certain life histories particularly prone to local extinction?

Using stochastic simulations and elasticity analysis, we show that there are inherent differences in the risk of extinction between life histories with different demographies. Which life history is the most vulnerable depends on which vital rate varies. When juvenile survival varies semelparous organisms with delayed reproduction are the most vulnerable ones, while a varying developmental rate puts a greater threat to semelparous organisms with rapid development. Iteroparous organisms are the most vulnerable ones when adult survival varies. Generally, we do not expect to observe organisms in nature having variation in vital rates that produce a high risk of extinction. Given the results here we therefore predict that iteroparous organisms should show low variation in adult survival. Moreover, we predict that semelparous organisms should show low variation in juvenile survival and low variation in developmental rate. The effect of temporal correlation on extinction risk is most pronounced in organisms with semelparous life histories.     

Programmed cell death in trypanosomatids and other unicellular organisms

In multicellular organisms, cellular growth and development can be controlled by programmed cell death (PCD), which is defined by a sequence of regulated events. However, PCD is thought to have evolved not only to regulate growth and development in multicellular organisms but also to have a functional role in the biology of unicellular organisms. In protozoan parasites and in other unicellular organisms, features of PCD similar to those in multicellular organisms have been reported, suggesting some commonality in the PCD pathway between unicellular and multicellular organisms. However, more extensive studies are needed to fully characterise the PCD pathway and to define the factors that control PCD in the unicellular organisms. The understanding of the PCD pathway in unicellular organisms could delineate the evolutionary origin of this pathway. Further characterisation of the PCD pathway in the unicellular parasites could provide information regarding their pathogenesis, which could be exploited to target new drugs to limit their growth and treat the disease they cause.     

Organism size promotes the evolution of specialized cells in multicellular digital organisms

Specialized cells are the essence of complex multicellular life. Fossils allow us to study the modification of specialized, multicellular features such as jaws, scales, and muscular appendages. But it is still unclear what organismal properties contributed to the transition from undifferentiated organisms, which contain only a single cell type, to multicellular organisms with specialized cells. Using digital organisms I studied this transition. My simulations show that the transition to specialized cells happens faster in organism composed of many cells than in organisms composed of few cells. Large organisms suffer less from temporarily unsuccessful evolutionary experiments with individual cells, allowing them to evolve specialized cells via evolutionary trajectories that are unavailable to smaller organisms. This demonstrates that the evolution of simple multicellular organisms which are composed of many functionally identical cells accelerates the evolution of more complex organisms with specialized cells.     

玉米和花生根际生物的原位观察初探*

利用改进根箱法对玉米和花生根际生物进行了原位采样和观察。采用载玻片贴片方法直接采集到作物根系分泌物中的生物,并用荧光显微镜进行观察。花生根系分泌物中分布有微生物,但是根系表面未发现生物;玉米根系分泌物中分布有线虫和生物体,根系表面分布有生物体,其形态与根系分泌物中生物体形态相似。表明此方法是一种原位研究根际生物的较为有效的方法。     

Tables of dose conversion coefficients for estimating internal and external radiation exposures to terrestrial and aquatic biota

Dose conversion coefficients (DCCs) for assessment of internal and external radiation exposures to terrestrial and aquatic biota are compiled for 75 radionuclides, for 14 terrestrial and 22 aquatic reference organisms. DCC values for internal exposure are calculated based on a homogeneous distribution of the radionuclides in both types of organisms. DCC values for external exposure of aquatic organisms are calculated for complete immersion in water. For external exposure of terrestrial organisms the soil is considered as a planar and homogenously contaminated volume source with a surface roughness of 3 mm and a thickness of 10 cm, respectively. For in-soil-organisms, DCC values for external exposure are given assuming that these organisms live in the middle of a uniformly contaminated 50 cm-thick soil layer. The tables can be used for assessment of exposures of animals and plants living in various habitats. The list of considered organisms covers the Reference Animals and Plants as adopted by the ICRP.     

DNA analysis of intracellular campylobacter-like organisms associated with the porcine proliferative enteropathies: novel organism proposed

Intracellular Campylobacter-like organisms are a consistent feature of the porcine proliferative enteropathies. The relationship between these organisms and known Campylobacter sp. previously associated with the disease was studied using restriction enzyme analysis and DNA-DNA blot hybridization techniques. BglII restriction enzyme fragment patterns of DNA of the Campylobacter-like organisms were fundamentally different from those of C. mucosalis, C. hyointestnalis, C. jejuni, and C. coli. Crude DNA preparations from Campylobacter-like organisms hybridized strongly with homologous preparations, weakly with porcine DNA and not at all with DNA from Campylobacter sp. Fragment specific DNA probes prepared from Campylobacter-like organisms only hybridized with homologous preparations. This work suggests that the intracellular Campylobacter-like organisms are not one of the known Campylobacter sp. It is possible that they are a novel, uncultured organism worthy of a new name, such as HC. intracellulare'.     

Screening of fungal strains employed in the testing of plastics materials

The problems of selecting tests method and suitable challenge organisms for plastics materials are discussed. Enzyme activities of fungal strains employed in the testing of plastics have been investigated and compared with isolates of these organisms held elsewhere. The ability of organisms to clear a polycaprolactone diol medium has been assessed semiquantitatively and the results discussed in relation to the selection of organisms.     

Cost of resistance to parasites in digital organisms

Virtually all organisms are attacked by parasites and are therefore expected to evolve resistance against these natural enemies. Parasite resistance is costly in a wide range of organisms, although the generality of such costs has been questioned, especially when resistance is not based on reallocation of resources. Digital organisms are increasingly used to explore aspects of life in general. In the Tierra system, there is a trade-off between resistance against parasites and competitive ability. Because digital organisms are too simple to store resources, the finding that resistance to parasites is costly in digital organisms suggests that costs of parasite resistance can also occur when resistance is not resource based.     

Cell biology of deep-sea multicellular organisms

Establishing tissue cultures derived from deep-sea multicellular organisms has been extremely difficult because of the serious damage they sustain upon decompression and exposure to the high temperature of surface seawater. We developed a novel pressure-stat aquarium system for the study of living deep-sea multicellular organisms under pressure. Using this system, we have succeeded in maintaining a variety of deep-sea multicellular organisms under pressure and atmospheric conditions after gradual, slow decompression. Furthermore, we successfully cultivated and freeze-stocked pectoral fin cells of the deep-sea eel Simenchelys parasiticus collected at a depth of 1,162 m under atmospheric pressure conditions. This review describes novel capture and maintenance devices for deep-sea organisms and cell culture studies of the organisms under atmospheric and pressure conditions.     

Passage of Treponema pallidum Through Membrane Filters of Various Pore Sizes

The passage of Treponema pallidum through commercially available Millipore membrane filters of various pore sizes was examined. No microscopically detectable organisms passed through a filter with a pore diameter of 0.22 mum. As pore size was increased, progressively more organisms passed through. Motile organisms passed through filters to a greater extent than nonmotile ones; however, 22% of the motile and 50% of the nonmotile T. pallidum organisms did not pass through the largest pore diameter tested (14.0 mum). Filtration of T. pallidum suspensions through membrane filters may offer a way of separating the organisms from larger particles of debris which accompany their extraction from rabbit testicular syphilomas.     

Initial phase of infection with Tyzzer's organism in cultured mouse hepatocytes

The initial phase of infection with Tyzzer's organisms in cultured mouse hepatocytes was observed using indirect immunofluorescence (IF) and a plaque assay. The organisms adhered poorly to aldehyde- or acetone-fixed cells, but once adhered to host cells, whether methanol-fixed or unfixed, they were not removed by methanol or acetone. By the IF as well as the plaque assay, both of which discriminated intra- and extracellularly located organisms, the number of cell-associated organisms increased linearly up to 3 h post-inoculation. The number of intra-cellular organisms increased rapidly in the first 1 h, followed by linear increase at a much lower rate. Similar results were obtained by the plaque assay.     

The choice of model organisms in evo-devo

Study of the model organisms of developmental biology was crucial in establishing evo-devo as a new discipline. However, it has been claimed that this limited sample of organisms paints a biased picture of the role of development in evolution. Consequently, judicious choice of new model organisms is necessary to provide a more balanced picture. The challenge is to determine the best criteria for choosing new model organisms, given limited resources.     

On the mechanisms involved in biological heme crystallization

Blood-feeding organisms digest hemoglobin, releasing large quantities of heme inside their digestive tracts. Free heme is very toxic, and these organisms have evolved several mechanisms to protect against its deleterious effects. One of these adaptations is the crystallization of heme into the dark-brown pigment hemozoin (Hz). Here we review the process of Hz formation, focusing on organisms other than Plasmodium that have contributed to a better understanding of heme crystallization. Hemozoin has been found in several distinct classes of organisms including protozoa, helminths and insects and Hz formation is the predominant form of heme detoxification. The available evidence indicates that amphiphilic structures such as phospholipid membranes and lipid droplets accompanied by specific proteins play a major role in heme crystallization. Because this process is specific to a number of blood-feeding organisms and absent in their hosts, Hz formation is an attractive target for the development of novel drugs to control illnesses associated with these hematophagous organisms.