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PubMed1991

Contribution of the VH11 gene family to mitogen-responsive B cell repertoire in C57BL/6 mice.

The contribution of VH11 gene family to the development of the primary B cell repertoire has been studied by analyzing 1.8 x 10(4) mitogen induced B lymphocyte colonies. The data demonstrate that VH11 family is predominantly expressed among neonatal splenic as well as adult peritoneal B cell colonies, both rich in Ly-1+ B cells. VH11 gene family expression among B splenocytes decreases during ontogeny and VH11 family pairs stochastically with different V kappa families among mitogen-activated neonatal B cell colonies, which are representative of an antigen unselected B cell repertoire. Thus, an increased VH11 expression among peritoneal and neonatal B cells points towards its biased expression among Ly-1+ B lymphocytes. The restricted V gene rearrangements and VH11-V kappa 9 pairing observed among anti-bromelain-treated mouse red blood cells autoantibodies are likely to be an outcome of both intrinsic gene recombination processes per se as well as selection by an autoantigen and/or local selective environmental factors.

Age Factors↗

PubMed2001

On mental events, disciplinary boundaries, and reductionism: a reply to Plaud.

Plaud's (2001) radical behavioral manifesto suggests that a psychological science based exclusively upon the study of environment-behavior functional contingencies would yield a discipline unencumbered by mentalism, vaguely delineated disciplinary boundaries, or inappropriate reductionism. In reply, we note that: (a) mental events-e.g., thoughts and feelings-are increasingly accessible to objective investigation, and provide an observable proximal causal mechanism for the environmental selection of behavior; (b) the call for pristine disciplinary boundaries is anachronistic, inasmuch as progress in the natural sciences has engendered disciplinary boundaries that are increasingly porous; (c) cognitive neuroscience facilitates a comprehensive understanding of complex human behavior by mapping out the relationship between such behavior and underlying brain events, thereby engaging in an appropriate form of reductionism (constitutive reductionism) that has become a hallmark of the natural sciences; and (d) ironically, it is radical behaviorism, in its disavowal of the informational level of complexity instantiated in brain events, that engages in inappropriate eliminative reductionism (i.e., reducing neural information to "nothing but" its underlying bring states).

Behaviorism↗

PubMed1999

Polyphyly and convergent morphological evolution in Commelinales and Commelinidae: evidence from rbcL sequence data.

Phylogenetic relationships of the five families of the order Commelinales remain an area of deep uncertainty in higher-level monocot systematics, despite intensive morphological and anatomical study. To test the monophyly of the Commelinales and the subclass Commelinidae, evaluate their relationships, and analyze evolutionary trends in their morphology, ecology, and biogeography, we conducted parsimony analyses on 95 rbcL sequences representing 17 taxa of Commelinales, 16 taxa of other Commelinidae, and 63 taxa from Arecidae, Liliidae, and Zingiberidae. Commelinales is polyphyletic and Commelinidae paraphyletic, with Eriocaulaceae and Xyridaceae sister to Poaceae and its relatives, Rapateaceae sister to Bromeliaceae and Mayacaceae, and Commelinaceae sister to Philydrales and allies. Thurnia is sister to Prionium at the base of Cyperaceae-Juncaceae; only 1 of Cronquist's multifamily commelinoid orders is diagnosed as monophyletic. We propose a revised Commelinidae, incorporating 4 revised superorders (Bromelianae, Commelinanae, Dasypogonanae, Arecanae) and 10 orders ((Poales, Eriocaulales, Cyperales, Typhales, Bromeliales), (Commelinales, Philydrales, Zingiberales), (Dasypogonales), (Arecales)). Morphological and anatomical characters used to define the original Commelinales and Commelinidae appear to be plesiomorphic or to reflect convergence or recurrent mutation; several characters supporting our revised classification are anatomical traits that seem relatively insulated from environmental selection pressures. The Commelinidae distal to the Arecales arose in South America, with amphiatlantic Bromeliaceae-Mayacaceae-Rapateaceae originating in the Guayana Shield. Ecological diversification involved the repeated invasion of shady, infertile, or arid microsites. The numbers of species in families of the revised Commelinidae are related partly to the extent of adaptive radiation in those families, but seem more strongly related to nonadaptive features promoting speciation, such as restricted seed dispersal (especially in forest interior groups with fleshy fruits), polyploidy, aneuploidy, and apomixis. Species diversity is unrelated to the rate/amount of rbcL sequence evolution.

DNA, Plant↗

PubMed1985

Polysubstrate monooxygenases in Drosophila, mammals and man.

There is overwhelming evidence that polysubstrate monooxygenases play a central role in the metabolism of endogenous compounds as well as in the biotransformation of xenobiotics. These enzyme systems are of great importance in such diverse fields as insecticide resistance, mutagenicity, carcinogenicity, drug metabolism, etc. The constitutive and, in particular, the induced forms represent various products from a multigene family. This has first been shown for the mouse, but evidence is accumulating that this is also true for other mammals and for man. Also in insects a similar picture is emerging. If the regulation of cytochrome P-450 induction resembles in any way the other methods by which prokaryotes and eukaryotes cope genetically with the many forms of environmental selective pressures, it is very likely that most organisms have the genetic capacity to produce not only hundreds but probably thousands of inducible forms of cytochrome P-450 (Nebert et al., 1981). Doubtless, many fields from pest control to cancer prevention to drug safety will profit from the elucidation of the genetic mechanisms involved.

Aflatoxin B1↗

PubMed1979

A dynamic system for long-term toxicity studies in fish under laboratory conditions.

For the evaluation of possible adverse effects of compounds in fish at sublethal doses a dynamic system is required. The design of such a system is presented including the methodology of performing long-term toxicity studies in fish using selected environmental chemicals (plant protection products). Chronic studies with Diazinon, Terburyn, Phosphamidon on carp and trout comprised 28 day treatment periods followed by 28-day recovery periods. In addition to the toxicity, the residues of the applied chemicals in fish, divided into muscle tissue and viscera, and in the test medium were determined during the experimental and recovery period. The results demostrate that the chemicals accumulated to a somewhat greater extent in the viscera than in the muscle tissue of the fish during exposure. In the course of the recovery period the concentration of the substances tested decreased to the limits of detection. It was concluded that following an adequate waiting period no measurable residues were formed from these plant protection products, that are carried in the food chain.

Animals↗

PubMed1981

Reactions to ischemic pain: interactions between individual, situational and naloxone effects.

Fifty-two paid volunteers participated in two separate factorial investigations of the effects of naloxone on time tolerance of and affective reactions to ischemia, as a function of the interaction between expectations of involvement in the experimental situation and experimental variables involving stress or suggestions of analgesia. Naloxone-induced reduction in tolerance to ischemia interacted significantly with the level of involvement expectancies. The suggestion of analgesia provided no significant naloxone-saline discrimination, but there was a significant interaction between variable memory task conditions and drug effects on the time ischemia was tolerated. These findings suggest that naloxone-opiate receptor interactions may depend on individual differences in attitudes to the situation, but may be potentiated by select environmental stimuli. Analyses of the effects of treatment on affective reactions to ischemia failed to show consistent results.

Adult↗

PubMed1995

Holding on to success: a case study in mental health care reform.

This article analyzes the changes experienced by a mental health care organization in response to environmental threats and fluctuating expectations. On a general, more theoretical level, the article demonstrates how processes of environmental selection as well as organizational adaptation shape organizational forms. On a concrete, applied level, those administrative practices are articulated that can help ensure that reform efforts are successful. Administrators also must be aware of the inertial forces operating upon stable organizational forms and work to ensure that the organization remains vital and open to change.

Community Mental Health Centers↗

PubMed2001

[Increasing incidence and mortality of non-Hodgkin lymphomas. An epidemiological review of recent studies on risk factors for non-Hodgkin lymphoma].

BACKGROUND: Non-Hodgkin's lymphoma (NHL) are among the small number of malignant tumors with markedly increasing incidence and mortality rates in the recent past. This trend is particularly obvious in industrialized countries. The causes of the observed increase remain unclear. METHODS: We conducted a Medline search to identify case control and cohort studies on medical, biological and selected environmental risk factors of non-Hodgkin's lymphoma published between 1992 and 1998. Methodological aspects and results of identified studies are presented in tabular form. We furthermore discuss the role of various risk factors for the observed trends in non-Hodgkin's lymphoma. RESULTS: We identified a total of 64 studies. Iatrogenic immunosuppression as well as numerous diseases associated with an impaired immune system have clearly been recognized as etiological factors for non-Hodgkin's lymphoma. However, they can explain only a small percentage of the rate increases of non-Hodgkin's lymphoma. Similarly, the HIV/AIDS epidemic in Germany is responsible only for a small proportion of the rising figures of non-Hodgkin's lymphoma; other viral agents are currently being associated with a few distinct subtypes of non-Hodgkin's lymphoma. Smoking and nutritional factors are weakly or not at all associated with non-Hodgkin's lymphoma and can not account for the disease trends. CONCLUSION: The observed secular rise in incidence and mortality of non-Hodgkin's lymphoma can only partly be explained. New epidemiologic studies should focus on risk factors associated with the function of the immune system and on possible interactions between different etiological factors.

Case-Control Studies↗

PubMed2002

Genetic control of monoterpene composition in the essential oil of Melaleuca alternifolia (Cheel).

Previous studies into the population structure of Melaleuca alternifolia by both isozyme and microsatellite analysis revealed little evidence for genetic structuring within genetic provenances. In contrast, analysis of the oil composition within these same regions showed distinct clustering of chemotypes within the provenances suggesting either that chemotype was not under genetic control, or that there is strong environmental selection for plant chemotypes. To investigate the level of genetic control of monoterpene composition in the essential oil of M. alternifolia, individuals representing the three extreme chemotypes of high terpinen-4-ol, high 1,8-cineole and high terpinolene were crossed with an individual with the commercially desirable high terpinen-4-ol oil profile. The progeny resulting from these crosses displayed oil profiles that were intermediate to that of the parent. Further analysis of the survey of oil chemotypes within the natural population also suggests that these intermediate chemotypes may arise naturally between regions containing high proportions of the extreme chemotypes. These results imply that there is a level of genetic structure for chemotype determination within the genetic provenance that is undetected by isozyme and microsatellite analysis. This information could play a vital role in the selection of appropriate genetic material to be used in future essential oil selection and breeding programs.

Journal Article↗

PubMed2005

A novel membrane bioreactor enhanced by effective microorganisms for the treatment of domestic wastewater.

The activated sludge membrane bioreactor (MBR) has been shown to have some advantages for the processing and reclamation of domestic wastewater. We hypothesized that certain microorganisms, chosen for their abilities to decompose the chemical components of raw sewage, would, when coupled with the MBR, significantly improve the stability and efficiency of this system. We selected environmental bacterial strains which oxidize ammonia and nitrites and produce protease, amylase, and cellulase for the development and testing of a novel biologically enhanced MBR (eMBR). We compared the eMBR with the activated sludge MBR. With the eMBR, the average values of effluent quality were: chemical oxygen demand (COD), 40 mg/l(average efficiency of removal 90.0%); and NH(4) (+)-N, 0.66 mg/l(average efficiency of removal 99.4%). Effluent qualities met the standard and were stable during the entire 90 days of this study. For the activated sludge MBR, the COD removal rate was 91.7%, and the NH(4) (+)-N removal (94.8%) was less than that of the eMBR. Start-up time for the eMBR was only 24-48 h, much shorter than the 7-8 days required to initiate function of the standard MBR. The biomass concentrations of total heterotrophic bacteria and autotrophic bacteria in the eMBR did not fluctuate significantly during the course of the study. Various kinds of microorganisms will establish an ecological balance in the reactor. Compared with the activated sludge MBR, the eMBR not only produced an excellent and stable quality of effluent but also resulted in a shorter time to start-up and significantly improved the efficiency of NH(4) (+)-N removal.

Bacteria↗

PubMed2006

Auditory response characteristics of the piebald odorous frog and their implications.

The piebald odorous frog (Odorrana schmackeri), the large odorous frog (Odorrana livida) and the concave-eared torrent frog (Amolops tormotus) are sympatric species living near the same torrent streams in the vicinity of Mt. Huangshan, China. A recent study demonstrated that A. tormotus can use sound signals involving ultrasonic components for communication in a noisy environment, and another sympatric species, O. livida, can also perceive ultrasonic sound. Here we report data on the hearing range of O. schmackeri by studying auditory evoked potentials and single-unit data from the torus semicircularis. This frog exhibits its two most sensitive peaks at 2 kHz and 3.5-4.0 kHz with thresholds <42 dB SPL, with an upper frequency limit of hearing at 8.5 kHz with threshold of 87 dB SPL. The upper limit is much lower than those of O. livida and A. tormotus, at 22 and 34 kHz, respectively. It suggests that sympatric species may respond differently to similar environmental selection pressures sculpting auditory communication systems.

Acoustic Stimulation↗

PubMed2006

Spatial encoding by bumblebees (Bombus impatiens) of a reward within an artificial flower array.

We presented bumblebees a spatial memory task similar to that used with other species (e.g., cats, dogs, and pigeons). In some conditions we allowed for presence of scent marks in addition to placing local and global spatial cues in conflict. Bumblebees (Bombus impatiens) were presented an array of artificial flowers within a flight cage, one flower offering reward (S+), while the others were empty (S-). Bees were tested with empty flowers. In Experiment 1, flowers were either moved at the time of testing or not. Bees returned to the flower in the same absolute position of the S+ (the flower-array-independent (FAI) position), even if it was in the wrong position relative to the S- and even when new flower covers prevented the use of possible scent marks. New flower covers (i.e., without possible scent marks) had the effect of lowering the frequency of probing behavior. In Experiment 2, the colony was moved between training and testing. Again, bees chose the flower in the FAI position of the S+, and not the flower that would be chosen using strictly memory for a flight vector. Together, these experiments show that to locate the S+ bees did not rely on scent marks nor the positions of the S-, though the S- were prominent objects close to the goal. Also, bees selected environmental features to remember the position of the S+ instead of relying upon a purely egocentric point of view. Similarities with honeybees and vertebrates are discussed, as well as possible encoding mechanisms.

Animals↗

PubMed2001

Evaluation of marine bacterial lysogens for development of a marine prophage induction assay.

The demonstrated relationship between carcinogenicity of a chemical compound in mammals and its tendency to cause prophage induction in bacteria provides a method for biologically based carcinogen screening. Because of the need for this type of screening and the abundance of lysogens in the marine environment, 14 isolates were evaluated for the degree of prophage induction in exponentially growing cultures in the presence of a known mutagen (0.5 microg/ml mitomycin C). Assays were performed both in liquid culture and in microtiter plates. Virus-like particles were enumerated by epifluorescence microscopy after staining with SYBR-Gold. Two isolates designated P94-4B3 (identified as Halomonas aquamarina) and P94-4S3 (identified as Pseudomonas aeruginosa) were further evaluated for potential use. Because of the rapid growth, larger size of its virus-like particles, and linear response to increasing dose of mitomycin C, the P. aeruginosa st. P94-4S3 was determined a better candidate for the marine prophage induction assay (MPIA). The Pseudomonas isolate was then used in several experiments for the development and optimization of the MPIA procedure. Initial screenings of the MPIA were also performed with selected environmental pollutants.

Journal Article↗

PubMed1995

The composition and function of reptilian pulmonary surfactant.

In mammals, the surface tension of the fluid lining the inner lung greatly contributes to the work of breathing. Surface tension is modified by the secretion of a mixture of surface active lipids and proteins (termed pulmonary surfactant). A disaturated phospholipid (DSP), predominantly dipalmitoylphosphatidylcholine (DPPC), can eliminate surface tension under high dynamic compression. Cholesterol (CHOL) and unsaturated phospholipids (USP) promote respreading upon inflation by converting DPPC to the disordered liquid-crystalline state. It appeared to us that a surfactant rich in DPPC, which has a high phase transition temperature of 41 degrees C, is likely to be of only limited use in the lungs of reptiles, many of which have preferred body temperatures between 20 and 30 degrees C. We review here the presence and composition of surfactant in species from the three subclasses of the Reptilia and relate these to lung structure and function, phylogeny and environmental selection pressures such as body temperature. We also discuss the function of reptilian surfactant and the factors which control surfactant turnover. Large amounts of pulmonary surfactant have been found in all reptiles so far examined. In general, warmer reptiles have greater amounts of surfactant which is also relatively enriched in DSP. Cold lizards (18 degrees C) have significantly elevated levels of surfactant cholesterol. As in all vertebrates, PC is always the dominant phospholipid (60-80%). Unlike mammals, phosphatidylglycerol (PG) is absent, with the exception of one species. The remaining phospholipid groups are present to varying degrees. The saturated fatty acid, palmitic acid (16:0) is the dominant acyl group, oleic acid (18:1) is the dominant mono-unsaturated fatty acid, and polyunsaturates comprise only about 20% of the total fatty acid profile. For two species of dragon lizards, short term changes in temperature do not affect the fatty acids, but protracted periods of cold significantly decrease the presence of 16:0 in turtle lavage (Lau and Keough, Can.J. Biochem. 59: 208-219, 1981). Surfactant appears to function as an antiglue in most reptiles, serving to lower opening pressure, and decrease the work of breathing. However, surface tension forces generally do not influence reptilian lung compliance, suggesting that the primary functions of mammalian surfactant are not necessarily relevant to reptiles.

Animals↗

PubMed1993

Diarrhoeal disease: current concepts and future challenges. Epidemiology of diarrhoeal diseases in developed countries.

Diarrhoeal diseases are a common problem in industrialized countries, resulting in appreciable morbidity and mortality. While the total burden of these illnesses is much less than that in developing countries, the same basic disease risk factors influence transmission. This article reviews selected environmental, host and pathogen-specific factors which shape the epidemiology of infectious diarrhoea in developed countries. The effective adaptation of techniques from molecular biology, such as plasmid analysis, deoxyribonucleic acid hybridization, and the polymerase chain reaction, to studies of diarrhoeal disease epidemiology is also discussed.

Aged↗

PubMed2026

From colonization to infection: Genomic evolution of Clostridioides difficile pathogenesis.

Clostridioides difficile is a spore-forming, toxin-producing anaerobe that is a leading cause of healthcare-associated infections. Its success as a pathogen reflects a complex interplay between bacterial evolution, virulence regulation, ecological adaptation, environmental selection, and host susceptibility. Comparative genomics has revealed deep C. difficile lineage diversification, driven by mobile genetic elements and selective pressures from antibiotics and host environments. These events affect strain-specific virulence by shaping the organization and regulation of the pathogenicity toxin loci, metabolic adaptations for nutrient utilization, and enhanced spore resilience. This review integrates evolutionary and genomic perspectives to illustrate how adaptive diversification has sculpted C. difficile pathogenesis and epidemic success.

CP: microbiology↗

PubMed2005

Recent advances on the taxonomy, systematics and epidemiology of Trichinella.

Since Owen first described Trichinella as a human pathogen in 1835, the number of organisms comprising this genus has grown dramatically. Where it was once thought to be a monospecific group, this genus is now comprised of eight species and three additional genotypic variants that have yet to be taxonomically defined. Along with the growth in the genus and description of the parasites has come a concomitant increase in our understanding of the epidemiology and geographical distribution of these organisms. Recent expansion of the non-encapsulated group to include three species biologically defined by their unique host ranges encompassing mammals, birds and reptiles, has raised substantial questions as to the term, 'Trichinella-free' as it applies to geographical localities. A true appreciation of the adaptability of this genus to host and environmental selection factors, as well as its dissemination to the far reaches of the world can best be appreciated by reviewing what we know and what we hope to know about this ancient and elusive parasite. The review herein consolidates our current understanding of the taxonomy, epidemiology, and phylogeny of the genus Trichinella, and identifies areas where data are lacking and our knowledge requires additional clarification.

Animals↗

PubMedDate not supplied

Diversity in a promiscuous group of rhizobia from three Sesbania spp. colonizing ecologically distinct habitats of the semi-arid Delhi region.

Sesbania-rhizobia associations have immense significance in soil amelioration programs for diverse habitats. Diversity in symbiotic properties, LPS profiles, Sym plasmid and rhizobiophage sensitivity of 28 root- and stem-nodulating bacterial isolates of three Sesbania species (S. sesban, S. aegyptica and S. rostrata) inhabiting six ecologically distinct sites of semi-arid Delhi region was analyzed. The isolates were highly promiscuous among the symbiotic partners (Sesbania spp.). The root nodules formed by all the isolates were morphologically similar but they differed in their symbiotic efficiency and effectiveness. 16S rDNA sequence analyses revealed that root nodule isolates of sesbanias belong to diverse rhizobial taxa (Sinorhizobium saheli, S. meliloti, Rhizobium huautlense) whereas stem-nodule isolates were strictly Azorhizobium caulinodans. Sinorhizobium spp. seem to dominate as microsymbiont partner of Sesbania in the Delhi region. The genetic diversity revealed by cluster analyses based on NPC-PCR reflects sorting of isolates across the ecological gradient. Parallel diversity was also observed in the grouping based on LPS profiles and sym plasmid (NPC-PCR). Segregation of different rhizobial taxa into distinct types/clusters based on LPS and NPC-PCR analyses suggest its significance in the circumscription of the taxa. However, subtypes and subclusters showed their sorting across the ecological gradients. Sesbania rhizobia showed extremely high specificity to rhizobiophages. Enormous diversity in LPS profiles and high specificity of rhizobiophages might be the result of environmental selection pressures operating in ecologically distinct habitats. The ability of sesbanias to enter into effective symbioses with different rhizobial taxa and colonize diverse habitats with various biotic and abiotic stresses appears to contribute to its wide ecological amplitude.

Alphaproteobacteria↗