Transformations of chloroguaiacols, chloroveratroles, and chlorocatechols by stable consortia of anaerobic bacteria

Metabolically stable consortia of anaerobic bacteria obtained by enrichment of sediment samples with 3,4,5-trimethoxybenzoate (TMBA), 3,4,5-trihydroxybenzoate (gallate [GA]), or 5-chlorovanillin (CV) were used to study the anaerobic transformation of a series of chloroveratroles, chloroguaiacols, and chlorocatechols used as cosubstrates. Experiments were carried out with growing cultures, and the following pathways were demonstrated for metabolism of the growth substrates: (i) TMBA produced GA, which was further degraded without the formation of aromatic intermediates; (ii) GA formed pyrogallol, which was stable to further transformation; and (iii) CV was degraded by a series of steps involving de-O-methylation, oxidation of the aldehyde group, and decarboxylation to 3-chlorocatechol before ring cleavage. Mono-de-O-methylation of the cosubstrates occurred rapidly in the order 4,5,6-trichloroguaiacol greater than 3,4,5-trichloroguaiacol approximately 3,4,5-trichloroveratrole approximately tetrachloroveratrole greater than tetrachloroguaiacol and was concomitant with degradation of the growth substrates. For the polymethoxy compounds--chloroveratroles, 1,2,3-trichloro-4,5,6-trimethoxybenzene, and 4,5,6-trichlorosyringol--de-O-methylation took place sequentially. The resulting chlorocatechols were stable to further transformation until the cultures had exhausted the growth substrates; selective dechlorination then occurred with the formation of 3,5-dichlorocatechol from 3,4,5-trichlorocatechol and of 3,4,6-trichlorocatechol from tetrachlorocatechol. 2,4,5-, 2,4,6-, and 3,4,5-trichoroanisole and 2,3,4,5-tetrachloroanisole were de-O-methylated, but the resulting chlorophenols were resistant to dechlorination. These results extend those of a previous study with spiked sediment samples and their endogenous microflora and illustrate some of the transformations of chloroguaiacols and chlorocatechols which may be expected to occur in anaerobic sediments.     

Multiple Feedbacks Contribute to a Centennial Legacy of Reindeer on Tundra Vegetation

Historical contingency is the impact of past events, like the timing and order of species arrival, on community assembly, and can sometimes result in alternative stable states of ecological communities. Large herbivores, wild and domestic, can cause profound changes in the structure and functioning of plant communities and therefore probably influence historical contingency; however, little empirical data on the stability of such shifts or subsequent drivers of stability are available. We studied the centennial legacy of reindeer (Rangifer tarandus) pressure on arctic tundra vegetation by considering historical milking grounds (HMGs): graminoid- and forb-dominated patches amid shrub-dominated tundra, formed by historical Sami reindeer herding practices that ended approximately 100 years ago. Our results show that the core areas of all studied HMGs remained strikingly stable, being hardly invaded by surrounding shrubs. Soil nitrogen concentrations were comparable to heavily grazed areas. However, the HMGs are slowly being reinvaded by vegetative growth of shrubs at the edges, and the rate of ingrowth increased with higher mineral N availability. Furthermore, our data indicate that several biotic feedbacks contribute to the stability of the HMGs: increased nutrient turnover supporting herbaceous vegetation, strong interspecific competition preventing invasion and herbivore damage to invading shrubs. In particular, voles and lemmings appear to be important, selectively damaging shrubs in the HMGs. We concluded that HMGs provide clear evidence for historical contingency of herbivore effects in arctic ecosystems. We showed that several biotic feedbacks can contribute to subsequent vegetation stability, but their relative importance will vary in time and space.     

What Is the Future for Zoos and Aquariums?

ABSTRACT

Animal welfare concerns have plagued the professional zoo and aquarium field for decades. Societal differences remain concerning the well-being of animals, but it appears a shift is emerging. Scientific studies of animal welfare have dramatically increased, establishing that many previous concerns were not misguided public empathy or anthropomorphism. As a result, both zoo and aquarium animal welfare policy and science are now at the center of attention within the world’s professional zoos and aquariums. It is now possible to view a future that embraces the well-being of individual captive exotic animals, as well as that of their species, and one in which professional zoos and aquariums are dedicated equally to advancing both. Though the ethics of keeping exotic animals and animals from the wild in captivity are still a contentious subject both outside and even within the profession, this study argues. We argue that this path forward will substantially improve most zoo and aquarium animals' welfare and could significantly reduce societal concerns. If animal welfare science and policy are strongly rooted in compassion and embedded in robust accreditation systems, the basic zoo/aquarium paradigm will move toward a more thoughtful approach to the interface between visitors and animals. It starts with a fundamental commitment to the welfare of individual animals.     

Intracellular Distribution of 5' Nucleotidase in Rat Liver

The intracellular distribution of 5' nucleotidase was investigated in rat liver by biochemical analysis of cell fractions obtained by differential centrifugation. The enzymatic activity was measured by determination of the inorganic phosphorus liberated from 5' nucleotides. The 5' nucleotidase activity was mainly found in the nuclear and microsomal fractions. An attempt to extract the enzyme from these fractions with Mg⁺⁺ ion solutions was unsuccessful. It is concluded that 5' nucleotidase is actually present in the nuclear and microsomal fractions of rat liver cells.     

cGMP and cAMP cause pulmonary vasoconstriction in the presence of hemolysate.

We recently reported that addition of a small amount of hemolysate to the salt solution that perfused isolated rat lungs hypersensitized the vasculature to subsequent additions of ANG II or exposure to hypoxia, and addition of NO gas (. NO) to the perfusate that contained hemolysate caused a strong vasoconstrictor rather than a vasodilator response. In the present study, we demonstrate that CO and the secondary messengers cGMP and cAMP (usually associated with vasodilation) exert similar effects in hemolysate-perfused lungs. Analogs of the cyclic nucleotides cGMP or cAMP (8-bromo-cGMP and dibutyryl-cAMP, respectively) caused profound vasoconstriction in the isolated rat lung perfused with a salt solution that contained hemolysate. The cGMP- or cAMP-analog-induced vasoconstriction was inhibited by chemically dissimilar Ca2+ antagonists, by the protein phosphatase inhibitor okadaic acid, and, to a lesser degree, by protein kinase inhibitor H-7. Antiphosphothreonine immunoblotting demonstrated that lungs perfused with hemolysate exhibit increased phosphorylation of several proteins. These data indicate that, in the presence of hemolysate, pulmonary vasculature responds to nominally vasodilatory stimuli, including analogs of cGMP and cAMP, with vasoconstriction rather than vasodilation. The importance of our finding is the paradoxical nature of the response to (analogs of) cyclic nucleotides because, to our knowledge, cyclic nucleotide-induced vasoconstriction has not been previously reported.     

Discovery of selective and orally available spiro-3-piperidyl ATP-competitive MK2 inhibitors

The identification of a potent, selective, and orally available MK2 inhibitor series is described. The initial absence of oral bioavailability was successfully tackled by moving the basic nitrogen of the spiro-4-piperidyl moiety towards the electron-deficient pyrrolepyridinedione core, thereby reducing the pK_a and improving Caco-2 permeability. The resulting racemic spiro-3-piperidyl analogues were separated by chiral preparative HPLC, and the activity towards MK2 inhibition was shown to reside mostly in the first eluting stereoisomer. This led to the identification of new MK2 inhibitors, such as (S)-23, with low nanomolar biochemical inhibition (EC₅₀ 7.4 nM) and submicromolar cellular target engagement activity (EC₅₀ 0.5 μM).     

Knowledge and beliefs of international travellers about the transmission and prevention of HIV infection.

OBJECTIVES: To measure the perceived risk of acquired immunodeficiency syndrome (AIDS) among international travellers, to measure their knowledge of the transmission and prevention of HIV infection abroad and to identify some of the determinants of this knowledge. DESIGN: Survey. SETTING: Travellers'' immunization clinic providing mostly primary preventive care to international travellers. PARTICIPANTS: All clients aged 18 to 50 years seen at the clinic between Oct. 2 and Dec. 21, 1989, before their departure. MAIN OUTCOME MEASURES: Sixteen statements measured knowledge of transmission and prevention of HIV infection. Standardized scales measured health beliefs. RESULTS: The response rate was 81% (331/409). Compared with other diseases AIDS was perceived to be associated with a low risk except by those travelling to countries with a high prevalence of AIDS. Most of the clients were found to have a good knowledge of HIV transmission to travellers, although some myths remained popular and some real routes of transmission, especially blood, remained underrated. In all, 70% of the subjects believed in the efficacy of condoms when used with local people, as compared with 79% when used with other tourists; this difference was greatest among travellers who perceived AIDS as being particularly severe but difficult to prevent. The determinants of the knowledge of HIV transmission and prevention were a high level of education, a mother tongue other than French, unmarried status, a high prevalence of AIDS at the destination, the duration of the trip and a high perceived risk of HIV infection. CONCLUSIONS: Counselling should teach travellers (a) not to underestimate their risk of HIV infection during their trip, (b) to decrease the risk of requiring health care in developing countries and (c) to rely on their own prudent sexual behaviour rather than on their assessment of the level of risk posed by the environment.