Rhodobacteraceae on the marine brown alga Fucus spiralis are abundant and show physiological adaptation to an epiphytic lifestyle

Macroalgae harbour specific microbial communities on their surface that have functions related to host health and defence. In this study, the bacterial biofilm of the marine brown alga Fucus spiralis was investigated using 16S rRNA gene amplicon-based analysis and isolation of bacteria. Rhodobacteraceae (Alphaproteobacteria) were the predominant family constituting 23% of the epibacterial community. At the genus level, Sulfitobacter, Loktanella, Octadecabacter and a previously undescribed cluster were most abundant, and together they comprised 89% of the Rhodobacteraceae. Supported by a specific PCR approach, 23 different Rhodobacteraceae-affiliated strains were isolated from the surface of F. spiralis, which belonged to 12 established and three new genera. For seven strains, closely related sequences were detected in the 16S rRNA gene dataset. Growth experiments with substrates known to be produced by Fucus spp. showed that all of them were consumed by at least three strains, and vitamin B₁₂ was produced by 70% of the isolates. Since growth of F. spiralis depends on B₁₂ supplementation, bacteria may provide the alga with this vitamin. Most strains produced siderophores, which can enhance algal growth under iron-deficient conditions. Inhibiting properties against other bacteria were only observed when F. spiralis material was present in the medium. Thus, the physiological properties of the isolates indicated adaption to an epiphytic lifestyle.     

Lipolysis drives expression of the constitutively active receptor GPR3 to induce adipose thermogenesis

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The Prevalence of <Emphasis Type="Italic">Trypanosoma cruzi</Emphasis>, the Causal Agent of Chagas Disease,in Texas Rodent Populations

Rodent species were assessed as potential hosts of Trypanosoma cruzi, the etiologic agent of Chagas disease, from five sites throughout Texas in sylvan and disturbed habitats. A total of 592 rodents were captured, resulting in a wide taxonomic representation of 11 genera and 15 species. Heart samples of 543 individuals were successfully analyzed by SybrGreen-based quantitative PCR (qPCR) targeting a 166 bp fragment of satellite DNA of T. cruzi. Eight rodents representing six species from six genera and two families were infected with T. cruzi. This is the first report of T. cruzi in the pygmy mouse (Baiomys taylori) and the white-footed mouse (Peromyscus leucopus) for the USA. All infected rodents were from the southernmost site (Las Palomas Wildlife Management Area). No differences in pathogen prevalence existed between disturbed habitats (5 of 131 tested; 3.8%) and sylvan habitats (3 of 40 tested; 7.5%). Most positives (n = 6, 16% prevalence) were detected in late winter with single positives in both spring (3% prevalence) and fall (1% prevalence). Additionally, 30 Triatoma insects were collected opportunistically from sites in central Texas. Fifty percent of these insects, i.e., 13 T. gerstaeckeri (68%), and two T. lecticularia (100%) were positive for T. cruzi. Comparative sequence analyses of 18S rRNA of samples provided identical results with respect to detection of the presence or absence of T. cruzi and assigned T. cruzi from rodents collected in late winter to lineage TcI. T. cruzi from Triatoma sp. and rodents from subsequent collections in spring and fall were different, however, and could not be assigned to other lineages with certainty.     

Rule-based spatial modeling with diffusing,geometrically constrained molecules

Background  

We suggest a new type of modeling approach for the coarse grained, particle-based spatial simulation of combinatorially complex chemical reaction systems. In our approach molecules possess a location in the reactor as well as an orientation and geometry, while the reactions are carried out according to a list of implicitly specified reaction rules. Because the reaction rules can contain patterns for molecules, a combinatorially complex or even infinitely sized reaction network can be defined.     

Odor Hedonics: Connection With Emotional Response Estimated by Autonomic Parameters

The aim of this paper is to analyse the relationship betweenself-report hedonic evaluations and the physiological expressionof emotion in response to odorants. We try to solve the followingquestions: (1) Is it possible to find any experimental evidencethat the sense of smell is linked with emotion? (2) What kindof odorants can be distinguished by autonomic analysis? (3)Is there a link between hedonics and autonomic information?The effects of odorants on the emotional process were estimated,in terms of autonomic nervous system (ANS) activity. Fifteensubjects inhaled five odorants as olfactory stimuli: lavender(LAV), ethyl acetoacetate (EAA), camphor (CAM), acetic acid(AA) and butyric acid (BA). After inhaling the odorant, subjectswere requested to fill out an 11-point hedonic scale to rateits pleasantness versus unpleasantness. ANS parameters wereas follows: two electrodermal responses, skin potential (SP)and resistance (SR); two thermovascular parameters, skin bloodflow (SBF) and skin temperature (ST); and two cardiorespiratoryparameters: instantaneous respiratory frequency (IRF) and instantaneousheart rate (IHR). Simultaneous recording of six parameters showedthat specific autonomic patterns were associated with each odorant.An analysis of variance made it possible to differentiate amongthe five odorants. Two-by-two odorant comparisons for autonomicresponses using Tukey's HSD multiple comparison test only permitteddifferentiation between pleasant odorants (LAV and EAA) andunpleasant (AA and BA) ones, but camphor was differentiatedfrom both pleasant and unpleasant odorants. Each odorant elicitedresponses in the different parameters, yet subjects respondedthrough their preferential channels; an average of two channelswas used by each subject. These results when compared with thoseobtained with other senses (visual and auditory). did not evidencethe postulated preferential link between olfaction and emotion.A'strong link between hedonics and ANS response could be demonstratedwhen considering each subject and mainly through his/her preferentialchannel(s); conversely a weak correlation (SR duration excepted)was obtained between inter-subjects' hedonic evaluation. Itseems that for a given population the autonomic response reflectthe odor valence only through some parameters related to themain preferential channel(s) and thus the global autonomic patternhas to be considered. Chem. Senses 22: 237–248, 1997.