A novel trehalose synthesizing pathway in the hyperthermophilic Crenarchaeon <Emphasis Type="Italic">Thermoproteus tenax</Emphasis>: the unidirectional TreT pathway

In the genome of the hyperthermophilic archaeon Thermoproteus tenax a gene (treS/P) encoding a protein with similarity to annotated trehalose phosphorylase (TreP), trehalose synthase (TreS) and more recently characterized trehalose glycosyltransferring synthase (TreT) was identified. The treS/P gene as well as an upstream located ORF of unknown function (orfY) were cloned, heterologously expressed in E. coli and purified. The enzymatic characterization of the putative TreS/P revealed TreT activity. However, contrary to the previously characterized reversible TreT from Thermococcus litoralis and Pyrococcus horikoshii, the T. tenax enzyme is unidirectional and catalyzes only the formation of trehalose from UDP (ADP)-glucose and glucose. The T. tenax enzyme differs from the reversible TreT of T. litoralis by its preference for UDP-glucose as co-substrate. Phylogenetic and comparative gene context analyses reveal a conserved organization of the unidirectional TreT and OrfY gene cluster that is present in many Archaea and a few Bacteria. In contrast, the reversible TreT pathway seems to be restricted to only a few archaeal (e.g. Thermococcales) and bacterial (Thermotogales) members. Here we present a new pathway exclusively involved in trehalose synthesis--the unidirectional TreT pathway--and discuss its physiological role as well as its phylogenetic distribution.     

Relative efficiency of preferred and nonpreferred patterns of lateralized foraging in the gentle lemur (Hapalemur griseus)

Lateralized patterns of hand use in species-typical bamboo shoot foraging were evaluated for efficiency in five female and six male gentle lemurs (Hapalemur griseus sp.). Efficiency was defined as amount of time required to complete a foraging response sequence. The foraging pattern consisted of four component movements: PULL-IN, COUNTERFORCE, TURN, and FEED-IN. These component movements had been shown in a previous study to incorporate lateral hand biases that formed subsets of patterns that were characteristic for each gentle lemur. The duration of each foraging sequence was measured from the beginning of the first component to the initiation of the terminal component. Frequency of use scores were employed to divide the pattern sequences of each subject into preferred and nonpreferred categories. A within-subjects comparison of the mean durations of preferred patterns (M = 2.56 sec) with those of non- preferred patterns (M = 3.02 sec) found that preferred patterns were executed more rapidly, t(10) = 3.36, P = .007. A multiple regression showed that order of pattern preference accounted for 89% of the variance in mean duration of response time (R² = .89, P = .056). Thus, the use of preferred lateralized hand patterns resulted in more rapid bamboo shoot harvesting. Speed in foraging may be regarded as an adaptive strategy for a species that subsists on a high bulk, low nutrient density food such as bamboo. © 1995 Wiley-Liss, Inc.     

Molecular quantification of symbiotic dinoflagellate algae of the genus Symbiodinium

The dinoflagellate microalga Symbiodinium is the dominant algal symbiont in corals and related marine animals. To explore the incidence of mixed infections, methods employing real-time quantitative polymerase chain reaction (QPCR) and fluorescence in situ hybridization (FISH) were developed. In experiments focusing on Symbiodinium clades A and B, QPCR and FISH results were well correlated and generally more precise and sensitive than those from the endpoint PCR-restriction fragment length polymorphism analysis (PCR-RFLP) traditionally used for this application, thus increasing the detected incidence of mixed infections. For example, the prevalence of mixed infections in the sea anemone Condylactis gigantea was 40% by PCR-RFLP and 80%-90% by QPCR and FISH. However, the use of QPCR and FISH was limited by inter-host variation in the rRNA gene copy number per Symbiodinium cell, precluding any single conversion factor between QPCR signal and Symbiodinium cell number; and one FISH probe that gave excellent hybridization efficiency with cultured Symbiodinium yielded variable results with Symbiodinium from symbioses. After controlling for these caveats, QPCR studies revealed that field-collected hosts previously described as universally unialgal bore up to 1.6% of the alternative clade. Further research is required to establish the contribution that algal cells at low density in symbiosis and external to the symbiosis make to the minor clade.     

Cultivo biotecnológico de macrohongos comestibles: una alternativa en la obtención de nutracéuticos

Macromycetes have been part of the human culture for thousand years, and have been reported as food in the most important civilizations in history. Many nutraceutical properties of macromycetes have been described, such as anti-cancer, anti-tumour, cholesterol lowering, antiviral, antibacterial, or immunomodulatory, among others. Given that production of mushrooms by traditional cultivation and extraction of bioactive metabolites is very difficult in some cases, biotechnology is essential for the development of profitable and productive techniques for obtaining these metabolites. It is the development of this technology, and the ease in which it enables the use of its variables that has allowed mycelium to be cultivated in liquid medium of macrofungi, with a significant reduction in time and an increased production of metabolites. This increased production has led to the study of compounds that have medicinal, nutriceutical and quasi-farmaceutical potential, in the exhausted media and the mycelium. The aim of this review is to provide an overview of the use of liquid-state fermentation as a technological tool for obtaining edible fungi, and the study of these and their metabolites, by describing the different cultivation conditions used in recent years, as well as the results obtained. The relevance of Agaricus, Flammulina, Grifola, Pleurotus and Lentinula genera, will also be discussed, with emphasis on the last one, since Shiitake has been always considered as the ultimate medicinal mushroom.     

Quantitative trait loci involved in the reproductive success of a parasitoid wasp

Dissecting the genetic basis of intraspecific variations in life history traits is essential to understand their evolution, notably for potential biocontrol agents. Such variations are observed in the endoparasitoid Cotesia typhae (Hymenoptera: Braconidae), specialized on the pest Sesamia nonagrioides (Lepidoptera: Noctuidae). Previously, we identified two strains of C. typhae that differed significantly for life history traits on an allopatric host population. To investigate the genetic basis underlying these phenotypic differences, we used a quantitative trait locus (QTL) approach based on restriction site‐associated DNA markers. The characteristic of C. typhae reproduction allowed us generating sisters sharing almost the same genetic content, named clonal sibship. Crosses between individuals from the two strains were performed to generate F2 and F8 recombinant CSS. The genotypes of 181 clonal sibships were determined as well as the phenotypes of the corresponding 4,000 females. Informative markers were then used to build a high‐quality genetic map. These 465 markers spanned a total length of 1,300 cM and were organized in 10 linkage groups which corresponded to the number of C. typhae chromosomes. Three QTLs were detected for parasitism success and two for offspring number, while none were identified for sex ratio. The QTLs explained, respectively, 27.7% and 24.5% of the phenotypic variation observed. The gene content of the genomic intervals was investigated based on the genome of C. congregata and revealed 67 interesting candidates, as potentially involved in the studied traits, including components of the venom and of the symbiotic virus (bracovirus) shown to be necessary for parasitism success in related wasps.