Molecular phylogeny of the fungus gnat tribe Exechiini (Mycetophilidae, Diptera)

The phylogenetic relationships within the fungus gnat tribe Exechiini have been left unattended for many years. Recent studies have not shed much light on the intergeneric relationship within the tribe. Here the first attempt to resolve the phylogeny of the tribe Exechiini using molecular markers is presented. The nuclear 18S and the mitochondrial 16S, and cytochrome oxidase subunit I (COI) genes were successfully sequenced for 20 species representing 15 Exechiini genera and five outgroup genera. Bayesian, maximum parsimony and maximum likelihood analyses revealed basically congruent tree topologies and the monophyly of Exechiini, including the genus Cordyla , is confirmed. The molecular data corroborate previous morphological studies in several aspects. Cordyla is found in a basal clade together with Brachypeza , Pseudorymosia and Stigmatomeria . The splitting of the genera Allodiopsis s.l. and Brevicornu s.l. as well as the sistergroup relationship of Exechia and Exechiopsis is also supported. The limited phylogenetic information provided by morphological characters is mirrored in the limited resolution of the molecular markers used in this study. Short internal and long-terminal branches obtained may indicate a rapid radiation of the Exechiini genera during a short evolutionary period.     

Moesin contributes an essential structural role in Drosophila photoreceptor morphogenesis

Ezrin-Radixin-Moesin (ERM) family proteins organize heterogeneous sub-plasma membrane protein scaffolds that shape membranes and their physiology. In Drosophila oocytes and imaginal discs, epithelial organization, fundamental to development and physiology, is devastated by the loss of Moesin. Here, we show that Moesin is crucial for Drosophila photoreceptor morphogenesis. Beyond its requirement for retinal epithelium integrity, Moesin is essential for the proper assembly of the apical membrane skeleton that builds the photosensitive membrane, the rhabdomere. Moesin localizes to the rhabdomere base, a dynamic locus of cytoskeletal reorganization and membrane traffic. Downregulation of Moesin through RNAi or genetic loss of function profoundly disrupts the membrane cytoskeleton and apical membrane organization. We find normal levels and distribution of Moesin in photoreceptors of a Moesin mutant previously regarded as protein null, suggesting alternative interpretations for studies using this allele. Our results show an essential structural role for Moesin in photoreceptor morphology.     

Expression of a synthetic E. coli heat-labile enterotoxin B sub-unit (LT-B) in maize

We have produced the B subunit of the enterotoxigenic Escherichia coli (ETEC) heat-labile enterotoxin (LT-B) in transgenic maize seed. LT-B is a model antigen that induces a strong immune response upon oral administration and enhances immune responses to conjugated and co-administered antigens. Using a synthetic LT-B gene with optimized codon sequence, we examined the role of promoters and the SEKDEL endoplasmic reticulum retention motif in LT-B accumulation in callus and in kernels. Two promoters, the constitutive CaMV 35S promoter and the maize 27 kDa gamma zein promoter, which directs endosperm-specific gene expression in maize kernels, regulated LT-B expression. Ganglioside-dependent ELISA analysis showed that using the constitutive promoter, maximum LT-B level detected in callus was 0.04% LT-B in total aqueous-extractable protein (TAEP) and 0.01% in R₁ kernels of transgenic plants. Using the gamma zein promoter, LT-B accumulation reached 0.07% in R₁ kernels. The SEKDEL resulted in increased LT-B levels when combined with the gamma zein promoter. We monitored LT-B levels under greenhouse and field conditions over three generations. Significant variability in gene expression was observed between transgenic events, and between plants within the same event. A maximum of 0.3% LT-B in TAEP was measured in R₃ seed of a transgenic line carrying CaMV 35S promoter/LT-B construct. In R₃ seed of a transgenic line carrying the gamma zein promoter/LT-B construct, up to 3.7% LT-B in TAEP could be detected. We concluded that maize seed can be used as a production system for functional antigens.     

Bonobo (Pan paniscus) Spatial Memory and Communication in a 20-hectare Forest

We used an artificial language as a tool for the study of spatial memory organization in a young Pan paniscus. In the first experiment, we showed the bonobo a road sign just outside its indoor sleeping area. The sign indicated, by means of arbitrarily designated geometrical shapes (lexigrams), where food was hidden. Only 2 of the 15 locations were visible from the sign. Distances ranged up to 170 m from the sign. In 99 of 127 test trials the bonobo went directly to the designated location on its first move. In a second experiment, we presented the road sign at varied points in the woods rather than at the original fixed place. In these trials the goal was a preferred toy. The bonobo's human companions were never told the location of the goal and distances were up to 650 m. In all 12 trials the bonobo led its companions to the designated place via an efficient path. The bonobo appeared to be able to move, based on the information provided by a lexigram, from almost any arbitrary starting location in its 20-ha environment to any one of the numerous goal locations.     

Measurement and analysis of gas exchange during exercise using a programmable calculator

Although exercise testing is useful in the diagnosis and management of cardiovascular and pulmonary diseases, a rapid comprehensive method for measurement of ventilation and gas exchange has been limited to expensive complex computer-based systems. We devised a relatively inexpensive, technically simple, and clinically oriented exercise system built around a desktop calculator. This system automatically collects and analyzes data on a breath-by-breath basis. Our calculator system overcomes the potential inaccuracies of gas exchange measurement due to water vapor dilution and mismatching of expired flow and gas concentrations. We found no difference between the calculator-derived minute ventilation, CO2 production, O2 consumption, and respiratory exchange ratio and the values determined from simultaneous mixed expired gas collections in 30 constant-work-rate exercise studies. Both tabular and graphic displays of minute ventilation, CO2 production, O2 consumption, respiratory exchange ratio, heart rate, end-tidal O2 tension, end-tidal CO2 tension, and arterial blood gas value are included for aid in the interpretation of clinical exercise tests.     

Ultrahigh resolution structures of nitrophorin 4: heme distortion in ferrous CO and NO complexes

Nitrophorin 4 (NP4), a nitric oxide (NO)-transport protein from the blood-sucking insect Rhodnius prolixus, uses a ferric (Fe3+) heme to deliver NO to its victims. NO binding to NP4 induces a large conformational change and complete desolvation of the distal pocket. The heme is markedly nonplanar, displaying a ruffling distortion postulated to contribute to stabilization of the ferric iron. Here, we report the ferrous (Fe2+) complexes of NP4 with NO, CO, and H2O formed after chemical reduction of the protein and the characterization of these complexes by absorption spectroscopy, flash photolysis, and ultrahigh-resolution crystallography (resolutions vary from 0.9 to 1.08 A). The absorption spectra, both in solution and in the crystal, are typical for six-coordinated ferrous complexes. Closure and desolvation of the distal pocket occurs upon binding CO or NO to the iron regardless of the heme oxidation state, confirming that the conformational change is driven by distal ligand polarity. The degree of heme ruffling is coupled to the nature of the ligand and the iron oxidation state in the following order: (Fe3+)-NO > (Fe2+)-NO > (Fe2+)-CO > (Fe3+)-H2O > (Fe2+)-H2O. The ferrous coordination geometry is as expected, except for the proximal histidine bond, which is shorter than typically found in model compounds. These data are consistent with heme ruffling and coordination geometry serving to stabilize the ferric state of the nitrophorins, a requirement for their physiological function. Possible roles for heme distortion and NO bending in heme protein function are discussed.     

Disturbance frequency and community structure in a twenty-five year intervention study

Models of community regulation commonly incorporate gradients of disturbance inversely related to the role of biotic interactions in regulating intermediate trophic levels. Higher trophic-level organisms are predicted to be more strongly limited by intermediate levels of disturbance than are the organisms they consume. We used a manipulation of the frequency of hydrological disturbance in an intervention analysis to examine its effects on small-fish communities in the Everglades, USA. From 1978 to 2002, we monitored fishes at one long-hydroperiod (average 350 days) and at one short-hydroperiod (average 259 days; monitoring started here in 1985) site. At a third site, managers intervened in 1985 to diminish the frequency and duration of marsh drying. By the late 1990s, the successional dynamics of density and relative abundance at the intervention site converged on those of the long-hydroperiod site. Community change was manifested over 3 to 5 years following a dry-down if a site remained inundated; the number of days since the most recent drying event and length of the preceding dry period were useful for predicting population dynamics. Community dissimilarity was positively correlated with the time since last dry. Community dynamics resulted from change in the relative abundance of three groups of species linked by life-history responses to drought. Drought frequency and intensity covaried in response to hydrological manipulation at the landscape scale; community-level successional dynamics converged on a relatively small range of species compositions when drought return-time extended beyond 4 years. The density of small fishes increased with diminution of drought frequency, consistent with disturbance-limited community structure; less-frequent drying than experienced in this study (i.e., longer return times) yields predator-dominated regulation of small-fish communities in some parts of the Everglades. Electronic Supplementary Material Supplementary material is available for this article at     

Estrogen suppresses IL-1beta-mediated induction of COX-2 pathway in rat cerebral blood vessels

Interleukin (IL)-1beta is a potent inducer of inflammatory prostaglandins, which are important mediators of vascular response to cerebral injury, whereas estrogen reduces brain injury in models of ischemic stroke. Thus we examined the effects of in vivo IL-1beta exposure on cerebrovascular cyclooxygenase (COX)-2 expression and function in an animal model of chronic estrogen replacement. Estrogen-treated and nontreated ovariectomized female rats received IL-1beta injections (10 microg/kg i.p.), and then cerebral vessels were isolated for biochemical and contractile measurements. In estrogen-deficient rats, IL-1beta induced cerebrovascular COX-2 protein expression; a peak response occurred 3 h after injection. COX-2 was localized to arterial endothelium using confocal microscopy. IL-1beta increased PGE2 but not PGI2 production and decreased vascular tone as measured in isolated cerebral arteries; the latter effect was partially reversed by treatment with the selective COX-2 inhibitor NS-398 (10 micromol/l). In contrast, in animals treated with estrogen, IL-1beta had no significant effect on COX-2 protein levels, PGE2 production, or vascular tone. Combined treatment with 17beta-estradiol and medroxyprogesterone acetate also prevented increases in PGE2 production after IL-1beta treatment, but treatment with 17alpha-estradiol had no effect. IL-1beta induction of COX-2 protein was prevented by treatment with the nuclear factor-kappaB inhibitor caffeic acid phenethyl ester (20 mg/kg i.p.), and estrogen treatment reduced cerebrovascular nuclear factor-kappaB activity. Estrogen thus has potent anti-inflammatory effects with respect to cerebral vascular responses to IL-1beta. These effects may have important implications for the incidence and severity of cerebrovascular disease.