Hidden in plain sight: phylogeography of an overlooked parasitoid species Trioxys sunnysidensis Fulbright & Pike (Hymenoptera: Braconidae: Aphidiinae)

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Metabarcoding a diverse arthropod mock community

Although DNA metabarcoding is an attractive approach for monitoring biodiversity, it is often difficult to detect all the species present in a bulk sample. In particular, sequence recovery for a given species depends on its biomass and mitome copy number as well as the primer set employed for PCR. To examine these variables, we constructed a mock community of terrestrial arthropods comprised of 374 species. We used this community to examine how species recovery was impacted when amplicon pools were constructed in four ways. The first two protocols involved the construction of bulk DNA extracts from different body segments (Bulk Abdomen, Bulk Leg). The other protocols involved the production of DNA extracts from single legs which were then merged prior to PCR (Composite Leg) or PCR‐amplified separately (Single Leg) and then pooled. The amplicons generated by these four treatments were then sequenced on three platforms (Illumina MiSeq, Ion Torrent PGM and Ion Torrent S5). The choice of sequencing platform did not substantially influence species recovery, although the Miseq delivered the highest sequence quality. As expected, species recovery was most efficient from the Single Leg treatment because amplicon abundance varied little among taxa. Among the three treatments where PCR occurred after pooling, the Bulk Abdomen treatment produced a more uniform read abundance than the Bulk Leg or Composite Leg treatment. Primer choice also influenced species recovery and evenness. Our results reveal how variation in protocols can have substantial impacts on perceived diversity unless sequencing coverage is sufficient to reach an asymptote.     

Epistatic effects of polymorphisms in genes from the renin-angiotensin, bradykinin, and fibrinolytic systems on plasma t-PA and PAI-1 levels

Tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1) directly influence thrombus formation and degradation and thereby risk for arterial thrombosis. Activation of the renin-angiotensin system has been linked to the production of PAI-1 expression via the angiotensin II type 1 receptor (AT1R). In addition, bradykinin can induce the release of t-PA through a B2 receptor mechanism. In the present study, we aimed to investigate the epistatic effects of polymorphisms in genes from the renin-angiotensin, bradykinin, and fibrinolytic systems on plasma t-PA and PAI-1 levels in a large population-based sample (n=2527). We demonstrated a strong significant interaction within genetic variations of the bradykinin B2 gene (P=0.002) and between ACE and bradykinin B2 (p=0.003) polymorphisms on t-PA levels in females. In males, polymorphisms in the bradykinin B2 and AT1R gene showed the most strong effect on t-PA levels (P=0.006). In both females and males, the bradykinin B2 gene interacted with AT1R gene on plasma PAI-1 levels (P=0.026 and P=0.039, respectively). In addition, the current study found a borderline significant interaction between PAI 4G5G and ACE I/D on plasma t-PA and PAI-1 levels. These results support the idea that the interplay between the renin-angiotensin, bradykinin, and fibrinolytic systems might play an important role in t-PA and PAI-1 biology.     

The structure of membrane associated proteins in eicosanoid and glutathione metabolism as determined by electron crystallography

Membrane associated proteins in eicosanoid and glutathione metabolism (MAPEG) are involved in biosynthesis of arachidonic-derived mediators of pain, fever, and inflammation as well as in biotransformation and detoxification of electrophilic substances. Structure determination of microsomal glutathione transferase 1 using electron crystallography has provided the first atomic model of an MAPEG member. The homotrimer consists of three repeats of a four-helix transmembrane bundle with the largest extramembranous domain connecting the first and second helix and with a short proline rich loop on the same side between helices three and four. Residues of importance for intramolecular or intermolecular contacts as well as for stabilizing the active site have been identified and the results can be applied for interpreting structure-function relationship for similar MAPEG members.     

A New Record of a Host-Parasitoid Interaction: Hymenoepimecis veranii Lofredo & Penteado-Dias, 2009 (Hymenoptera: Ichneumonidae) Parasitizing Araneus orgaos Levi, 1991 (Araneae: Araneidae)

The genus Hymenoepimecis only occurs in the Neotropics. In some species of this genus, the larval stage modifies the behavior of the spider hosts, inducing then to construct a modified web. The wasp Hymenoepimecis veranii has been previously described as an ectoparasitoid of the spider Araneus omnicolor. This study provides detailed information about the natural history of the host-parasitoid interaction involving this wasp with a new host, the spider Araneus orgaos (Araneae: Araneidae), which occurs sympatrically with A. omnicolor.     

Short Daily versus Conventional Hemodialysis for Hypertensive Patients: A Randomized Cross-Over Study

Background

Treatment of end stage renal disease patients with short daily hemodialysis has been associated with an improvement in blood pressure. It is unclear from these studies if anti-hypertensive management had been optimized prior to starting short daily hemodialysis. Also, the potential mechanism(s) of blood pressure improvement remain to be fully elucidated.

Study Design, Setting and Participants

We undertook a randomized cross-over trial in adult hypertensive patients with ESRD treated with conventional hemodialysis to determine: 1) if short-daily hemodialysis is associated with a reduction in systolic blood pressure after a 3-month blood pressure optimization period and; 2) the potential mechanism(s) of blood pressure reduction. Blood pressure was measured using Canadian Hypertension Education Program guidelines. Extracellular fluid volume (ECFV) was assessed with bioimpedance. Serum catecholamines were used to assess the sympathetic nervous system. Interleukin-6 (IL-6) and thiobarbituric acid reactive substances (T-BARS) were used as markers of inflammation and oxidative stress respectively.

Results

After a 3-month run-in phase in which systolic blood pressure improved, there was no significant difference in pre-dialysis systolic pressure between short-daily and conventional hemodialysis (p = 0.39). However, similar blood pressures were achieved on fewer anti-hypertensive medications with short daily hemodialysis compared to conventional hemodialysis (p = 0.01). Short daily hemodialysis, compared to conventional hemodialysis, was not associated with a difference in dry weight or ECFV (p = 0.77). Sympathetic nervous system activity as assessed by plasma epinephrine (p = 1.0) and norepinephrine (p = 0.52) was also not different. Markers of inflammation (p = 0.42) and oxidative stress (p = 0.83) were also similar between the two treatment arms.

Conclusions

Patients treated with short daily, compared to conventional hemodialysis, have similar blood pressure control on fewer anti-hypertensive medications. The mechanism(s) by which short daily hemodialysis allows for decreased anti-hypertensive medication use remains unclear but effects on sodium balance and changes in peripheral vascular resistance require further study.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00759967","term_id":"NCT00759967"}}NCT00759967     

DNA Barcodes for Nearctic Auchenorrhyncha (Insecta: Hemiptera)

Background

Many studies have shown the suitability of sequence variation in the 5′ region of the mitochondrial cytochrome c oxidase I (COI) gene as a DNA barcode for the identification of species in a wide range of animal groups. We examined 471 species in 147 genera of Hemiptera: Auchenorrhyncha drawn from specimens in the Canadian National Collection of Insects to assess the effectiveness of DNA barcoding in this group.

Methodology/Principal Findings

Analysis of the COI gene revealed less than 2% intra-specific divergence in 93% of the taxa examined, while minimum interspecific distances exceeded 2% in 70% of congeneric species pairs. Although most species are characterized by a distinct sequence cluster, sequences for members of many groups of closely related species either shared sequences or showed close similarity, with 25% of species separated from their nearest neighbor by less than 1%.

Conclusions/Significance

This study, although preliminary, provides DNA barcodes for about 8% of the species of this hemipteran suborder found in North America north of Mexico. Barcodes can enable the identification of many species of Auchenorrhyncha, but members of some species groups cannot be discriminated. Future use of DNA barcodes in regulatory, pest management, and environmental applications will be possible as the barcode library for Auchenorrhyncha expands to include more species and broader geographic coverage.     

Taste of a Pill: ORGANIC CATION TRANSPORTER-3 (OCT3) MEDIATES METFORMIN ACCUMULATION AND SECRETION IN SALIVARY GLANDS*

Drug-induced taste disturbance is a common adverse drug reaction often triggered by drug secretion into saliva. Very little is known regarding the molecular mechanisms underlying salivary gland transport of xenobiotics, and most drugs are assumed to enter saliva by passive diffusion. In this study, we demonstrate that salivary glands selectively and highly express OCT3 (organic cation transporter-3), a polyspecific drug transporter in the solute carrier 22 family. OCT3 protein is localized at both basolateral (blood-facing) and apical (saliva-facing) membranes of salivary gland acinar cells, suggesting a dual role of this transporter in mediating both epithelial uptake and efflux of organic cations in the secretory cells of salivary glands. Metformin, a widely used anti-diabetic drug known to induce taste disturbance, is transported by OCT3/Oct3 in vitro. In vivo, metformin was actively transported with a high level of accumulation in the salivary glands of wild-type mice. In contrast, active uptake and accumulation of metformin in salivary glands were abolished in Oct3^−/− mice. Oct3^−/− mice also showed altered metformin pharmacokinetics and reduced drug exposure in the heart. These results demonstrate that OCT3 is responsible for metformin accumulation and secretion in salivary glands. Our study uncovered a novel carrier-mediated pathway for drug entry into saliva and sheds new light on the molecular mechanisms underlying drug-induced taste disorders.