SPRING HAUL-OUT BEHAVIOR OF RINGED SEALS (PUSA HISPIDA) IN KONGSFJORDEN, SVALBARD

Haul‐out behavior of ringed seals (Pusa hispida) was investigated during the spring molting period of 2003 (May–July) in Kongsfjorden, Svalbard, Norway. Hourly counts were conducted on the land‐fast ice in six spatially defined sectors in the inner fjord, from an elevated land‐based vantage point from early May through until the ice began to break up in June, from 0600 to 2200 daily (total counts n= 478). Concomitantly, measurements were made of a variety of weather parameters. Multiple regression analyses revealed that time of day (P < 0.001) and date (P < 0.001) significantly affected the number of ringed seals hauled out on the ice surface. Other factors influencing the number of seals counted on the ice were air temperature (P= 0.011) and wind speed (P < 0.001). Daily peaks occurred in the early afternoon between 1300 and 1400 and the seasonal high (n= 385) was registered during the first week in June, after which the number of seals on the ice in the fjord declined. In addition to the visual counts, 24 ringed seals were equipped with VHF transmitters, and the haul‐out behavior of individuals was monitored from May through July via an automatic recording station. The VHF‐tagged seals exhibited the same diurnal pattern seen in the total counts, with haul‐out most frequent from 1300 to 1400. Pups exhibited short and frequent haul‐outs, whereas longer haul‐out periods were seen in the older age classes; adult females had the greatest number of haul‐out periods that exceeded 24 h. The seasonal peak of haul‐out for the tagged seals preceded the peak seasonal counts by approximately 3 wk. This may reflect significant out‐ and influx of seals from and to the area, a phenomenon warranting further attention because of its implications for assessment studies.     

Endonuclease G mediates α‐synuclein cytotoxicity during Parkinson's disease

Malfunctioning of the protein α‐synuclein is critically involved in the demise of dopaminergic neurons relevant to Parkinson's disease. Nonetheless, the precise mechanisms explaining this pathogenic neuronal cell death remain elusive. Endonuclease G (EndoG) is a mitochondrially localized nuclease that triggers DNA degradation and cell death upon translocation from mitochondria to the nucleus. Here, we show that EndoG displays cytotoxic nuclear localization in dopaminergic neurons of human Parkinson‐diseased patients, while EndoG depletion largely reduces α‐synuclein‐induced cell death in human neuroblastoma cells. Xenogenic expression of human α‐synuclein in yeast cells triggers mitochondria‐nuclear translocation of EndoG and EndoG‐mediated DNA degradation through a mechanism that requires a functional kynurenine pathway and the permeability transition pore. In nematodes and flies, EndoG is essential for the α‐synuclein‐driven degeneration of dopaminergic neurons. Moreover, the locomotion and survival of α‐synuclein‐expressing flies is compromised, but reinstalled by parallel depletion of EndoG. In sum, we unravel a phylogenetically conserved pathway that involves EndoG as a critical downstream executor of α‐synuclein cytotoxicity.     

A novel rearrangement of occludin causes brain calcification and renal dysfunction

Pediatric intracranial calcification may be caused by inherited or acquired factors. We describe the identification of a novel rearrangement in which a downstream pseudogene translocates into exon 9 of OCLN, resulting in band-like brain calcification and advanced chronic kidney disease in early childhood. SNP genotyping and read-depth variation from whole exome sequencing initially pointed to a mutation in the OCLN gene. The high degree of identity between OCLN and two pseudogenes required a combination of multiplex ligation-dependent probe amplification, PCR, and Sanger sequencing to identify the genomic rearrangement that was the underlying genetic cause of the disease. Mutations in exon 3, or at the 5–6 intron splice site, of OCLN have been reported to cause brain calcification and polymicrogyria with no evidence of extra-cranial phenotypes. Of the OCLN splice variants described, all make use of exon 9, while OCLN variants that use exons 3, 5, and 6 are tissue specific. The genetic rearrangement we identified in exon 9 provides a plausible explanation for the expanded clinical phenotype observed in our individuals. Furthermore, the lack of polymicrogyria associated with the rearrangement of OCLN in our patients extends the range of cranial defects that can be observed due to OCLN mutations.     

Comparative genomics of the core and accessory genomes of 48 Sinorhizobium strains comprising five genospecies

Background

The sinorhizobia are amongst the most well studied members of nitrogen-fixing root nodule bacteria and contribute substantial amounts of fixed nitrogen to the biosphere. While the alfalfa symbiont Sinorhizobium meliloti RM 1021 was one of the first rhizobial strains to be completely sequenced, little information is available about the genomes of this large and diverse species group.

Results

Here we report the draft assembly and annotation of 48 strains of Sinorhizobium comprising five genospecies. While S. meliloti and S. medicae are taxonomically related, they displayed different nodulation patterns on diverse Medicago host plants, and have differences in gene content, including those involved in conjugation and organic sulfur utilization. Genes involved in Nod factor and polysaccharide biosynthesis, denitrification and type III, IV, and VI secretion systems also vary within and between species. Symbiotic phenotyping and mutational analyses indicated that some type IV secretion genes are symbiosis-related and involved in nitrogen fixation efficiency. Moreover, there is a correlation between the presence of type IV secretion systems, heme biosynthesis and microaerobic denitrification genes, and symbiotic efficiency.

Conclusions

Our results suggest that each Sinorhizobium strain uses a slightly different strategy to obtain maximum compatibility with a host plant. This large genome data set provides useful information to better understand the functional features of five Sinorhizobium species, especially compatibility in legume-Sinorhizobium interactions. The diversity of genes present in the accessory genomes of members of this genus indicates that each bacterium has adopted slightly different strategies to interact with diverse plant genera and soil environments.     

Design,synthesis, and bioevaluation of viral 3C and 3C-like protease inhibitors

A class of tripeptidyl transition state inhibitors containing a P1 glutamine surrogate, a P2 leucine, and a P3 arylalanines, was found to potently inhibit Norwalk virus replication in enzyme and cell based assays. An array of warheads, including aldehyde, α-ketoamide, bisulfite adduct, and α-hydroxyphosphonate transition state mimic, was also investigated. Tripeptidyls 2 and 6 possess antiviral activities against noroviruses, human rhinovirus, severe acute respiratory syndrome coronavirus, and coronavirus 229E, suggesting a broad range of antiviral activities.     

A FRET-based assay for the discovery of West Nile Virus NS2B-NS3 protease inhibitors

The West Nile Virus (WNV) has been a worldwide epidemic since the early 1990s. Currently there are no therapeutic treatments for WNV infections. One particular avenue of treatment is inhibition of the NS2B-NS3 protease, an enzyme that is crucial for WNV replication. In our effort to increase the number of NS2B-NS3 protease inhibitors, we report a novel FRET-based high throughput assay for the discovery of WNV NS2B-NS3 protease inhibitors. For this assay, a FRET-based peptide substrate was synthesized and kinetically characterized with the NS2B-NS3 protease. The new substrate exhibits a K_m of 3.35 ± 0.31 μM, a k_cat of 0.0717 ± 0.0016 s^?1 and a k_cat/K_m of 21,400 ± 2000 M^?1 s^?1.     

Fibroblast Growth Factor Receptor 1 Signaling in Adult Cardiomyocytes Increases Contractility and Results in a Hypertrophic Cardiomyopathy

Fibroblast growth factors (FGFs) and their receptors are highly conserved signaling molecules that have been implicated in postnatal cardiac remodeling. However, it is not known whether cardiomyocyte-expressed FGF receptors are necessary or sufficient for ventricular remodeling in the adult heart. To determine whether cardiomyocytes were competent to respond to an activated FGF receptor, and to determine if this signal would result in the development of hypertrophy, we engineered a doxycycline (DOX)-inducible, cardiomyocyte-specific, constitutively active FGF receptor mouse model (αMHC-rtTA, TRE-caFgfr1-myc). Echocardiographic and hemodynamic analysis indicated that acute expression of caFGFR1 rapidly and directly increased cardiac contractility, while chronic expression resulted in significant hypertrophy with preservation of systolic function. Subsequent histologic analysis showed increased cardiomyocyte cross-sectional area and regions of myocyte disarray and fibrosis, classic features of hypertrophic cardiomyopathy (HCM). Analysis of downstream pathways revealed a lack of clear activation of classical FGF-mediated signaling pathways, but did demonstrate a reduction in Serca2 expression and troponin I phosphorylation. Isolated ventricular myocytes showed enhanced contractility and reduced relaxation, an effect that was partially reversed by inhibition of actin-myosin interactions. We conclude that adult cardiomyocytes are competent to transduce FGF signaling and that FGF signaling is sufficient to promote increased cardiomyocyte contractility in vitro and in vivo through enhanced intrinsic actin-myosin interactions. Long-term, FGFR overexpression results in HCM with a dynamic outflow tract obstruction, and may serve as a unique model of HCM.     

Contact Irritant Responses of Aedes aegypti Using Sublethal Concentration and Focal Application of Pyrethroid Chemicals

Background

Previous studies have demonstrated contact irritant and spatial repellent behaviors in Aedes aegypti following exposure to sublethal concentrations of chemicals. These sublethal actions are currently being evaluated in the development of a push-pull strategy for Ae. aegypti control. This study reports on mosquito escape responses after exposure to candidate chemicals for a contact irritant focused push-pull strategy using varying concentrations and focal application.

Methods

Contact irritancy (escape) behavior, knockdown and 24 hour mortality rates were quantified in populations of female Ae. aegypti under laboratory conditions and validated in the field (Thailand and Peru) using experimental huts. Evaluations were conducted using varying concentrations and treatment surface area coverage (SAC) of three pyrethroid insecticides: alphacypermethrin, lambacyhalothrin and deltamethrin.

Results

Under laboratory conditions, exposure of Ae. aegypti to alphacypermethrin using the standard field application rate (FAR) resulted in escape responses at 25% and 50% SAC that were comparable with escape responses at 100% SAC. Significant escape responses were also observed at <100% SAC using ½FAR of all test compounds. In most trials, KD and 24 hour mortality rates were higher in mosquitoes that did not escape than in those that escaped. In Thailand, field validation studies indicated an early time of exit (by four hours) and 40% increase in escape using ½FAR of alphacypermethrin at 75% SAC compared to a matched chemical-free control. In Peru, however, the maximum increase in Ae. aegypti escape from alphacypermethrin-treated huts was 11%.

Conclusions/Significance

Results presented here suggest a potential role for sublethal and focal application of contact irritant chemicals in an Ae. aegypti push-pull strategy to reduce human–vector contact inside treated homes. However, the impact of an increase in escape response on dengue virus transmission is currently unknown and will depend on rate of biting on human hosts prior to house exiting.     

Genome sequence of Frateuria aurantia type strain (Kond? 67T), a xanthomonade isolated from Lilium auratium Lindl.

Frateuria aurantia (ex Kondô and Ameyama 1958) Swings et al. 1980 is a member of the bispecific genus Frateuria in the family Xanthomonadaceae, which is already heavily targeted for non-type strain genome sequencing. Strain Kondô 67^T was initially (1958) identified as a member of ‘Acetobacter aurantius’, a name that was not considered for the approved list. Kondô 67^T was therefore later designated as the type strain of the newly proposed acetogenic species Frateuria aurantia. The strain is of interest because of its triterpenoids (hopane family). F. aurantia Kondô 67^T is the first member of the genus Frateura whose genome sequence has been deciphered, and here we describe the features of this organism, together with the complete genome sequence and annotation. The 3,603,458-bp long chromosome with its 3,200 protein-coding and 88 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.