A powerful system for studying protein aggregation, particularly rapid self-assembly, is spider silk. Spider silks are proteinaceous and silk proteins are synthesized and stored within silk glands as ...liquid dope. As needed, liquid dope is near-instantaneously transformed into solid fibers or viscous adhesives. The dominant constituents of silks are spidroins (spider fibroins) and their terminal domains are vital for the tight control of silk self-assembly. To better understand spidroin termini, we used target capture and deep sequencing to identify spidroin gene sequences from six species representing the araneoid families of Araneidae, Nephilidae, and Theridiidae. We obtained 145 terminal regions, of which 103 are newly annotated here, as well as novel variants within nine diverse spidroin types. Our comparative analyses demonstrated the conservation of acidic, basic, and cysteine amino acid residues across spidroin types that had been proposed to be important for monomer stability, dimer formation, and self-assembly from a limited sampling of spidroins. Computational, protein homology modeling revealed areas of spidroin terminal regions that are highly conserved in three-dimensions despite sequence divergence across spidroin types. Analyses of our dense sampling of terminal regions suggest that most spidroins share stabilization mechanisms, dimer formation, and tertiary structure, despite producing functionally distinct materials.
Spiders in the superfamily Araneoidea produce viscous glue from aggregate silk glands. Aggregate glue coats prey-capture threads and hampers the escape of prey from webs, thereby increasing the ...foraging success of spiders. cDNAs for Aggregate Spider Glue 1 (ASG1) and 2 (ASG2) have been previously described from the golden orb-weaver, Nephila clavipes, and Western black widow, Latrodectus hesperus. To further investigate aggregate glues, we assembled ASG1 and ASG2 from genomic target capture libraries constructed from three species of cob-web weavers and three species of orb-web weavers, all araneoids. We show that ASG1 is unlikely to be a glue, but rather is part of a widespread arthropod gene family, the peritrophic matrix proteins. For ASG2, we demonstrate its remarkable architectural and sequence similarities to spider silk fibroins, indicating that ASG2 is a member of the spidroin gene family. Thus, spidroins have diversified into glues in addition to task-specific, high performance fibers.
Management of postoperative bacterial endophthalmitis was explored in the Endophthalmitis Vitrectomy Study37 in 1995, which has underpinned the core protocols in treatment ever since. While surgical ...techniques have continued to evolve, little has changed in the overall clinical management as no further large randomized controlled trials have taken place. We review the literature addressing the incidence of endophthalmitis, pathogens, antibiotic therapies, and the role of vitrectomy. We suggest an update to management protocols based on available evidence. While vitreous culture remains the gold standard for diagnosis, new techniques allow bacterial identification after antibiotic administration, so injection should be initiated immediately. Current antibiotic regimes are comprehensive and do not need changing. Intravitreal antibiotics should not be repeated at 48 hours after initial treatment. Vitrectomy should be considered instead if the clinical picture is not improving.
Spidroins and Silk Fibers of Aquatic Spiders Correa-Garhwal, Sandra M; Clarke, 3rd, Thomas H; Janssen, Marc ...
Scientific reports,
09/2019, Volume:
9, Issue:
1
Journal Article
Peer reviewed
Open access
Spiders are commonly found in terrestrial environments and many rely heavily on their silks for fitness related tasks such as reproduction and dispersal. Although rare, a few species occupy aquatic ...or semi-aquatic habitats and for them, silk-related specializations are also essential to survive in aquatic environments. Most spider silks studied to date are from cob-web and orb-web weaving species, leaving the silks from many other terrestrial spiders as well as water-associated spiders largely undescribed. Here, we characterize silks from three Dictynoidea species: the aquatic spiders Argyroneta aquatica and Desis marina as well as the terrestrial Badumna longinqua. From silk gland RNA-Seq libraries, we report a total of 47 different homologs of the spidroin (spider fibroin) gene family. Some of these 47 spidroins correspond to known spidroin types (aciniform, ampullate, cribellar, pyriform, and tubuliform), while other spidroins represent novel branches of the spidroin gene family. We also report a hydrophobic amino acid motif (GV) that, to date, is found only in the spidroins of aquatic and semi-aquatic spiders. Comparison of spider silk sequences to the silks from other water-associated arthropods, shows that there is a diversity of strategies to function in aquatic environments.
Summary Background Bevacizumab improves the efficacy of oxaliplatin-based chemotherapy in metastatic colorectal cancer. Our aim was to assess the use of bevacizumab in combination with ...oxaliplatin-based chemotherapy in the adjuvant treatment of patients with resected stage III or high-risk stage II colon carcinoma. Methods Patients from 330 centres in 34 countries were enrolled into this phase 3, open-label randomised trial. Patients with curatively resected stage III or high-risk stage II colon carcinoma were randomly assigned (1:1:1) to receive FOLFOX4 (oxaliplatin 85 mg/m2 , leucovorin 200 mg/m2 , and fluorouracil 400 mg/m2 bolus plus 600 mg/m2 22-h continuous infusion on day 1; leucovorin 200 mg/m2 plus fluorouracil 400 mg/m2 bolus plus 600 mg/m2 22-h continuous infusion on day 2) every 2 weeks for 12 cycles; bevacizumab 5 mg/kg plus FOLFOX4 (every 2 weeks for 12 cycles) followed by bevacizumab monotherapy 7·5 mg/kg every 3 weeks (eight cycles over 24 weeks); or bevacizumab 7·5 mg/kg plus XELOX (oxaliplatin 130 mg/m2 on day 1 every 2 weeks plus oral capecitabine 1000 mg/m2 twice daily on days 1–15) every 3 weeks for eight cycles followed by bevacizumab monotherapy 7·5 mg/kg every 3 weeks (eight cycles over 24 weeks). Block randomisation was done with a central interactive computerised system, stratified by geographic region and disease stage. Surgery with curative intent occurred 4–8 weeks before randomisation. The primary endpoint was disease-free survival, analysed for all randomised patients with stage III disease. This study is registered with ClinicalTrials.gov , number NCT00112918. Findings Of the total intention-to-treat population (n=3451), 2867 patients had stage III disease, of whom 955 were randomly assigned to receive FOLFOX4, 960 to receive bevacizumab–FOLFOX4, and 952 to receive bevacizumab–XELOX. After a median follow-up of 48 months (range 0–66 months), 237 patients (25%) in the FOLFOX4 group, 280 (29%) in the bevacizumab–FOLFOX4 group, and 253 (27%) in the bevacizumab–XELOX group had relapsed, developed a new colon cancer, or died. The disease-free survival hazard ratio for bevacizumab–FOLFOX4 versus FOLFOX4 was 1·17 (95% CI 0·98–1·39; p=0·07), and for bevacizumab–XELOX versus FOLFOX4 was 1·07 (0·90–1·28; p=0·44). After a minimum follow-up of 60 months, the overall survival hazard ratio for bevacizumab–FOLFOX4 versus FOLFOX4 was 1·27 (1·03–1·57; p=0·02), and for bevacizumab–XELOX versus FOLFOX4 was 1·15 (0·93–1·42; p=0·21). The 573 patients with high-risk stage II cancer were included in the safety analysis. The most common grade 3–5 adverse events were neutropenia (FOLFOX4: 477 42% of 1126 patients, bevacizumab-FOLFOX4: 416 36% of 1145 patients, and bevacizumab–XELOX: 74 7% of 1135 patients), diarrhoea (110 10%, 135 12%, and 181 16%, respectively), and hypertension (12 1%, 122 11%, and 116 10%, respectively). Serious adverse events were more common in the bevacizumab groups (bevacizumab–FOLFOX4: 297 26%; bevacizumab–XELOX: 284 25%) than in the FOLFOX4 group (226 20%). Treatment-related deaths were reported in one patient receiving FOLFOX4, two receiving bevacizumab–FOLFOX4, and five receiving bevacizumab–XELOX. Interpretation Bevacizumab does not prolong disease-free survival when added to adjuvant chemotherapy in resected stage III colon cancer. Overall survival data suggest a potential detrimental effect with bevacizumab plus oxaliplatin-based adjuvant therapy in these patients. On the basis of these and other data, we do not recommend the use of bevacizumab in the adjuvant treatment of patients with curatively resected stage III colon cancer. Funding Genentech, Roche, and Chugai.
Most spiders spin multiple types of silk, including silks for reproduction, prey capture, and draglines. Spiders are a megadiverse group and the majority of spider silks remain uncharacterized. For ...example, nothing is known about the silk molecules of Tengella perfuga, a spider that spins sheet webs lined with cribellar silk. Cribellar silk is a type of adhesive capture thread composed of numerous fibrils that originate from a specialized plate-like spinning organ called the cribellum. The predominant components of spider silks are spidroins, members of a protein family synthesized in silk glands. Here, we use silk gland RNA-Seq and cDNA libraries to infer T. perfuga silks at the protein level. We show that T. perfuga spiders express 13 silk transcripts representing at least five categories of spider silk proteins (spidroins). One category is a candidate for cribellar silk and is thus named cribellar spidroin (CrSp). Studies of ontogenetic changes in web construction and spigot morphology in T. perfuga have documented that after sexual maturation, T. perfuga females continue to make capture webs but males halt web maintenance and cease spinning cribellar silk. Consistent with these observations, our candidate CrSp was expressed only in females. The other four spidroin categories correspond to paralogs of aciniform, ampullate, pyriform, and tubuliform spidroins. These spidroins are associated with egg sac and web construction. Except for the tubuliform spidroin, the spidroins from T. perfuga contain novel combinations of amino acid sequence motifs that have not been observed before in these spidroin types. Characterization of T. perfuga silk genes, particularly CrSp, expand the diversity of the spidroin family and inspire new structure/function hypotheses.
Escherichia coli sequence type 131 (ST131) is a globally dominant multidrug-resistant clone, although its clinical impact on patients with bloodstream infection (BSI) is incompletely understood. This ...study aims to further define the risk factors, clinical outcomes, and bacterial genetics associated with ST131 BSI. A prospectively enrolled cohort study of adult inpatients with E. coli BSI was conducted from 2002 to 2015. Whole-genome sequencing was performed with the E. coli isolates. Of the 227 patients with E. coli BSI in this study, 88 (39%) were infected with ST131. Patients with E. coli ST131 BSI and those with non-ST131 BSI did not differ with respect to in-hospital mortality (17/82 20% versus 26/145 18%;
= 0.73). However, in patients with BSI from a urinary tract source, ST131 was associated with a numerically higher in-hospital mortality than patients with non-ST131 BSI (8/42 19% versus 4/63 6%;
= 0.06) and increased mortality in an adjusted analysis (odds ratio of 5.85; 95% confidence interval of 1.44 to 29.49;
= 0.02). Genomic analyses showed that ST131 isolates primarily had an H4:O25 serotype, had a higher number of prophages, and were associated with 11 flexible genomic islands as well as virulence genes involved in adhesion (
,
,
, and
), iron acquisition (
and
), and toxin production (
and
). In patients with E. coli BSI from a urinary tract source, ST131 was associated with increased mortality in an adjusted analysis and contained a distinct repertoire of genes influencing pathogenesis. These genes could contribute to the higher mortality observed in patients with ST131 BSI.
Background:
The predominant species in clinical
Enterobacter
isolates is
E. hormaechei
. Many articles, clinicians, and GenBank submissions misname these strains as
E. cloacae
. The lack of sequenced ...type strains or named species/subspecies for some clades in the
E. cloacae
complex complicate the issue.
Methods:
The genomes of the type strains for
Enterobacter hormaechei
subsp.
oharae
,
E
.
hormaechei
subsp.
steigerwaltii
, and
E. xiangfangensis
, and two strains from Hoffmann clusters III and IV of the
E. cloacae
complex were sequenced. These genomes, the
E
.
hormaechei
subsp.
hormaechei
type strain, and other available
Enterobacter
type strains were analysed in conjunction with all extant
Enterobacter
genomes in NCBI’s RefSeq using Average Nucleotide Identity (ANI).
Results:
There were five recognizable subspecies of
E. hormaechei
:
E. hormaechei
subsp.
hoffmannii
subsp. nov.,
E. hormaechei
subsp.
xiangfangensis
comb. nov., and the three previously known subspecies. One of the strains sequenced from the
E. cloacae
complex was not a novel
E. hormaechei
subspecies but rather a member of a clade of a novel species:
E. roggenkampii
sp. nov..
E. muelleri
was determined to be a later heterotypic synonym of
E. asburiae
which should take precedence.
Conclusion:
The phylogeny of the
Enterobacter
genus, particularly the
cloacae
complex, was re-evaluated based on the type strain genome sequences and all other available
Enterobacter
genomes in RefSeq.
PDF
