1,151 research outputs found
Draft Genome Sequence of Vibrio coralliilyticus strain OCN008 Isolated from Kāneʻohe Bay, Hawaiʻi.
Vibrio coralliilyticus is a Gram-negative bacterium found in seawater and is associated with diseased marine organisms. Strains
of V. coralliilyticus have been shown to infect coral from multiple genera. We report the draft genome sequence of V. coralliilyticus strain OCN008, the third V. coralliilyticus genome to be sequenced
ABC Transporter Required for Intercellular Transfer of Developmental Signals in a Heterocystous Cyanobacterium
In the filamentous cyanobacterium Anabaena, patS and hetN encode peptide-derived signals with many of the properties of
morphogens. These signals regulate the formation of a periodic pattern of heterocysts by lateral inhibition of differentiation.
Here we show that intercellular transfer of the patS- and hetN-dependent developmental signals from heterocysts to vegetative cells requires HetC, a predicted ATP-binding cassette transporter (ABC transporter). Relative to the wild type, in a hetC mutant differentiation resulted in a reduced number of heterocysts that were incapable of nitrogen fixation, but deletion of patS or hetN restored heterocyst number and function in a hetC background. These epistasis results suggest that HetC is necessary for conferring self-immunity to the inhibitors on differentiating cells. Nine hours after induction of differentiation, HetC was required for neither induction of transcription of patS nor intercellular transfer of the patS-encoded signal to neighboring cells. Conversely, in strains lacking HetC, the patS- and hetN-encoded signals were not transferred from heterocyst cells to adjacent vegetative cells. The results support a model in which the patS-dependent signal is initially transferred between vegetative cells in a HetC-independent fashion, but some time before morphological differentiation of heterocysts is complete, transfer of both signals transitions to a HetC-dependent process
Assessment of disease lesion removal as a method to control chronic Montipora white syndrome
Coral colonies in Ka–ne‘ohe Bay, Hawai‘i (USA), are afflicted with the tissue loss disease chronic Montipora white syndrome (cMWS). Here we show that removal of chronic disease lesions is a potential method to slow the progression of cMWS in M. capitata. Over the 24 wk observation period, treatment colonies lost almost half the amount of tissue that was lost by control colonies. The percentage of tissue loss at each sampling interval (mean ± SEM; treatment: 1.17 ± 0.47%, control: 2.25 ± 0.63%) and the rate of tissue loss per day (treatment: 0.13 ± 0.04%, control: 0.27 ± 0.08%) were both significantly lower on treated colonies than control colonies. While lesion removal stopped tissue loss at the initial infection site, which allowed colony healing, it did not prevent re-infection; in all but one of the treated colonies, new cMWS lesions appeared in other areas of the colony but not around the treatment margins. Additionally, the rate of new infections was similar between treatment and control colonies, indicating that physical injury from lesion removal did not appear to increase cMWS susceptibility. These results indicate that lesion removal reduced morbidity in M. capitata exhibiting cMWS but did not stop the disease
The hetZ Gene Regulates Heterocyst Formation in Anabaena sp. strain PCC 7120
To form a complex multicellular organism, stem cells must differentiate into each cell/tissue type along proper spatiotemporal scales. The study of differentiation and organismal development has historically been conducted in prokaryotes due to their genetic and morphological simplicity. Anabaena sp. strain PCC 7120 is a multicellular filamentous cyanobacterium that differentiates a morphologically distinct secondary cell type, the heterocyst, in response to a lack of combined environmental nitrogen. Heterocysts are regularly spaced along filaments and fix atmospheric dinitrogen to maintain organismal viability in its absence. Previous work suggested that the hetZ gene is involved in heterocyst differentiation, but the insertional mutants created produced inconsistent phenotypes, so a specific role was not assigned. In this work, a clean hetZ mutant incapable of heterocyst differentiation was generated and the mutation was complemented with the reintroduction of hetZ alone. Overexpression of hetZ bypassed a mutation of hetR, the master regulator of heterocyst differentiation that controls biological pattern formation, but not a mutation of hetP, a regulator of commitment to a differentiated cell fate, which places hetZ roughly between these processes. A protein-protein interaction study showed that HetZ interacts with both HetR and itself. Assessment of transcriptional fusions between the hetZ, hetR, hetP, and patS (an inhibitor of HetR) promoter regions and GFP, and overexpression of HetR in a hetZ mutant resulted in the differentiation of heterocyst-like cells, together indicated that HetZ may act in concert with HetR as an early regulator of development. Taken together, these data describe a non-linear pathway of regulation leading to heterocyst development governed by both HetR and HetZ
Analysis of VVEPFL9-1 and VVEPFL9-2 expression in grapevine leaves and correlation with stomatal density
Complete Genome Sequence of Pseudoalteromonas sp. Strain OCN003, Isolated from Kāneʻohe Bay, Oʻahu, Hawaii
Pseudoalteromonas sp. strain OCN003 is a marine gammaproteobacterium that was isolated from a diseased colony of the common Hawaiian reef coral, Montipora capitata, found on a reef surrounding Moku o Loʻe in Kāneʻohe Bay, Hawaii. Here, we report the complete genome of Pseudoalteromonas sp. strain OCN003
Complete Genome Sequence of Vibrio coralliilyticus Strain OCN014, Isolated from a Diseased Coral at Palmyra Atoll
Vibrio coralliilyticus is a marine gammaproteobacterium that has been implicated as an etiological agent of disease for multiple
coral genera on reefs worldwide. We report the complete genome of V. coralliilyticus strain OCN014, isolated from a diseased
Acropora cytherea colony off the western reef terrace of Palmyra Atoll
First Record of Black Band Disease in the Hawaiian Archipelago: Response, Outbreak Status, Virulence, and a Method of Treatment
A high number of coral colonies, Montipora spp., with progressive tissue loss were reported
from the north shore of Kaua‘i by a member of the Eyes of the Reef volunteer reporting network.
The disease has a distinct lesion (semi-circular pattern of tissue loss with an adjacent
dark band) that was first observed in Hanalei Bay, Kaua‘i in 2004. The disease, initially
termed Montipora banded tissue loss, appeared grossly similar to black band disease
(BBD), which affects corals worldwide. Following the initial report, a rapid response was initiated
as outlined in Hawai‘i’s rapid response contingency plan to determine outbreak status
and investigate the disease. Our study identified the three dominant bacterial constituents
indicative of BBD (filamentous cyanobacteria, sulfate-reducing bacteria, sulfide-oxidizing
bacteria) in coral disease lesions from Kaua‘i, which provided the first evidence of BBD in
the Hawaiian archipelago. A rapid survey at the alleged outbreak site found disease to affect
6-7% of the montiporids, which is higher than a prior prevalence of less than 1% measured
on Kaua‘i in 2004, indicative of an epizootic. Tagged colonies with BBD had an
average rate of tissue loss of 5.7 cm2/day over a two-month period. Treatment of diseased
colonies with a double band of marine epoxy, mixed with chlorine powder, effectively reduced
colony mortality. Within two months, treated colonies lost an average of 30% less tissue
compared to untreated controls
Pseudoalteromonas piratica sp. nov., a budding, prosthecate bacterium from diseased Montipora capitata, and emended description of the genus Pseudoalteromonas
A Gram-stain-negative, motile, rod-shaped bacterium designated OCN003T was cultivated from mucus taken from a diseased colony of the coral Montipora capitata in Kāne‘ohe Bay, O‘ahu, Hawai‘i. Colonies of OCN003T were pale yellow, 1–3 mm in diameter, convex, smooth and entire. The strain was heterotrophic, strictly aerobic and strictly halophilic. Cells of OCN003T produced buds on peritrichous prosthecae. Growth occurred within the pH range of 5.5 to 10, and the temperature range of 14 to 39 °C. Major fatty acids were 16 : 1!7c, 16 : 0, 18 : 1!7c, 17 : 1!8c, 12 : 0 3-OH and 17 : 0. Phylogenetic analysis of 1399 nucleotides of the 16S rRNA gene nucleotide sequence and a multi-locus sequence analysis of three genes placed OCN003T in the genus Pseudoalteromonas and indicated that the nearest relatives described are Pseudoalteromonas spongiae, P. luteoviolacea, P. ruthenica and P. phenolica (97–99 % sequence identity). The DNA G+C content of the strain’s genome was 40.0 mol%. Based on in silico DNA–DNA hybridization and phenotypic differences from related type strains, we propose that OCN003T represents the type strain of a novel species in the genus Pseudoalteromonas, proposed as Pseudoalteromonas piratica sp. nov. OCN003T (=CCOS1042T =CIP 111189T ). An emended description of the genus Pseudoalteromonas is presented
Expanding the Direct HetR Regulon in Anabaena sp. Strain PCC 7120
In response to a lack of environmental combined nitrogen, the filamentous cyanobacterium Anabaena sp. strain PCC 7120 differentiates nitrogen-fixing heterocyst cells in a periodic pattern. HetR is a transcription factor that coordinates the regulation of this developmental program. An inverted repeat-containing sequence in the hepA promoter required for proheterocyst-specific transcription was identified based on sequence similarity to a previously characterized binding site for HetR in the promoter of hetP. The binding affinity of HetR for the hepA site is roughly an order of magnitude lower than that for the hetP binding site. A BLAST search of the Anabaena genome identified 166 hepA-like sites that occur as single or tandem sites (two binding sites separated by 13 bp). The vast majority of these sites are present in predicted intergenic regions. HetR bound five representative single binding sites in vitro, and binding was abrogated by transversions in the binding sites that conserved the inverted repeat nature of the sites. Binding to four representative tandem sites was not observed. Transcriptional fusions of the green fluorescent protein gene gfp with putative promoter regions associated with the representative binding sites indicated that HetR could function as either an activator or repressor and that activation was cell-type specific. Taken together, we have expanded the direct HetR regulon and propose a model in which three categories of HetR binding sites, based on binding affinity and nucleotide sequence, contribute to three of the four phases of differentiation
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