Relationship of alcohol production to lipid composition of yeast in a continuous flow bioreactor

Saccharomyces cerevisiae was cultivated in a controlled aerated, dual-stage (column), continuous flow bioreactor in a hybrid free-cell and immobilized-cell state. The yeast cells maintained an ethanol concentration of 58-64 and 91-98 g/L in stages I and II, respectively. The lipid composition of the cells cultivated under these conditions was correlated to the effects of aeration by interrupting the aeration on days 113 and 266 of continuous operation. Under conditions of aeration or nonaeration, an alternating increase and decrease in the contents of squalene, sterols, and fatty acids of the respiratory-competent and -deficient unattached free cells was observed. The cellular free lipid compositions of the immobilized cells in the aerated and nonaerated conditions were similar and characteristic of respiratory-deficient cells with the exception of the immobilized cells exposed to a higher ethanol concentration (stage II). These cells contained a broader range of sterol components and increased levels of unsaturated fatty acids than immobilized cells at a lower ethanol concentration (stage I). The neutral lipid to phospholipid ratio decreased for respiratory-deficient cells with phosphatidylethanolamine and phosphatidylinositol being the principal phospholipids. The data demonstrated the essentiality of the hybrid bioreactor design for continuous long term performance and the importance of maintaining specific yeast lipid constituents for continuous high alcohol productivity.     

Occurrence of squalene, di- and tetrahydrosqualenes, and vitamin MK8 in an extremely halophilic bacterium, Halobacterium cutirubrun

The nonpolar (acetone-soluble) lipids of the extremely halophilic bacterium, Halobacterium cutirubrum, were found to consist of red carotenoid pigments (43%) and squalenes (48%) with a small amount of a vitamin K-type quinone. The squalenes were shown by n.m.r. and mass spectra to consist of the fully isoprenoid squalene (S; C(30)H(50)), dihydrosqualene (S(2); C(30)H(52)), and tetrahydrosqualene (S(4); C(30)H(54)) in the ratio of 1.0:0.4:0.1. S(2) probably has one reduced internal isoprenoid group, and S(4) has one internal and one terminal reduced isoprenyl group. The vitamin K-type quinone was shown by n.m.r. and mass spectra to have a C(40) isoprenoid side chain, and is thus identified as menaquinone-8 (MK-8).     

Phytanyl-glycerol ethers and squalenes in the archaebacteriumMethanobacterium thermoautotrophicum

Summary The lipids of a thermophilic chemolithotroph,Metbanobacterium thermoautotropbicum, have been analyzed by chromatographic techniques and identified by infrared spectrometry and combined gas chromatography-mass spectrometry. Of the total chloroform soluble lipids 79% and 21% are polar and non-polar lipids, respectively. The major components of the polar lipids are dialkyl ethers of glycerol or its derivatives. The nature of the glycerol ether alkyl groups was found to be that of the saturated tetraisoprenoid hydrocarbon phytane. The non-polar lipids of the chloroform soluble fraction consist principally of three series of C₂₀, C₂₅ and C₃₀ acyclic isoprenoid hydrocarbons, the major components being squalene and a continuous range of hydrosqualene derivatives, from dihydrosqualene up to and including decahydrosqualene. These data establish thatM. tbermoautotropbicum contains predominantly non-sapo-nifiable lipids as doHalobacterium, Halococcus, Sulfolobus andTbermoplasma. In particular, the composition of the chloroform soluble lipids ofM. tbermoautotropbicum is quite similar to that ofHalobacterium cutirubrum. The results strongly support the recent proposal, based on 16S rRNA sequence homologies, that the extreme halophiles and methanogens share a common ancestor. In addition, it is pointed out that the occurrence of phytane and related polyisoprenoid compounds in ancient sediments can no longer be considered unequivocally as indicative of past photosynthetic activity. Finally, speculations are made concerning the possible role of and evolutionary significance of the presence of squalene and hydrosqualenes in these organisms. To our knowledge this is the first report of squalene and hydrosqualenes in a strictly anaerobic microorganism.To either of whom reprint requests should be sent.     

Non-aerated cultivation ofHalobacterium cutirubrum and its effect on cellular squalenes

Summary Halobacterium cutirubrum was successfully cultivated under aerobic and microaerobic conditions. The early stationary phase of growth was obtained at 2.2 days and 45–55 days for aerated and non-aerated cultures, respectively. The dry cell yields were 0.7–1.2 gm/l in all preparations grown to early stationary growth phase. The cellular ratio of squalene to dihydro- and tetra-hydrosqualene decreased proportionately with decreased aeration rates.     

Evolution of microhabitat association and morphology in a diverse group of cryptobenthic coral reef fishes (Teleostei: Gobiidae: Eviota)

Gobies (Teleostei: Gobiidae) are an extremely diverse and widely distributed group and are the second most species rich family of vertebrates. Ecological drivers are key to the evolutionary success of the Gobiidae. However, ecological and phylogenetic data are lacking for many diverse genera of gobies. Our study investigated the evolution of microhabitat association across the phylogeny of 18 species of dwarfgobies (genus Eviota), an abundant and diverse group of coral reef fishes. In addition, we also explore the evolution of pectoral fin-ray branching and sensory head pores to determine the relationship between morphological evolution and microhabitat shifts. Our results demonstrate that Eviota species switched multiple times from a facultative hard-coral association to inhabiting rubble or mixed sand/rubble habitat. We found no obvious relationship between microhabitat shifts and changes in pectoral fin-ray branching or reduction in sensory pores, with the latter character being highly homoplasious throughout the genus. The relative flexibility in coral-association in Eviota combined with the ability to move into non-coral habitats suggests a genetic capacity for ecological release in contrast to the strict obligate coral-dwelling relationship commonly observed in closely related coral gobies, thus promoting co-existence through fine scale niche partitioning. The variation in microhabitat association may facilitate opportunistic ecological speciation, and species persistence in the face of environmental change. This increased speciation opportunity, in concert with a high resilience to extinction, may explain the exceptionally high diversity seen in Eviota compared to related genera in the family.     

Gobies are deeply divided: phylogenetic evidence from nuclear DNA (Teleostei: Gobioidei: Gobiidae)

Gobies (Gobiidae sensu Gill & Mooi, 2012 Gill, A. and Mooi, R. 2012. Thalasseleotrididae, new family of marine gobioid fishes from New Zealand and temperate Australia, with a revised definition of its sister taxon, the Gobiidae (Teleostei: Acanthomorpha). Zootaxa, 3266: 41–52.  [Google Scholar]) are one of the most diverse families of vertebrates, and comprise over 1700 species of marine, brackish and freshwater fishes. Phylogenetic studies based on morphological characters and mtDNA have suggested that goby diversity is asymmetrically split between a speciose clade of predominantly marine species, and a less rich, but ecologically diverse, clade comprising predominantly freshwater and brackish species. This study is the first to explore this deep divide in gobies and their relationships at the family level using phylogenetic data from nuclear genes (RAG1, rhodopsin). Our results confirm the split within the Gobiidae, and agree with prior molecular studies on the inclusion of the following taxa within the two goby clades: (i) the more diverse of the two clades of gobies (the ‘Gobiidae’ sensu stricto of Thacker 2009 Thacker, C. E. 2009. Phylogeny of Gobioidei and placement within Acanthomorpha, with a new classification and investigation of diversification and character evolution. Copeia, 1: 93–104. doi:10.1643/CI-08-004[Crossref], [Web of Science ®] , [Google Scholar]) comprises the gobiines, microdesmines, ptereleotrines and kraemeriines; (ii) the less diverse of the two gobiid clades (‘Gobionellidae’ sensu Thacker 2009 Thacker, C. E. 2009. Phylogeny of Gobioidei and placement within Acanthomorpha, with a new classification and investigation of diversification and character evolution. Copeia, 1: 93–104. doi:10.1643/CI-08-004[Crossref], [Web of Science ®] , [Google Scholar]) includes the gobionellines, oxudercines, amblyopines, sicydiines, as well as the European sand gobies. Some relationships within the two major gobiid clades remain unclear. Specifically, there remains confusion regarding the monophyly and interrelationships between the northern Pacific gobionellines, the Mugilogobius group gobionellines, and the European sand gobies. Additionally, within Thacker's (2009 Thacker, C. E. 2009. Phylogeny of Gobioidei and placement within Acanthomorpha, with a new classification and investigation of diversification and character evolution. Copeia, 1: 93–104. doi:10.1643/CI-08-004[Crossref], [Web of Science ®] , [Google Scholar]) Gobiidae sensu stricto, there are several well-supported groups (e.g. the wormfishes and dartfishes, the Coral Gobies, the Gobiosomatini), yet relationships among these groups are still poorly resolved despite the use of data from two conserved nuclear genes. Future phylogenetic analyses of gobies will benefit greatly from taxon sampling that includes groups that have been historically under-represented in molecular studies (e.g. European sand gobies, northern Pacific gobionellines, African species), as well as deeper genetic sampling including large numbers of independent loci from throughout the genome (i.e. a phylogenomic approach).     

<Emphasis Type="Italic">Burkholderia</Emphasis> Hep_Hag autotransporter (BuHA) proteins elicit a strong antibody response during experimental glanders but not human melioidosis

Background  

The bacterial biothreat agents Burkholderia mallei and Burkholderia pseudomallei are the cause of glanders and melioidosis, respectively. Genomic and epidemiological studies have shown that B. mallei is a recently emerged, host restricted clone of B. pseudomallei.     

Bone formation rather than inflammation reflects Ankylosing Spondylitis activity on PET-CT: a pilot study

Introduction

Positron Emission Tomography - Computer Tomography (PET-CT) is an interesting imaging technique to visualize Ankylosing Spondylitis (AS) activity using specific PET tracers. Previous studies have shown that the PET tracers [¹⁸F]FDG and [¹¹C](R)PK11195 can target inflammation (synovitis) in rheumatoid arthritis (RA) and may therefore be useful in AS. Another interesting tracer for AS is [¹⁸F]Fluoride, which targets bone formation. In a pilot setting, the potential of PET-CT in imaging AS activity was tested using different tracers, with Magnetic Resonance Imaging (MRI) and conventional radiographs as reference.

Methods

In a stepwise approach different PET tracers were investigated. First, whole body [¹⁸F]FDG and [¹¹C](R)PK11195 PET-CT scans were obtained of ten AS patients fulfilling the modified New York criteria. According to the BASDAI five of these patients had low and five had high disease activity. Secondly, an extra PET-CT scan using [¹⁸F]Fluoride was made of two additional AS patients with high disease activity. MRI scans of the total spine and sacroiliac joints were performed, and conventional radiographs of the total spine and sacroiliac joints were available for all patients. Scans and radiographs were visually scored by two observers blinded for clinical data.

Results

No increased [¹⁸F]FDG and [¹¹C](R)PK11195 uptake was noticed on PET-CT scans of the first 10 patients. In contrast, MRI demonstrated a total of five bone edema lesions in three out of 10 patients. In the two additional AS patients scanned with [¹⁸F]Fluoride PET-CT, [¹⁸F]Fluoride depicted 17 regions with increased uptake in both vertebral column and sacroiliac joints. In contrast, [¹⁸F]FDG depicted only three lesions, with an uptake of five times lower compared to [¹⁸F]Fluoride, and again no [¹¹C](R)PK11195 positive lesions were found. In these two patients, MRI detected nine lesions and six out of nine matched with the anatomical position of [¹⁸F]Fluoride uptake. Conventional radiographs showed structural bony changes in 11 out of 17 [¹⁸F]Fluoride PET positive lesions.

Conclusions

Our PET-CT data suggest that AS activity is reflected by bone activity (formation) rather than inflammation. The results also show the potential value of PET-CT for imaging AS activity using the bone tracer [¹⁸F]Fluoride. In contrast to active RA, inflammation tracers [¹⁸F]FDG and [¹¹C](R)PK11195 appeared to be less useful for AS imaging.     

The influence of landscape and environmental factors on ranavirus epidemiology in a California amphibian assemblage

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Repeated invasions into the twilight zone: evolutionary origins of a novel assemblage of fishes from deep Caribbean reefs

Mesophotic and deeper reefs of the tropics are poorly known and underexplored ecosystems worldwide. Collectively referred to as the ‘twilight zone’, depths below ~30–50 m are home to many species of reef fishes that are absent from shallower depths, including many undescribed and endemic species. We currently lack even a basic understanding of the diversity and evolutionary origins of fishes on tropical mesophotic reefs. Recent submersible collections in the Caribbean have provided new specimens that are enabling phylogenetic reconstructions that incorporate deep‐reef representatives of tropical fish genera. Here, we investigate evolutionary depth transitions in the family Gobiidae (gobies), the most diverse group of tropical marine fishes. Using divergence‐time estimation coupled with stochastic character mapping to infer the timing of shallow‐to‐deep habitat transitions in gobies, we demonstrate at least four transitions from shallow to mesophotic depths. Habitat transitions occurred in two broad time periods (Miocene, Pliocene–Pleistocene), and may have been linked to the availability of underutilized niches, as well as the evolution of morphological/behavioural adaptations for life on deep reefs. Further, our analysis shows that at least three evolutionary lineages that invaded deep habitats subsequently underwent speciation, reflecting another unique mode of radiation within the Gobiidae. Lastly, we synthesize depth distributions for 95 species of Caribbean gobies, which reveal major bathymetric faunal breaks at the boundary between euphotic and mesophotic reefs. Ultimately, our study is the first rigorous investigation into the origin of Caribbean deep‐reef fishes and provides a framework for future studies that utilize rare, deep‐reef specimens.