Molecular detection of type II polyketide synthase genes in Cuban soils

Molecular detection methods were developed to study the distribution of type II polyketide synthase (PKS) genes in Cuban soils. A PCR based detection method targeting the α and β ketosynthase genes was applied to a number of different total community DNA samples. These genes were detected in 43% of samples tested from a number of different locations. A botanical garden site located in Havana, Cuba, was found to show the greatest distribution of type II PKS genes across the sites tested. It was not possible to amplify type II PKS genes from a pristine island site off the coast of Cuba. Further investigation revealed that actinornycetes containing type II PKS were present in the soil community at a level above the detection limit of the PCR protocol. Further total community DNA cleanup steps failed to allow the detection of type II PKS genes within the DNA samples suggesting PCR inhibition was responsible for negative results. The molecular detection of type II PKS genes in total community DNA was compared to the detection of type II PKS genes in actinomycete isolates. A lack of correlation between these two approaches was observed with the molecular detection limit unable to amplify type II PKS genes in <50% of crop soils tested. Actinomycetes containing type II PKS genes could be isolated from all crop soils tested. No difference was seen in the detection of type II PKS genes between rhizosphere and bulk soil samples. Actinomycetes were isolated using a selective isolation procedure at a level of approximately 10(7) cfu g-1 soil compared to 10(8) cfu g-1 for total bacterial counts. Actinomycetes were isolated from Cuban crop soils and screened for the presence of type II PKS genes. Out of 100 isolates 26 were found to contain the genes of interest. Phylogenetic analysis of these isolates based on 16S rDNA and recA sequence data showed them to be closely grouped within the streptomycetes. Sequence data based on KSα genes from Cuban isolates showed them to be representative of both spore pigment and antibiotic polyketide genes. A representative clone library was constructed containing type II PKS genes amplified from total community DNA. Rhizosphere and bulk soil samples were compared from the same site. Sequences obtained from rhizosphere total community DNA appeared to be widely distributed when compared to published sequences and included examples of both spore pigment and antibiotic polyketide genes. A molecular method was developed to amplify near full length α and β KS genes from type II PKS gene clusters. Expression vectors were constructed to allow these genes to be expressed along with an ACP to give a functional minimal PKS for polyketide chain production. This method was used on total community DNA in an attempt to extract diverse genes from as yet uncultured organisms

The antigenic properties of synthetic gelatin compounds

Thesis (M.A.)--Boston University, 1935. This item was digitized by the Internet Archive

Impaired thermoregulatory function during dynamic exercise in multiple sclerosis

INTRODUCTION: Impairments in sudomotor function during passive whole-body heating have been reported in multiple sclerosis (MS), a demyelinating disease of the CNS that disrupts autonomic function. However, the capability of the thermoregulatory system to control body temperature during exercise has never been assessed in MS. Thus, the aim of the present study was to test the hypothesis that thermoregulatory function is impaired in MS patients compared to healthy controls (CON) exercising at similar rates of metabolic heat production. METHODS: Sweating and skin blood flow responses were compared between 12 individuals diagnosed with relapsing-remitting MS (9 females, 3 males) and 12 sex-, age-, mass- and BSA-matched healthy controls during a single bout of cycling exercise (rate of metabolic heat production: ~4.5 W/kg) for 60 min in a climate-controlled room (25 °C, 30% RH). RESULTS: Individuals with MS exhibited an attenuated increase in cumulative whole-body sweat loss after 30 min (MS: 72 ± 51; CON: 104 ± 37 g, p=0.04) and 60 min (MS: 209 ± 94; CON: 285 ± 62 g, p=0.02), as well as lower sweating thermosensitivity (MS: 0.49 ± 0.26; CON: 0.86 ± 0.30 mg/cm2/min/°C, p=0.049). Despite evidence for thermoregulatory dysfunction, there were no differences between MS and CON in esophageal or rectal temperatures at 30 or 60 min time points (p>0.05). Cutaneous vasculature responses were also not different in MS compared to CON (p>0.05). CONCLUSION: Taken together, MS blunts sweating responses during exercise while cutaneous vasculature responses are preserved. Altered mechanisms of body temperature regulation in persons with MS may lead to temporary worsening of disease symptoms and limit exercise tolerance under more thermally challenging conditions.Accepted manuscrip

KINETIC ANALYSES OF TWO FENCING ATTACKS – LUNGE AND FLECHE

Two fencing attacks – the lunge and the fleche – were investigated to determine the moments and powers of the joints of the lower extremity. A Vicon MX system recorded the motion while four force platforms simultaneously recorded the ground reaction forces. Inverse dynamics was used to calculate the moments and powers produced at the hip, knees and ankles of both legs. Results showed that during the lunge, the commonest attack, only the trail leg’s extensors and hip abductors contributed significantly to the attack. On the other hand, for the more dynamic and risky fleche, extensors of the ankle, knee and hip and the hip abductors for both legs contributed significantly to the attack

Discovery of low-metallicity stars in the central parsec of the Milky Way

We present a metallicity analysis of 83 late-type giants within the central 1 pc of the Milky Way. K-band spectroscopy of these stars were obtained with the medium-spectral resolution integral-field spectrograph NIFS on Gemini North using laser-guide star adaptive optics. Using spectral template fitting with the MARCS synthetic spectral grid, we find that there is large variation in metallicity, with stars ranging from [M/H] $<$ -1.0 to above solar metallicity. About 6\% of the stars have [M/H] $<$ -0.5. This result is in contrast to previous observations, with smaller samples, that show stars at the Galactic center have approximately solar metallicity with only small variations. Our current measurement uncertainties are dominated by systematics in the model, especially at [M/H] $>$ 0, where there are stellar lines not represented in the model. However, the conclusion that there are low metallicity stars, as well as large variations in metallicity is robust. The metallicity may be an indicator of the origin of these stars. The low-metallicity population is consistent with that of globular clusters in the Milky Way, but their small fraction likely means that globular cluster infall is not the dominant mechanism for forming the Milky Way nuclear star cluster. The majority of stars are at or above solar metallicity, which suggests they were formed closer to the Galactic center or from the disk. In addition, our results indicate that it will be important for star formation history analyses using red giants at the Galactic center to consider the effect of varying metallicity.Comment: 11 pages, 10 figures, ApJ Accepte

City People: City centre living in the UK

City People examines the size and nature of the city centre living phenomenon, focusing on the historic cores of Dundee, Liverpool and Manchester. It asks why it has happened, who is living in the heart of the city - and how long they plan to stay. It then assesses the economic and social benefits of city centre living