538 research outputs found
Practical manual for studies of Environmental Physiology and Biochemistry of culturable Marine Organisms
For the applied biologist interested in mariculture, choosing
the 'right' organism may mean the difference between success and
failure. Generally decisions require a compromise between ease of
handling (a function of how much has already been done by others)
and desirability of the cultured product. In the Cochin area of
India, the use of mullet, milkfish and Tilapia for mariculture, for
example, represents such a compromise, which is evidently effective,
presumably in large part because of the years of experience and
data which have gradually accumulated on these species. However
successful such choices may be, they should not rule out a
continuous search for other, perhaps more advantageous, species:
ones which are more hardy, grow faster, sell faster and taste better
Theorems of environmental adaptation
Organisms are perpetually buffetted by the external environment,
yet of course somehow manage its effects. In ectothermic
species in particular the external environment impinges directly
upon cellular and subcellular functions; i.e., directly upon cell
chemistry and cell metabolic machinery. Adaptive adjustments
in response to environmental change activated in one tissue therefoie
must be balanced with adjustments at other sites so as not too
seriously (i) to disrupt functions at other sites or (ii) to disrupt cooperative
metabolic interactions between tissues and organs in the
integrated physiology of the whole organism. Making problems
worse are simultaneous changes in more than one parameter of the
environment. Not only must organisms then cope with differential
effects of each parameter on specific metabolic processes or
upon specific tissues and organs; they must also successfully adjust
to interacting effects of the external environmental parameters
which may drive the same processes or pathways in the same or in
opposite directions
Contrasting mechanisms underlie shortâ and longerâterm soil respiration responses to experimental warming in a dryland ecosystem
Soil carbon losses to the atmosphere through soil respiration are expected to rise with ongoing temperature increases, but available evidence from mesic biomes suggests that such response disappears after a few years of experimental warming. However, there is lack of empirical basis for these temporal dynamics in soil respiration responses, and for the mechanisms underlying them, in drylands, which collectively form the largest biome on Earth and store 32% of the global soil organic carbon pool. We coupled data from a 10 year warming experiment in a biocrustâdominated dryland ecosystem with laboratory incubations to confront 0â2 years (shortâterm hereafter) versus 8â10 years (longerâterm hereafter) soil respiration responses to warming. Our results showed that increased soil respiration rates with shortâterm warming observed in areas with high biocrust cover returned to control levels in the longerâterm. Warmingâinduced increases in soil temperature were the main drivers of the shortâterm soil respiration responses, whereas longerâterm soil respiration responses to warming were primarily driven by thermal acclimation and warmingâinduced reductions in biocrust cover. Our results highlight the importance of evaluating shortâ and longerâterm soil respiration responses to warming as a mean to reduce the uncertainty in predicting the soil carbonâclimate feedback in drylands.This research was funded by the European Research Council (ERC Grant agreements 242658 [BIOCOM] and 647038 [BIODESERT]). M.D. is supported by an FPU fellowship from the Spanish Ministry of Education, Culture and Sports (FPU-15/00392). P.G.-P. is supported by a RamĂłn y Cajal grant from the Spanish Ministry of Science and Innovation (RYC2018-024766-I). S.A. acknowledges the Spanish MINECO for financial support via the DIGGING_DEEPER project through the 2015â2016 BiodivERsA3/FACCE-JPI joint call for research proposals. F.T.M. and S.A. acknowledge support from the Generalitat Valenciana (CIDEGENT/2018/041). C.C.-D. acknowledges support from the European Research Council (ERC Grant 647038 [BIODESERT])
Emerging Infectious Disease leads to Rapid Population Decline of Common British Birds
Emerging infectious diseases are increasingly cited as threats to wildlife, livestock and humans alike. They can threaten geographically isolated or critically endangered wildlife populations; however, relatively few studies have clearly demonstrated the extent to which emerging diseases can impact populations of common wildlife species. Here, we report the impact of an emerging protozoal disease on British populations of greenfinch Carduelis chloris and chaffinch Fringilla coelebs, two of the most common birds in Britain. Morphological and molecular analyses showed this to be due to Trichomonas gallinae. Trichomonosis emerged as a novel fatal disease of finches in Britain in 2005 and rapidly became epidemic within greenfinch, and to a lesser extent chaffinch, populations in 2006. By 2007, breeding populations of greenfinches and chaffinches in the geographic region of highest disease incidence had decreased by 35% and 21% respectively, representing mortality in excess of half a million birds. In contrast, declines were less pronounced or absent in these species in regions where the disease was found in intermediate or low incidence. Also, populations of dunnock Prunella modularis, which similarly feeds in gardens, but in which T. gallinae was rarely recorded, did not decline. This is the first trichomonosis epidemic reported in the scientific literature to negatively impact populations of free-ranging non-columbiform species, and such levels of mortality and decline due to an emerging infectious disease are unprecedented in British wild bird populations. This disease emergence event demonstrates the potential for a protozoan parasite to jump avian host taxonomic groups with dramatic effect over a short time period
Long-term effects of altered pH and temperature on the feeding energetics of the Antarctic sea urchin, Sterechinus neumayeri
Changes in labial capillary density on ascent to and descent from high altitude
Present knowledge of how the microcirculation is altered by prolonged exposure to hypoxia at high altitude is incomplete and modification of existing analytical techniques may improve our knowledge considerably. We set out to use a novel simplified method of measuring in vivo capillary density during an expedition to high altitude using a CytoCam incident dark field imaging video-microscope.
The simplified method of data capture involved recording one-second images of the mucosal surface of the inner lip to reveal data about microvasculature density in ten individuals. This was done on ascent to, and descent from, high altitude. Analysis was conducted offline by two independent investigators blinded to the participant identity, testing conditions and the imaging site. Additionally we monitored haemoglobin concentration and haematocrit data to see if we could support or refute mechanisms of altered density relating to vessel recruitment. Repeated sets of paired values were compared using Kruskall Wallis Analysis of Variance tests, whilst comparisons of values between sites was by related samples Wilcoxon Signed Rank Test. Correlation between different variables was performed using Spearmanâs rank correlation coefficient, and concordance between analysing investigators using intra-class correlation coefficient.
There was a significant increase in capillary density from London on ascent to high altitude; median capillaries per field of view area increased from 22.8 to 25.3 (p=0.021). There was a further increase in vessel density during the six weeks spent at altitude (25.3 to 32.5, p=0.017). Moreover, vessel density remained high on descent to Kathmandu (31.0 capillaries per field of view area), despite a significant decrease in haemoglobin concentration and haematocrit.
Using a simplified technique, we have demonstrated an increase in capillary density on early and sustained exposure to hypobaric hypoxia at thigh altitude, and that this remains elevated on descent to normoxia. The technique is simple, reliable and reproducible
Phase II study of the oxygen saturation curve left shifting agent BW12C in combination with the hypoxia activated drug mitomycin C in advanced colorectal cancer
BW12C (5-[2-formyl-3-hydroxypenoxyl] pentanoic acid) stabilizes oxyhaemoglobin, causing a reversible left-shift of the oxygen saturation curve (OSC) and tissue hypoxia. The activity of mitomycin C (MMC) is enhanced by hypoxia. In this phase II study, 17 patients with metastatic colorectal cancer resistant to 5-fluorouracil (5-FU) received BW12C and MMC. BW12C was given as a bolus loading dose of 45 mg kgâ1over 1 h, followed by a maintenance infusion of 4 mg kgâ1hâ1for 5 h. MMC 6 mg mâ2was administered over 15 min immediately after the BW12C bolus. The 15 evaluable patients had progressive disease after a median of 2 (range 1â4) cycles of chemotherapy. Haemoglobin electrophoresis 3 and 5 h after the BW12C bolus dose showed a fast moving band consistent with the BW12C-oxyhaemoglobin complex, accounting for approximately 50% of total haemoglobin. The predominant toxicities â nausea/vomiting and vein pain â were mild and did not exceed CTC grade 2. Liver31P magnetic resonance spectroscopy of patients with hepatic metastases showed no changes consistent with tissue hypoxia. The principle of combining a hypoxically activated drug with an agent that increases tissue hypoxia is clinically feasible, producing an effect equivalent to reducing tumour oxygen delivery by at least 50%. However, BW12C in combination with MMC for 5-FU-resistant colorectal cancer is not an effective regimen. This could be related to drug resistance rather than a failure to enhance cytotoxicity. © 2000 Cancer Research Campaig
AEROBIC AND ANAEROBIC SCALING IN FISH
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75506/1/j.1469-185X.1991.tb01134.x.pd
Global warming and Bergmannâs rule: do central European passerines adjust their body size to rising temperatures?
Recent climate change has caused diverse ecological responses in plants and animals. However, relatively little is known about homeothermic animalsâ ability to adapt to changing temperature regimes through changes in body size, in accordance with Bergmannâs rule. We used fluctuations in mean annual temperatures in south-west Germany since 1972 in order to look for direct links between temperature and two aspects of body size: body mass and flight feather length. Data from regionally born juveniles of 12 passerine bird species were analysed. Body mass and feather length varied significantly among years in eight and nine species, respectively. Typically the inter-annual changes in morphology were complexly non-linear, as was inter-annual variation in temperature. For six (body mass) and seven species (feather length), these inter-annual fluctuations were significantly correlated with temperature fluctuations. However, negative correlations consistent with Bergmannâs rule were only found for five species, either for body mass or feather length. In several of the species for which body mass and feather length was significantly associated with temperature, morphological responses were better predicted by temperature data that were smoothed across multiple years than by the actual mean breeding season temperatures of the year of birth. This was found in five species for body mass and three species for feather length. These results suggest that changes in body size may not merely be the result of phenotypic plasticity but may hint at genetically based microevolutionary adaptations
How useful are volunteers for visual biodiversity surveys? An evaluation of skill level and group size during a conservation expedition
The ability of volunteers to undertake different tasks and accurately collect data is critical for the success of many conservation projects. In this study, a simulated herpetofauna visual encounter survey was used to compare the detection and distance estimation accuracy of volunteers and more experienced observers. Experience had a positive effect on individual detection accuracy. However, lower detection performance of less experienced volunteers was not found in the group data, with larger groups being more successful overall, suggesting that working in groups facilitates detection accuracy of those with less experience. This study supports the idea that by optimizing survey protocols according to the available resources (time and volunteer numbers), the sampling efficiency of monitoring programs can be improved and that non-expert volunteers can provide valuable contributions to visual encounter-based biodiversity surveys. Recommendations are made for the improvement of survey methodology involving non-expert volunteers
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