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Clear Response (clear + response)
Selected AbstractsAre distributions of fishes in tropical estuaries influenced by turbidity over small spatial scales?JOURNAL OF FISH BIOLOGY, Issue 3 2007R. Johnston This study found no evidence that turbidity influenced the distribution of fishes in four tropical estuaries in north-eastern Queensland. When both more turbid and less turbid environments were immediately available to Ambassis vachelli and Leiognathus equulus there was no difference in abundance between the more and less turbid environments and no correlated change in abundance as the difference in turbidity increased. A similar outcome was evident for an additional six species of fish. Furthermore, the distribution of fishes was not correlated with the distribution of an important prey species, juvenile banana prawns Penaeus merguiensis, which exhibited a clear response to differences in turbidity level with higher abundance in the more turbid samples, however, the magnitude of the difference did not alter with changes in the magnitude of the differences in turbidity. [source] A multiproxy record of Holocene environmental changes in the central Kola Peninsula, northwest RussiaJOURNAL OF QUATERNARY SCIENCE, Issue 4 2002Nadia Solovieva Abstract A sediment core from Chuna Lake (Kola Peninsula, northwest Russia) was studied for pollen, diatoms and sediment chemistry in order to infer post-glacial environmental changes and to investigate responses of the lake ecosystem to these changes. The past pH and dissolved organic carbon (DOC) of the lake were inferred using diatom-based transfer functions. Between 9000 and 4200 cal. yr BP, slow natural acidification and major changes in the diatom flora occurred in Chuna Lake. These correlated with changes in regional pollen, the arrival of trees in the catchment, changes in erosion, sediment organic content and DOC. During the past 4200 yr diatom-based proxies showed no clear response to changes in vegetation and erosion, as autochthonous ecological processes became more important than external climate influences during the late Holocene. The pollen stratigraphy reflects the major climate patterns of the central Kola Peninsula during the Holocene, i.e. a climate optimum between 9000 and 5400/5000 cal. yr BP when climate was warm and dry, and gradual climate cooling and an increase in moisture during the past 5400/5000 yr. This agrees with the occurrence of the north,south humidity gradient in Fennoscandia during the Holocene. Copyright © 2002 John Wiley & Sons, Ltd. [source] Response of workers of Atta sexdens rubropilosa (Hymenoptera: Formicidae) to mandibular gland compounds of virgin males and femalesPHYSIOLOGICAL ENTOMOLOGY, Issue 3 2007J. MAURÍCIO S. BENTO Abstract The secretion from the mandibular glands of males of the leaf-cutting ant Atta sexdens rubropilosa is responsible for the reaction of workers outside the nest at the time of sexual swarming. Workers respond with excitability and aggression when presented with the natural mixture of 4-methyl-3-heptanol and 4-methyl-3-heptanone, which is contained in the secretion of the male mandibular glands. Workers respond quickly to fractional amounts of one male equivalent. 4-Methyl-3-heptanone, from the virgin female mandibular glands causes much less response in workers, whereas an equimolar mixture of male and female pheromones gives a still less clear response. The male pheromone plays the most important part in the communication of workers outside the nest at this time. [source] Effects of transplants and extracts of thoracic nerve cord,ganglia on gonad maturation of penaeoid shrimpAQUACULTURE RESEARCH, Issue 2 2010Jorge Alfaro Abstract It has been established recently that interspecific and intraspecific thoracic ganglia transplants from Penaeidae are gradually absorbed by the host without activating an encapsulation mechanism. Therefore, this research was designed to evaluate the thoracic ganglia extracts and implants from maturing Trachypenaeus byrdi (Burkenroad), Xiphopenaeus riveti (Bouvier) and Penaeus (Litopenaeus) occidentalis (Streets) females as potential inducers of sexual maturation in Penaeus (Litopenaeus) stylirostris (Stimpson), Penaeus (Litopenaeus) vannamei (Boone) and T. byrdi, from the Gulf of Nicoya, Costa Rica. Our findings suggest that interspecific and intraspecific thoracic ganglia extracts or implants from maturing penaeoid females are not capable of inducing a clear response in sexual maturation in males or females. Tissues were tested at increasing doses from 137, 386, 525 and 1500 ,g g,1 body weight, without any positive response. It is proposed that a hypothetical hormone, vitellogenesis-stimulating hormone, from the thoracic ganglia, is under the strong negative control of eyestalks, by the gonad-inhibiting hormone in the subgenus Litopenaeus. Therefore, the use of thoracic ganglia extracts or implants would be ineffective when compared with injecting serotonin alone, as the present results seem to support. [source] Different response to rituximab in tumor necrosis factor blocker,naive patients with active ankylosing spondylitis and in patients in whom tumor necrosis factor blockers have failed: A twenty-four,week clinical trial,ARTHRITIS & RHEUMATISM, Issue 5 2010I.-H. Song Objective Histologic studies have shown B cell clusters in the subchondral bone marrow of the spine of patients with ankylosing spondylitis (AS). An immunotherapy targeting B cells in AS is therefore of interest. We undertook this study to examine the efficacy and safety of rituximab in patients with AS refractory to nonsteroidal antiinflammatory drugs in whom previous treatment with tumor necrosis factor , (TNF,) blockers either had not been tried or had failed. Methods In this phase II clinical trial, 1,000 mg rituximab was administered intravenously at baseline and at week 2 in 20 patients with active AS. Ten of these patients had never received TNF blockers, and treatment with TNF blockers had failed in the other 10 patients. The primary end point was a 20% improvement in disease activity at week 24 according to the criteria of the Assessment of SpondyloArthritis international Society (an ASAS20 response). Results Seventy-five percent of the patients were male, 90% were HLA,B27 positive, their mean age was 39.7 years, and their mean disease duration was 16.8 years. Patients had active disease, defined as a Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score ,4. While there was no clear response at week 24 in the group in whom TNF blockers had failed (30% had achieved an ASAS20 response, 10% had achieved an ASAS40 response, none had achieved partial remission according to the ASAS criteria, and none had achieved 50% improvement on the BASDAI [a BASDAI50 response] beyond an expected placebo response), we observed a good improvement in the TNF blocker,naive group at week 24 (50% had achieved an ASAS20 response, 40% had achieved an ASAS40 response, 30% had achieved partial remission according to the ASAS criteria, and 50% had achieved a BASDAI50 response). Conclusion Although rituximab does not seem to be effective in patients with AS that does not respond to TNF blockers, it had significant efficacy in TNF blocker,naive patients. Therefore, further controlled trials with B cell,directed therapies should be performed in TNF blocker,naive AS patients in the future. [source] Aspen succession and nitrogen loading: a case for epiphytic lichens as bioindicators in the Rocky Mountains, USAJOURNAL OF VEGETATION SCIENCE, Issue 3 2009Paul C. Rogers Abstract Question: Can lichen communities be used to assess short- and long-term factors affecting seral quaking aspen (Populus tremuloides) communities at the landscape scale? Location: Bear River Range, within the Rocky Mountains, in northern Utah and southern Idaho, USA. Method: Forty-seven randomly selected mid-elevation aspen stands were sampled for lichens and stand conditions. Plots were characterized according to tree species cover, basal area, stand age, bole scarring, tree damage, and presence of lichen species. We also recorded ammonia emissions with passive sensors at 25 urban and agricultural sites throughout an adjacent populated valley upwind of the forest stands. Nonmetric multidimensional scaling (NMS) ordination was used to evaluate an array of 20 variables suspected to influence lichen communities. Results: In NMS, forest succession explained most variance in lichen composition and abundance, although atmospheric nitrogen from local agricultural and urban sources also significantly influenced the lichen communities. Abundance of nitrophilous lichen species decreased with distance from peak ammonia sources and the urban center in all aspen succession classes. One lichen, Phaeophyscia nigricans, was found to be an effective bioindicator of nitrogen loading. Conclusions: Lichen communities in this landscape assessment of aspen forests showed clear responses to long-term (stand succession) and short-term (nitrogen deposition) influences. At the same time, several environmental factors (e.g. tree damage and scarring, distance to valley, topography, and stand age) had little influence on these same lichen communities. We recommend further use of epiphytic lichens as bioindicators of dynamic forest conditions. [source] | ||||||||||