Swim bladder function and buoyancy control in pink snapper (Pagrus auratus) and mulloway (Argyrosomus japonicus)     

John Stewart  Julian M. Hughes 《Fish physiology and biochemistry》2014,40(2):335-346

Physoclist fish are able to regulate their buoyancy by secreting gas into their hydrostatic organ, the swim bladder, as they descend through the water column and by resorbing gas from their swim bladder as they ascend. Physoclists are restricted in their vertical movements due to increases in swim bladder gas volume that occur as a result of a reduction in hydrostatic pressure, causing fish to become positively buoyant and risking swim bladder rupture. Buoyancy control, rates of swim bladder gas exchange and restrictions to vertical movements are little understood in marine teleosts. We used custom-built hyperbaric chambers and laboratory experiments to examine these aspects of physiology for two important fishing target species in southern Australia, pink snapper (Pagrus auratus) and mulloway (Argyrosomus japonicus). The swim bladders of pink snapper and mulloway averaged 4.2 and 4.9 % of their total body volumes, respectively. The density of pink snapper was not significantly different to the density of seawater (1.026 g/ml), whereas mulloway were significantly denser than seawater. Pink snapper secreted gas into their swim bladders at a rate of 0.027 ± 0.005 ml/kg/min (mean ± SE), almost 4 times faster than mulloway (0.007 ± 0.001 ml/kg/min). Rates of swim bladder gas resorption were 11 and 6 times faster than the rates of gas secretion for pink snapper and mulloway, respectively. Pink snapper resorbed swim bladder gas at a rate of 0.309 ± 0.069 ml/kg/min, 7 times faster than mulloway (0.044 ± 0.009 ml/kg/min). Rates of gas exchange were not affected by water pressure or water temperature over the ranges examined in either species. Pink snapper were able to acclimate to changes in hydrostatic pressure reasonably quickly when compared to other marine teleosts, taking approximately 27 h to refill their swim bladders from empty. Mulloway were able to acclimate at a much slower rate, taking approximately 99 h to refill their swim bladders. We estimated that the swim bladders of pink snapper and mulloway ruptured after decreases in ~2.5 and 2.75 times the hydrostatic pressure to which the fish were acclimated, respectively. Differences in buoyancy, gas exchange rates, limitations to vertical movements and acclimation times between the two species are discussed in terms of their differing behaviour and ecology.  相似文献   

Role of monocyte recruitment in hemangiosarcoma metastasis in dogs          下载免费PDF全文

D. P. Regan  A. Escaffi  J. Coy  J. Kurihara  S. W. Dow 《Veterinary and comparative oncology》2017,15(4):1309-1322

Canine hemangiosarcoma (HSA) is a highly malignant tumour associated with short survival times because of early and widespread metastasis. In humans and rodents, monocytes play key roles in promoting tumour metastasis through stimulating tumour cell extravasation, seeding, growth and angiogenesis. Therefore, we investigated the potential association between monocyte infiltration and tumour metastasis in HSA and other common canine tumours. Immunohistochemistry was used to quantify CD18⁺ monocytes within metastases. We found that HSA metastases had significantly greater numbers of CD18⁺ monocytes compared with metastases from other tumour types. HSA cells were the highest producers of the monocyte chemokine CCL2, and stimulated canine monocyte migration in a CCL2 dependent manner. These results are consistent with the hypothesis that overexpression of CCL2 and recruitment of large numbers of monocytes may explain in part the aggressive metastatic nature of canine HSA. Thus, therapies designed to block monocyte recruitment may be an effective adjuvant strategy for suppressing HSA metastasis in dogs.  相似文献   

Decreased Ratio of CD8+ T Cells to Regulatory T Cells Associated with Decreased Survival in Dogs with Osteosarcoma     

B.J. Biller  A. Guth  J.H. Burton  S.W. Dow 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2010,24(5):1118-1123

Background: Increased numbers of regulatory T cells (Treg) and decreased ratios of CD8+ T cells to Treg have been shown to correlate with decreased survival times (ST) in humans with certain malignancies. A possible connection between Treg and ST in dogs with cancer has not been investigated previously. Hypothesis: The purpose of this study was to compare numbers of Treg and T lymphocyte subsets in dogs with osteosarcoma (OSA) to those of healthy dogs and to determine whether pretreatment values were associated with disease‐free interval or with ST. We hypothesized that Treg numbers would be increased in dogs with cancer and that dogs with a high percentage of Treg would have a poorer prognosis. Animals: Twelve client‐owned dogs with appendicular OSA were entered into a prospective clinical trial. Twenty‐two healthy dogs were used as controls. Methods: The percentages and numbers of Treg and CD4+ and CD8+ T cells in blood, lymph nodes, and tumors were determined with flow cytometry and compared between dogs with OSA and control dogs. Results: Dogs with OSA had significantly fewer circulating CD8+ T cells and significantly more Treg compared with healthy dogs. The CD8/Treg ratio also was significantly lower in dogs with OSA compared with control dogs. In dogs with OSA, a decreased CD8/Treg ratio was associated with significantly shorter STs. Conclusions: These data support a role for Treg in the immune control of canine OSA and suggest that determination of the CD8/Treg ratio may be useful for assessing outcomes.  相似文献   

Hsp70 enhances presentation of FMDV antigen to bovine CD4+ T cells in vitro     

Kerry McLaughlin  Julian Seago  Lucy Robinson  Charles Kelly    Bryan Charleston 《Veterinary research》2010,41(3)

Foot-and-mouth disease virus (FMDV) is the causative agent of a highly contagious acute vesicular disease affecting cloven-hoofed animals, including cattle, sheep and pigs. The current vaccine induces a rapid humoral response, but the duration of the protective antibody response is variable, possibly associated with a variable specific CD4⁺ T cell response. We investigated the use of heat shock protein 70 (Hsp70) as a molecular chaperone to target viral antigen to the Major Histocompatibility Complex (MHC) class II pathway of antigen presenting cells and generate enhanced MHC II-restricted CD4⁺ T cell responses in cattle. Monocytes and CD4⁺ T cells from FMDV vaccinated cattle were stimulated in vitro with complexes of Hsp70 and FMDV peptide, or peptide alone. Hsp70 was found to consistently improve the presentation of a 25-mer FMDV peptide to CD4⁺ T cells, as measured by T cell proliferation. Complex formation was required for the enhanced effects and Hsp70 alone did not stimulate proliferation. This study provides further evidence that Hsp70:peptide complexes can enhance antigen-specific CD4⁺ T cell responses in vitro for an important pathogen of livestock.  相似文献   

Tumor necrosis factor-α and acute-phase proteins in early pregnant ewes after challenge with peptidoglycan-polysaccharide     

T.L. Dow  G. Rogers-Nieman  I. Holásková  T.H. Elsasser  R.A. Dailey 《Domestic animal endocrinology》2010

Bacterial infection shortly after mating interferes with establishment of pregnancy. Injection of peptidoglycan-polysaccharide (PG-PS), a component of gram-positive bacteria, into sheep on day 5 after mating reduces pregnancy rate. Experiments were designed to evaluate the acute-phase response (APR) in ewes to injection of PG-PS on day 5 after mating (day 0). Catheters were inserted into the jugular and posterior vena cava on day 4. On day 5, ewes were challenged with saline or 30 μg/kg body weight (BW) PG-PS (Exp 1) or 60 μg/kg BW PG-PS (Exp 2). Blood samples were collected every 15 min for 6 h (Exp 1) and every 15 min for 2 h, hourly for 12 h, and at 24, 36, and 48 h (Exp 2). Body temperature and clinical signs of infection were monitored in Exp 2. Plasma was assayed for concentrations of a pro-inflammatory cytokine, tumor necrosis factor-α (TNF-α); 2 APR proteins, serum amyloid A (SAA) and haptoglobin (Hp); and progesterone (P₄). Ewes injected with 60 μg/kg BW PG-PS exhibited fever, vaginal discharge, loss of appetite, and lethargy. After challenge with either 30 μg/kg or 60 μg/kg BW PG-PS, TNF-α increased in the posterior vena cava. Concentrations of SAA and Hp in the jugular increased after challenge with 60 μg/kg BW PG-PS. Only half (5/10) of the ewes treated with 60 μg/kg BW PG-PS had ultrasonically visible embryos, and none of them had functional corpora lutea (CL) (<1 ng/mL of P₄) on day 21. On the other hand, 8/9 (88.9%) control ewes had visible embryos and all had functional CL on day 21. Using logistic regression, pregnancy on day 21 was predicted to depend on concentrations of TNF-α and Hp on day 5 and concentration of P₄ on day 14. In summary, injection of PG-PS on day 5 after mating resulted in fever; increased concentrations of TNF-α, Hp, and SAA on the day of and the day after the PG-PS challenge; and decreased concentrations of P₄ on days 14 and 21. These factors were related to failure to establish pregnancy.  相似文献   

Resin pocket occurrence in Norway spruce depending on tree and climate variables     

Thomas Seifert  Julian Breibeck  Stefan Seifert  Peter Biber 《Forest Ecology and Management》2010

Resin or pitch pockets cause a significant reduction in timber quality of Norway spruce (Picea abies (L.) Karst). Their occurrence is very variable within the stem and between trees and stands. Researchers have suggested several causes of resin pocket formation with a majority arguing in favour of storms as the main causing factor.  相似文献   

Exploring the relevance of a landscape ecological paradigm for sustainable landscapes and livelihoods: A case-application from the Northern Territory Australia     

Diane M. Pearson  Julian T. Gorman 《Landscape Ecology》2010,25(8):1169-1183

Global change is exacerbating the need for more effective mechanisms and approaches for working towards economic, social/cultural and environmental sustainability. It is now well recognised that science for sustainability will require integrated problem-focussed research that is by nature trans-disciplinary. Resolutions to both global and regional scale issues must involve participation of a diverse number of stakeholders. One region that would benefit greatly from such an integrated approach is the Northern Territory of Australia. This area is home to some of the most pristine savanna landscapes in the world and it is also occupied by one of the oldest living human cultures which are still in existence today. However, in recent years there has been increasing pressure to develop this region. The Northern Territory is also facing problems associated with having a growing Aboriginal population with deepening health and social problems. So as well as needing to facilitate adaptation in response to global change and development for economic prosperity of the region, there is an obligation to alter management practices to reduce social disadvantage. In light of this, it will be important that future landscapes are multifunctional and designed to ensure the preservation of biological and cultural diversity, as well as having provision for the livelihoods of the people that live within them. This article recommends the adoption of a landscape ecological approach for strategic development and sustainable planning, which captures and incorporates the values and identities of the different stakeholders, as well as engaging them in a continuous, adaptive process of planning and management, and in doing so discusses the importance of human ecological holism as part of the conceptual framework for landscape ecology.  相似文献   

博落回中季铵类苯并啡啶类生物碱的提取及其硫酸氢盐的抗菌活性和急性毒性     

王斌  程辟  陈巨莲  曾建国 《农药学学报》2013,15(3):299-304

采用酸提碱沉的方法,从博落回中提取并制备了苯并啡啶类生物碱(QBAs)——血根碱(sanguinarine)和白屈菜红碱(chelerythrine)的硫酸氢盐;采用高效液相色谱法测定了2种生物碱的含量;初步测定了其硫酸氢盐对几种常见病原菌的抗菌活性,并对其急性毒性进行了研究。结果表明:所制备的QBAs硫酸氢盐中血根碱和白屈菜红碱的质量分数均在60%以上。生物测定结果表明,该生物碱的硫酸氢盐对葡萄叶斑病菌Cercospora viticola、葡萄黑豆病菌Elsinoe ampelina、葡萄炭疽病菌Colletotrichum gloeosporioides、葡萄褐斑病菌Cercospora viticola、稻瘟病菌Pvricularia oryzae、小麦赤霉病菌Gibberella zeae和辣椒疫霉Phytophythora capsici均具有较强的抑制作用,EC50值在3.35～10.08 μg/mL之间。其急性毒性属低毒,对皮肤有弱致敏性,但对眼睛有重度刺激性。博落回中QBAs硫酸氢盐制备方法稳定,具有较强的抗菌活性,可考虑开发成低毒、环境友好型植物源杀菌剂。  相似文献   

Rushmore,a new obloxg baking type potato     

Julian C. Miller 《American Journal of Potato Research》1957,34(3):68-69

  相似文献   

Helpful hints in the cutting and planting of seed potatoes     

Albert G. Fradkin  George F. Dow  M. W. Parker 《American Journal of Potato Research》1963,40(3):103-107

  相似文献