Flow alteration and thermal pollution depress modelled growth rates of an iconic riverine fish,the Murray cod Maccullochella peelii

The serial discontinuity concept (SDC) proposes that hypolimnetic‐releasing impoundments cause major disruptions to the naturally occurring physical, chemical and biological gradients of rivers but that this impact diminishes with distance downstream. Such a gradient in discharge, flow velocity and temperature regime occurs below a large hypolimnetic‐releasing impoundment, the Hume Dam, on the River Murray in south‐eastern Australia. To examine the effects of this disturbance gradient on a warm‐water large‐bodied freshwater fish, the Murray cod (Maccullochella peelii), a bioenergetics model was developed and calibrated to explore energy expended under differing water velocities and temperature regimes. Model simulations predicted negative growth of juveniles directly downstream of the impoundment, due largely to the energetic costs associated with active and, to a lesser extent, standard metabolism outweighing the achievable energetic gains through food consumption. As flow velocity and temperature regimes became more favourable downstream, so did the simulated growth of the species. It was not until +239 km downstream of the impoundment that the model predicted that flow velocity and temperature regimes were suitable for greater weight gains. The modelled growth responses of juvenile Murray cod are consistent with the predictions of the SDC, emphasising that changes in the bioenergetics of individuals are likely to be reflected in reduced growth rates under the changed flow velocity and temperature regimes imposed by disturbance gradients. This research represents a valuable step in the biological understanding of Murray cod within variable riverine environments and emphasises the urgency required to mitigate impacts associated with hypolimnetic impoundments.     

Relationships between soil and foliar nutrients in young densely planted mini-plots of Pinus radiata and Cupressus lusitanica

The long-term nature of forest crop rotations makes it difficult to determine impacts of forestry on soil nutrients that might be depleted by forest growth. We used small scale, highly stocked plots to compress the length of the rotation and rapidly induce nutrient depletion. In the study, two species (Pinus radiata D. Don and Cupressus lusitanica Miller) are compared under two disturbance regimes (soil undisturbed and compacted), and two fertiliser treatments (nil and plus fertiliser), applied in factorial combination at 33 sites, covering the range of climatic and edaphic variation found in plantation forests across New Zealand. To assess our ability to rapidly highlight important soil properties, foliar nutrient concentrations were determined 20 months after planting. It was hypothesised that the densely planted plots, even at a young age, would create sufficient pressure on nutrient resources to allow development of relationships between properties used as indicies of soil nutrient availability and foliar nutrient concentrations. For both species significant relationships between foliar nutrients and 0–10 cm layer soil properties from unfertilised plots were evident for N (total and mineralisable N) and P (total, acid extractable, organic, Bray-2 and Olsen P). With the exception of Ca in C. lusitanica, foliar K, Ca and Mg were correlated with their respective soil exchangeable cation measures. The results thus confirm the utility of the experimental approach and the relevance of the measured soil properties for forest productivity.

In unfertilised plots foliar N and P concentrations in P. radiata exceeded those in C. lusitanica, the differences being eliminated by fertiliser application. Foliar N/P ratios in P. radiata also exceeded those in C. lusitanica. In contrast to N and P, foliar K, Ca and Mg concentrations were all higher in C. lusitanica, the difference being particularly marked for Ca and Mg. P. radiata contained substantially higher concentrations of the metals Zn, Mn and Al than C. lusitanica, whereas the latter contained higher B concentrations. Possible reasons for differences between species in foliar nutrient concentrations are discussed.     

Some physicochemical factors influencing foliar uptake enhancement of glyphosatemono(isopropylammonium) by polyoxyethylene surfactants

Structure-concentration–foliar uptake enhancement relationships between commercial polyoxyethylene primary aliphatic alcohol (A), nonylphenol (NP), primary aliphatic amine (AM) surfactants and the herbicide glyphosatemono(isopropylammonium) were studied in experiments with wheat (Triticum aestivum L.) and field bean (Vicia faba L.) plants growing under controlled-environment conditions. Candidate surfactants had mean molar ethylene oxide (EO) contents ranging from 5 to 20 and were added at concentrations varying from 0·2 to 10 g litre^?-1 to [¹⁴C]glyphosate formulations in acetone–water. Rates and total amounts of herbicide uptake from c. 0·2–μl droplet applications of formulations to leaves were influenced by surfactant EO content, surfactant hydrophobe composition, surfactant concentration, glyphosate concentration and plant species, in a complex manner. Surfactant effects were most pronounced at 0·5 g acid equivalent (a.e.) glyphosate litre^?-1 where, for both target species, surfactants of high EO content (15–20) were most effective at enhancing herbicide uptake: surfactants of lower EO content (5–10) frequently reduced, or failed to improve, glyphosate absorption. Whereas, at optimal EO content, AM surfactants caused greatest uptake enhancement on wheat, A surfactants gave the best overall performance on field bean; NP surfactants were generally the least efficient class of adjuvants on both species. Threshold concentrations of surfactants needed to increase glyphosate uptake were much higher in field bean than wheat (c. 2 g litre^?-1 and < 1 g litre^?-1, respectively); less herbicide was taken up by both species at high AM surfactant concentrations. At 5 and 10 g a.e. glyphosate litre^?-1, there were substantial increases in herbicide absorption and surfactant addition could cause effects on uptake that were different from those observed at lower herbicide doses. In particular, the influence of EO content on glyphosate uptake was now much less marked in both species, especially with AM surfactants. The fundamental importance of glyphosate concentration for its uptake was further emphasised by experiments using formulations with constant a.i./surfactant weight ratios. Any increased foliar penetration resulting from inclusion of surfactants in 0·5 g litre^?-1 [¹⁴C]glyphosate formulations gave concomitant increases in the amounts of radiolabel that were translocated away from the site of application. At these low herbicide doses, translocation of absorbed [¹⁴C]glyphosate in wheat was c. twice that in field bean; surfactant addition to the formulation did not increase the proportion transported in wheat but substantially enhanced it in field bean.     

Surfactant-enhanced foliar uptake of some organic compounds: Interactions with two model polyoxyethylene aliphatic alcohols

Interactions occurring during the surfactant-enhanced foliar uptake of seven model organic compounds were examined using two homogeneous surfactants, hexaethylene glycol monotridecyl ether (C13E6) and hexadecaethylene glycol monododecyl ether (C12E16). Surfactant–compound and compound–surfactant interactions were detected by measurement of their relative uptake rates following application of c. 0·2 μl droplets of the corresponding radiolabelled formulations. The magnitude of surfactant–compound interaction was found to vary according to the physicochemical properties of both the compound and the surfactant, and was influenced by surfactant concentration and target plant species. Interactive and non-interactive mechanisms, both leading to substantial enhancement of compound uptake, could be identified, but their precise nature could not be elucidated. Although penetration of C13E6 into the site of application appeared to be essential in order to activate the uptake of a compound, substantial absorption of C12E16 was not always required to produce the same effect. The results are discussed in the light of possible sites and modes of action for activator polyoxyethylene surfactant adjuvants.     

Abomasal secretion in sheep receiving adult Ostertagia circumcincta that are prevented from contact with the mucosa

AIMS: Both adult and larval Ostertagia circumcincta infections raise abomasal pH and serum gastrin and pepsinogen concentrations, either because of physical effects of the worms or from their chemical secretions. The study was designed to examine whether adult worms require contact with the gastric mucosa to effect changes in gastric secretion. METHODS: Abomasal pH and serum gastrin and pepsinogen concentrations were measured in four groups of sheep: Group A (n = 4): abomasal contents containing about 18,000 adult O. circumcincta were obtained from donor sheep, concentrated and infused into 5 microm mesh porous bags attached to surgically implanted abomasal cannulae. A second worm transplantation was carried out 1 week later to assess worm survival after 16 hours. Group B (n = 4): about 9000 adult worms, recovered after migration out of abomasal contents set in agar, were placed in small 5 microm mesh bags which were inserted through indwelling abomasal cannulae and left for 3 days. Group C (n = 2): about 3000 adult worms from the population recovered from agar were infused through abomasal cannulae which allowed. free movement in the abomasum. Group D (n = 3) was left uninfected. RESULTS: Worms transplanted directly into the abomasum (Group C) caused rapid and marked effects on abomasal secretion. Adult O. circumcincta died within 16 hours of transfer into the abomasum when they were restrained within porous bags. Nevertheless, in sheep receiving 18,000 worms, abomasal pH increased soon after new feed was presented on Days 1, 2 and 4 after worm transfer; serum gastrin was elevated in three sheep from 113 hours and serum pepsinogen increased in one animal. Sheep receiving 9000 worms showed similar trends but the results were equivocal. CONCLUSIONS: Adult O. circumcincta prevented from physical contact with the gastric mucosa by restraint in porous bags are able to raise abomasal pH. This study implicates parasite excretory-secretory products in mediating changes in gastric secretion caused by adult abomasal worms.     

A sequential study of the pathology associated with the infection of sheep with adult and larval Ostertagia circumcincta

Disturbances in the physiology of the abomasa of sheep infected with either adult Ostertagia circumcincta given via abomasal cannulae, or larvae (L3) given intraruminally were matched by pathological changes in tissues collected by repeated mucosal biopsy. Within 2-3 days of the transplant of adult worms, abomasal pH had increased markedly in five out of six animals, and there also had been rapid increases in serum gastrin and pepsinogen concentrations in all animals. Reductions in parietal cell number were recorded as early as 1 day after the transplant of adults and were associated with the rapid accumulation of many neutrophils and eosinophils. Mucosal hyperplasia, with increased numbers of cells closer in appearance to mucous/mucous neck cells, was a relatively late development, being most pronounced in the latter part of the infection. In sheep given larvae, changes in secretory physiology were again matched by a concurrent fall in parietal cell number and by the accumulation of inflammatory cells. Changes became maximal when most worms could be expected to be present as adults, confirming the role of adults in the natural disease. Some abnormalities were detected in biopsies collected from animals maintained free of parasites and, although milder in degree, there were similarities to those observed in parasitised tissues, there being fewer parietal cells, a modest degree of mucous cell hyperplasia and inflammatory infiltrates of predominantly neutrophils. These changes were the likely result of trauma to the tissues in the immediate vicinity of the cannula, due either to the presence of the cannula itself or to the frequent collection of biopsy material from areas close to it.     

Implications of simian retroviruses for captive primate population management and the occupational safety of primate handlers.

Nonhuman primates can be naturally infected with a plethora of viruses with zoonotic potential, including retroviruses. These simian viruses present risks to both captive nonhuman primate populations and persons exposed to nonhuman primates. Simian retroviruses, including simian immunodeficiency virus, simian type D retrovirus, simian T-lymphotropic virus, and gibbon ape leukemia virus, have been shown to cause clinical disease in nonhuman primates. In contrast, simian foamy virus, a retrovirus that is highly prevalent in most nonhuman primates, has not been associated with clinical disease in naturally infected primates. Although it has been shown that human retrovirus infections with human T-lymphotropic virus and human immunodeficiency virus originated through multiple independent introductions of simian retroviruses into human populations that then spread globally, little is known about the frequency of such zoonotic events. In this article, exogenous simian retroviruses are reviewed as a concern for zoo and wildlife veterinarians, primate handlers, other persons in direct contact with nonhuman primates, and other nonhuman primates in a collection. The health implications for individual animals as well as managed populations in zoos and research institutions are discussed, the cross-species transmission and zoonotic disease potential of simian retroviruses are described, and suggestions for working safely with nonhuman primates are provided.     

Redox regulation of germline and vulval development in Caenorhabditis elegans

In vitro studies have indicated that reactive oxygen species (ROS) and the oxidation of signaling molecules are important mediators of signal transduction. We have identified two pathways by which the altered redox chemistry of the clk-1 mutants of Caenorhabditis elegans acts in vivo on germline development. One pathway depends on the oxidation of an analog of vertebrate low density lipoprotein (LDL) and acts on the germline through the Ack-related tyrosine kinase (ARK-1) kinase and inositol trisphosphate (IP3) signaling. The other pathway is the oncogenic ras signaling pathway, whose action on germline as well as vulval development appears to be modulated by cytoplasmic ROS.     

Serum chemistry comparisons between captive and free-ranging giraffes (Giraffa camelopardalis)

Serum chemistry analyses were compared between captive and free-ranging giraffes (Giraffa camelopardalis) in an attempt to better understand some of the medical issues seen with captive giraffes. Illnesses, including peracute mortality, energy malnutrition, pancreatic disease, urolithiasis, hoof disease, and severe intestinal parasitism, may be related to zoo nutrition and management issues. Serum samples were collected from 20 captive giraffes at 10 United States institutions. Thirteen of the captive animal samples were collected from animals trained for blood collection; seven were banked samples obtained from a previous serum collection. These samples were compared with serum samples collected from 24 free-ranging giraffes in South Africa. Differences between captive and free-ranging giraffes, males and females, and adults and subadults were analyzed by using a 2 x 2 x 2 factorial and Fisher's least significant difference for mean separation; when necessary variables were ranked and analyzed via analysis of variance. Potassium and bilirubin concentrations and alanine aminotransferase (ALT) activities were different between captive and free-ranging giraffes, but all fell within normal bovid reference ranges. The average glucose concentration was significantly elevated in free-ranging giraffes (161 mg/dl) compared with captive giraffes (113 mg/dl). All giraffes in this study had glucose concentrations higher than bovine (42-75 mg/ dl) and caprine (48-76 mg/dl) reference ranges. Differences were also seen in lipase, chloride, and magnesium though these findings are likely not clinically significant. There were no differences detected between sexes. Adults had higher concentrations of potassium, total protein, globulins, and chloride and higher gamma glutamyltransferase activities, whereas subadults had higher concentrations of phosphorus. Within the captive group, nonimmobilized animals had higher concentrations of total protein and globulins. Captive giraffe diets need further investigation to determine if the differences seen in this study, especially glucose and bilirubin concentrations and ALT activities, may result in some health problems often seen in captive giraffes.     

Interleukins: Biological Properties and Therapeutic Potential

Interleukins are biologically active glycoproteins derived primarily from activated lymphocytes and macrophages. Tremendous insight into the biochemical and biological properties of interleukins has been gained with advances in recombinant DNA technology, protein purification, and cell-culture techniques. The biological properties of interleukins include induction of T-lymphocyte activation and proliferation, augmentation of neutrophil, macrophage, and T-lymphocyte cytotoxicity, and promotion of B lymphocyte and multilineage bone marrow stem-cell precursor growth and differentiation. Interleukins may play a role in the pathogenesis of several important diseases. Interleukin therapy is likely to play an important role in the treatment of cancer, infectious diseases, and immunodeficiency syndromes.