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Rehabilitation efforts for live stranded marine mammals are guided by diagnostic measures of blood chemistry and hematology parameters obtained from each individual undergoing treatment. Despite the widespread use of blood parameters, reference values are not available in the literature from healthy rough-toothed dolphins ( Steno bredanensis) with which to infer the health status of an animal. We examined serum or plasma chemistry and hematology data from 17 rough-toothed dolphins either housed at Dolphin Quest French Polynesia or during their rehabilitation at the Dolphin and Whale Hospital in Sarasota, Florida, US between 1994 and 2005. Blood parameters were compared among healthy animals, rehabilitation animals that were eventually released, and rehabilitation animals that died. This study indicated significant differences in many blood parameters for the poorly known rough-toothed dolphin that are likely to vary between healthy and sick animals. These included aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, bicarbonate, and globulins, which were greater in sick dolphins, and alkaline phosphatase and total protein which were greater in healthy individuals. Total white blood cell counts were lower in healthy animals as were the absolute numbers of neutrophils, monocytes, and eosinophils. Analysis of first blood sample levels for glucose, sodium, and erythrocyte sedimentation rate may have value for triage and prognostic evaluation.

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Many local livestock breeds in developing countries are being replaced by exotic breeds, leading to a loss of genetic resources. In southern Mali, for the past two decades, a trend towards increasing crossbreeding between the trypanotolerant N'Dama cattle and the trypano-susceptible Fulani Zebu cattle has been taking place. A survey with 160 farmers owning a cattle herd was carried out in southern Mali to investigate their production objectives, as well as trait and breed preferences and correlated socio-economic determinants in order to understand farmers' breeding decisions and to identify comparative advantages of three breed groups (N'Dama, Fulani Zebu and crossbreds) raised in the study area. Data were analyzed using an exploded logit model. The reasons for raising cattle, as well as trait and breed preferences reflected the multiple objectives of the farmers. Draught power and savings were the most important production objectives. Productive traits were ranked highest; farmers reported large body size as the most preferred trait, followed by fertility, draught ability and milk yield. Crossbreds were the favored breed group. Breed preferences were mainly explained by 'resistance to disease' for N'Dama cattle and 'high market price' for Fulani Zebu and crossbred cattle. Production objectives, trait and breed preferences were mainly influenced by farmer group (local farmers and settled transhumants). Local farmers put comparatively more emphasis on livestock functions linked to crop production such as draught power. They had a higher preference for traction ability as a selection trait and preferred N'Dama over Fulani Zebu cattle. Settled transhumants emphasized milk yield as a selection trait and preferred Fulani Zebu over N'Dama. The results indicate that the trend towards more crossbreeding will continue putting the N'Dama breed under high risk of genetic dilution in southern Mali. The N'Dama cattle remain a valuable breed due to their adaptive traits such as disease and drought tolerance and their good traction ability, fulfilling the diverse objectives of local farmers. Crossbreeding was found to be a promising breeding strategy, which might contribute to the maintenance of the local breed, provided that breeding schemes are thoroughly planned and organized.

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OBJECTIVES: It is currently unknown whether chronic wasting disease (CWD), a transmissible spongiform encephalopathy of cervids, is transmissible to humans. Reported on here are the behavioural risk factors and health conditions associated with a six-year follow-up of a known point-source exposure to a CWD infected deer in an Upstate New York community. STUDY DESIGN: Longitudinal. METHODS: The Oneida County Chronic Wasting Disease Surveillance Project was launched in 2005 in response to a point-source exposure to a CWD infected deer at a March 2005 Sportsmen's feast in Upstate New York. Eighty-one exposed individuals participated in the 2005 baseline data collection, and were sent follow-up questionnaires following each deer hunting season between 2005 and 2011. RESULTS: Over a six year period, participants reported a reduction in overall venison consumption. Participants reported no significant changes in health conditions, although several conditions (vision loss, heart disease, type 2 diabetes, weight changes, hypertension, and arthritis), were significantly associated with age. CONCLUSIONS: To this day, this incident remains the only known large-scale point-source exposure to a CWD infected deer. Prion diseases can incubate for multiple decades before the manifestation of clinical symptoms; thus, continued surveillance of this exposed study population represents a unique opportunity to assess the risk of CWD transmission to humans. This project is uniquely situated to provide the first epidemiological evidence of CWD transmission to humans, should it occur.

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BACKGROUND: Esophageal adenocarcinomas (EACs) arise due to gastroesophageal reflux, with Barrett's esophagus (BE) regarded as precancerous lesion. Glucocorticoid-induced TNFR family-related Receptor (GITR)-mediated inflammation of tumor infiltrating leucocytes (TILs) in the tumor microenvironment might play a role during the multistep carcinogenetic process as either tumor promoting factor according to an inflammatory microenvironment or as a feature of anti-tumor activity. METHODS: Immunohistochemical analysis of GITR expression was analyzed in esophageal cancer (n=70: 41 EAC with BE, 19 EAC without BE, and n=10 esophageal squamous-cell carcinomas, ESCC), the adenocarcinoma cell line OE-33, and peripheral blood leucocytes (PBLs) of EAC patients, furthermore in biopsies of BE without intraepithelial neoplasia (IN) (n=18). Results were correlated with clinicopathological parameters and five-year survival rates. Immunohistochemical GITR expression results were confirmed on mRNA level (RT-PCR). RESULTS: Quantification showed a significant increase of 25% GITR positive TILs in EAC with BE (p< 0.05) compared to 13% in adjacent BE, 24% in EAC without BE, 14% in ESCC, and 1% in BE without IN. High GITR levels were not significantly associated with clinicopathologic features which may predict worse clinical outcome and had no impact on survival (p= 0.7878). Increased GITR expression of peripheral blood leucocytes (PBLs) in EAC patients was shown on protein level (32%) and confirmed by RT-PCR (3.7-fold difference compared to normal tissue). CONCLUSIONS: This study provides for the first time evidence that GITR expression of TILs is associated in the pathogenesis of Barrett's esophagus. Our findings suggest that GITR-expression of TILs is associated with cancer progression. Its role as either tumor promoting factor %according to an in the inflammatory microenvironment or as a feature of anti-tumor activity and promising target for molecular therapies needs to be substantiated in further investigations.

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The ventricular pressure-volume (PV) relationship has been used extensively to study the mechanics and energetics in multi-chambered hearts of closed circulatory system vertebrates. In the current study we applied the use of PV loops in the assessment of cardiac mechanics and energetics in the single ventricle of a decapod crustacean possessing an open circulatory system. Anatomical differences between multi-and single-chambered hearts include multiple ostia entering and valved multiple arterial systems exiting the ventricle, and the neurogenic origin of the heartbeat in decapod crustaceans. However, the microscopic architecture and excitation-contraction coupling events are similar in both systems. Ventricular pressure and area were obtained independently and integrated into pressure-area loops. Area was then converted to volume to generate PV loops. Based on the PV loops generated in this study, the ventricle of Palaemonetes pugio processes the same primary phases of the cardiac cycle as ventricles from the multi-chambered hearts of vertebrates: (1) isovolumic contraction, (2) ventricular emptying, (3) isovolumic relaxation and (4) ventricular filling. The area enclosed by the PV loop provides a measure of stroke work and when multiplied by heart rate provides an assessment of cardiac work. This initial examination of PV loops from a single-ventricle decapod crustacean demonstrates the utility of this technique to further elucidate the cardiac mechanics and energetics of this system, and in particular during times of physiological stress.

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Hypoxic exposure experienced during sensitive developmental periods can shape adult physiological capabilities and define regulatory limits. Tadpole shrimp were reared under normoxic (19-21 kPa O(2)), moderate (10-13 kPa O(2)) or severe (1-3 kPa O(2)) hypoxic conditions to investigate the influence of developmental oxygen partial pressure (P(O(2))) on adult metabolic, respiratory and cardiovascular physiology. Developmental P(O(2)) had no effect on metabolic rate or metabolic response to hypoxic exposure in adults. All rearing groups decreased O(2) consumption as water P(O(2)) decreased. Heart rate, stroke volume and cardiac output were independent of P(O(2)) down to 5 kPa O(2) in all rearing groups. Below this, cardiac output was maintained only in tadpole shrimp reared under severe hypoxic conditions. The enhanced ability to maintain cardiac output was attributed to an increase in hemoglobin concentration and O(2)-binding affinity in those animals. Oxygen-delivery potential was also significantly higher in the group reared under severe hypoxic conditions (1,336 microl O(2) min(-1)) when compared with the group reared under normoxic conditions (274 microl O(2) min(-1)). Differences among the rearing groups that were dependent on hemoglobin were not considered developmental effects because hemoglobin concentration could be increased within seven days of hypoxic exposure independent of developmental P(O(2)). Hypoxia-induced hemoglobin synthesis may be a compensatory mechanism that allows tadpole shrimp to regulate O(2) uptake and transport in euryoxic (O(2) variable) environments. The results of this study indicate that increased hemoglobin concentration, increased O(2)-binding affinity and transient decreases in metabolic demand may account for tadpole shrimp hypoxic tolerance.

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The cardiovascular system performs key physiological functions even as it develops and grows. The ontogeny of cardiac physiology was studied throughout embryonic and larval development in the red swamp crayfish Procambarus clarkii using videomicroscopic dimensional analysis. The heart begins to contract by day 13 of development (at 25 degrees C, 20 kPa O2). Prior to eclosion, heart rate (fH) decreases significantly. Previous data suggests that the decrease in cardiac parameters prior to hatching may be due to an oxygen limitation of the embryo. Throughout development, metabolizing mass and embryonic oxygen consumption primarily increased while egg surface area remains constant. The limited area for gas exchange of the egg membrane, in combination with the increasing oxygen demand of the embryo could result in an inadequate diffusive supply of oxygen to developing tissues. To determine if the decrease in cardiac function was the result of an internal hypoxia experienced during late embryonic development, early and late stage embryos were exposed to hyperoxic water (PO2 = 40 kPa O2). The fH in late stage embryos increased significantly over control values when exposed to hyperoxic water suggesting that the suppression in cardiac function observed in late stage embryos is likely due to a limited oxygen supply.

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Hemoglobin (Hb) is a highly conserved protein that provides a vital link between environmental oxygen and its use and/or storage within an organism. While ubiquitous among vertebrates, Hb occurs frequently in invertebrate phyla as well. Many arthropod species use the copper-binding pigment hemocyanin, but unique in this phylum are the branchiopod crustaceans, which express Hb. Branchiopod Hb concentration and structure are exquisitely sensitive to environmental oxygen availability. Hemoglobin concentration and oxygen-binding affinity increase with decreasing oxygen tension in Daphnia, Artemia and Triops. The change in binding affinity is attributed to differential Hb subunit expression in Daphnia and Artemia but remains unclear for Triops. This is the first study to demonstrate developmental plasticity of Hb subunit expression in a notostracan, Triops longicaudatus, reared under conditions of varying oxygen availability. In response to variable oxygen environments, T. longicaudatus differentially express four primary Hb subunits ranging between 30 and 34 kDa, with normoxic-reared animals expressing primarily the heavier subunits, and hypoxic-reared animals expressing increased proportions of the lower molecular mass subunits. Moreover, differential Hb subunit expression is induced upon transfer of normoxic-reared adults to a hypoxic environment, such that the distribution of Hb subunits in the transferred adults becomes similar to that of hypoxic-reared animals. Two-dimensional gel electrophoresis and follow-up analyses revealed several isoforms of Hb subunits that may represent differential gene expression and/or post-translational modification. Unlike Daphnia and Artemia, the Hb hypoxic response in Triops is not reversible in that there was no significant decrease in Hb concentration or change in Hb subunit expression pattern when hypoxic-reared adults were transferred to a normoxic environment.

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There are few intraspecific studies relating physiological parameters to body mass. This study relates scaling of ionic regulation and respiratory parameters with body mass in crayfish (Procambarus clarkii). These animals were chosen because of their direct development, spanning four orders of magnitude in body mass. Usually, these animals are hyperregulators and must maintain hemolymph electrolyte levels above those in the ambient freshwater. This is especially important in the postmolt, when ion imbalance can occur. Maintaining hemolymph ion levels above ambient involves active processes that are independently related to metabolic rate, ventilation, and circulation. Therefore, this study investigates relationships among size and ionic regulation, heart rate, and ventilation in crayfish, spanning a size range of 0.003-24 g. Postmolt net ion uptake of Ca, titratable base, Na, Cl, and NH4 increase with body mass (positive allometry) with slopes of 0.92, 0.79, 0.90, 0.84, and 0.87, respectively. Between 72% and 97% of variation in ionic regulation was related to body mass. The slopes differed from each other for Ca and titratable base but not for Na, Cl, and NH4. For heart rate and ventilation rate, different relationships were derived for animals smaller and larger than 0.01 g (between first and third instar). Animals larger than 0.01 g show a negative allometric relationship between heart rate and body size ([body mass](0.15)), while smaller animals show positive allometry with body size, but only 29% of variation in heart rate is explained by body size alone. For ventilation rates, the negative allometry with body size for animals larger than 0.01 g is present, but less than 15% of variation in ventilation rate is explained by size, while for smaller animals the size dependency disappears. Based on these results, predictions of physiological parameters such as ionic regulation based on body size are useful in crayfish, but estimates of respiratory parameters and body size should be used with caution.

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The cardiovascular system is the first system to become functional in a developing animal and must perform key physiological functions even as it develops and grows. The ontogeny of cardiac physiology was studied throughout embryonic and larval developmental stages in the red swamp crayfish Procambarus clarkii using videomicroscopic dimensional analysis. The heart begins to contract by day 13 of development (at 25 degrees C, 20 kPa O(2)). Cardiac output is primarily regulated by changes in heart rate because stroke volume remains relatively constant throughout embryogenesis. Prior to eclosion, heart rate and cardiac output decreased significantly. Previous data suggest that the decrease in cardiac parameters prior to hatching may be due to an oxygen limitation to the embryo. Throughout development, metabolizing mass and embryonic oxygen consumption increased, while egg surface area remained constant. The surface area of the egg membrane is a constraint on gas exchange; this limitation, in combination with the increasing oxygen demand of the embryo, results in an inadequate diffusive supply of oxygen to developing tissues. To determine if the decrease in cardiac function was the result of an internal hypoxia experienced during late embryonic development, early and late-stage embryos were exposed to hyperoxic water (PO(2) = 40 kPa O(2)). Heart rate in late-stage embryos exposed to hyperoxic water increased significantly over control values, which suggests that the suppression in cardiac function observed in late-stage embryos is due to a limited oxygen supply.

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Adult crayfish have a neurogenic heart which is modulated via inputs from the central nervous system and neurohormones, which act on the cardiac ganglion or directly on the myocardium. This study investigates the ontogeny of cardiac regulation by exploring the temporal sequence of cardiac sensitivity to injections of cardioactive neurohormones (proctolin, serotonin and octopamine) and the neurotransmitter gamma-aminobutyric acid. The cardiac response (delta in heart rate, stroke volume, or in cardiac output) to each neurohormone at each developmental stage was assessed. The observed response elicited by each cardioactive drug was stage dependent and changed as the animals progressed from embryonic through larval and juvenile periods. During early developmental stages, octopamine, serotonin, and proctolin (10(-9)-10(-3) M) did not result in a modulation of stroke volume, yet in later developmental stages they caused significant increases in stroke volume, at comparable concentrations. Early developmental stages are capable of regulating cardiac function, however, the mechanisms appear to be quite different from those used by adults. Evidence is also provided to support the hypothesis that cardiac function is initiated prior to the establishment of an adult-like regulatory system.

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The purpose of this study was to develop a long-acting injectable formulation of bG-CSF for veterinary use. However, in order to achieve sustained in vivo activity it was first necessary to stabilize the protein at the injection site. Preformulation studies, as well as literature, suggest that bG-CSF aggregates at neutral pH ranges (i.e., pH 6-8) and at temperatures of approximately 40 degrees C. Therefore, bG-CSF will not retain its activity for an extended period of time at the injection site. During this study we determined that HEPES buffer has a very significant impact on protein stability as well as on biological performance. Recombinant bovine granulocyte colony stimulating factor (rbG-CSF) was formulated in 1 M HEPES buffer for subcutaneous injection into cows. bG-CSF formulated in 1 M HEPES buffer resulted in sustained in vivo activity of bG-CSF compared to the "control" formulation (control formulation: 5% mannitol, 10 mM acetate buffer, 0.004% tween-80, pH 4). White blood cell (WBC) count was used as a marker to evaluate in vivo activity of the formulation. WBC numbers remained above a threshold value for only 24-30 h for the control formula. However, when bG-CSF was formulated in 1 M HEPES, the WBC remained above threshold for 3 days or 72 h. Formulating bG-CSF in 1 M HEPES at pH 7.5 also resulted in greater solution stability. This was surprising since bG-CSF is intrinsically not stable at neutral pH. The effect of 1 M HEPES on the T(M) (temperature at maximum heat flow on calorimetry scan) of bG-CSF was determined by microcalorimetry. In the absence of 1 M HEPES buffer the T(M) was 48 degrees C (onset approximately 40 degrees C), while bG-CSF formulated in 1 M HEPES buffer has a T(M) of 59 degrees C (onset approximately 50 degrees C). Similar organic buffers, such as MOPS, HEPPS, TES, and tricine, also resulted in improved solution stability as well as in sustained in vivo activity. The dramatic effect of these buffers on stability and biological performance of bG-CSF is not well understood. One hypothesis is that the electrostatic interaction between the zwitterionic form of these buffers and bG-CSF provides stabilization against denaturation.

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Crustacean embryonic and larval systems offer a unique and valuable tool for furthering our understanding of both developmental processes and physiological regulatory mechanisms. The diverse array of developmental patterns exhibited by crustaceans allows species choice to be based on the specific questions being investigated, where defined larval forms are chosen based on their developmental pattern, degree of maturation or regulatory capabilities. However, this great diversity in developmental patterns, as well as crustacean diversity, can also confound ones ability to define or identify species for investigation. These issues are addressed and suggestions put forth to clarify some of the problems. The complexity and overlapping nature of adult cardio-regulatory systems makes teasing them apart difficult. Embryonic and larval systems exhibit varying degrees of regulatory complexity depending on developmental stage and ontogenetic pattern. This can allow complex adult regulatory systems to be teased apart temporally, as the developing animal builds regulatory pathways. Equally important is the nature of crustacean larvae; many undergo dramatic metamorphoses in cases where the larvae have adaptations to environments different to those of the adult. During environmental transitions physiological adaptations to immediate change should take precedence over long-term adult adaptations. It is therefore possible to look at physiological responses as a function of developmental/environmental adaptation, independent of adult functions.

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The CSAT Methamphetamine Treatment Project (MTP) is a multisite study with a two-fold purpose: to assess the feasibility and outcomes generated by a technology transfer of the Matrix treatment model for methamphetamine (MA) abuse into several community-based treatment programs, and specifically to compare outcomes of treatment as usual at each site with outcomes of the Matrix model, as implemented in each site. The study comprises seven sites, geographically situated in Hawaii, Northern and Southern California, and Montana. This article presents a demographic description of the cohort, and describes patterns of drug use, abuse, and related problems among the 169 participants recruited in the first six months of the study, from April through September 1999. Specific analyses presented include: demographic composition of the sample with respect to gender, age, ethnicity, education completed, employment status, and income; primary drug used, and mean percent of days using various drugs including MA, alcohol, and marijuana; and percent of sample reporting various routes of drug administration. Mean baseline Addiction Severity Index composite scores are presented that describe medical, employment, alcohol, drug, legal, family/social, and psychiatric status for the sample. Also presented here are comparisons of this preliminary population to other populations reported in the literature. This early subset of MTP participants is similar to other methamphetamine-abusing populations described in the literature in age, years of education, income, and mean years of use. However, because of its multisite structure and the locations of its constituent sites, the MTP population has greater variation in ethnic makeup than do populations from other studies, offering an opportunity to provide useful new information about drug use patterns and treatment responses in populations not previously studied.

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The Methamphetamine Treatment Project is a multisite trial that compares the effectiveness of eight models of outpatient treatment for methamphetamine dependence to that of the Matrix model. These eight "treatment-as-usual" models represent diverse approaches developed in a variety of settings to serve markedly different populations. The theoretical foundations of these treatments are described as well as the settings in which they are delivered. To facilitate comparisons, details are presented with respect to frequency of group and individual sessions, duration of treatment, therapist qualifications, and access to ancillary services. The populations served by these programs vary with respect to race and ethnicity. Most programs serve primarily non-Hispanic Caucasians, but some programs serve significant proportions of Hispanics, Asians, Pacific Islanders, and Native Americans. Usual route of administration of methamphetamine also varies by site, with snorting, smoking, and injecting each reported as the most common route of administration at one or more sites. The Minnesota model and cognitive-behavioral approaches are most commonly used in these programs, although contingency management and psychodynamic approaches are also represented. The intensive phase of treatment ranges between four and 24 weeks; the number of hours per week of client contact varies between one and 13. This trial will provide the opportunity to test the effectiveness of a wide range of treatments currently in use in community settings.

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The passage of a barium meal (15 % by mass) was followed through the digestive system of the blue crab Callinectes sapidus by flash-freezing crabs at set intervals, followed by radiography of specimens. Food moved from the oesophagus into the stomach region within 15 min. After 1-2 h, food was visible in the midgut, at 6 h it had reached the hindgut, and material was still present in the stomach at this time. The stomach was emptied between 8 and 10 h after feeding, and the entire digestive system was cleared of material after 18 h. A pulsed-Doppler flowmeter was used to monitor cardiac variables and arterial haemolymph flows during a 4 h control and 24 h postprandial period. Heart rate increased immediately upon food detection and remained elevated for 16-18 h after food ingestion. There was no significant change in stroke volume of the heart, and total cardiac output increased significantly and remained elevated above pre-feeding levels for 24 h after feeding. There was no change in haemolymph flow through the anterior or posterior aorta, but flow increased in the sternal, anterolateral and hepatic arteries. These changes in haemolymph flow reflected the use of the chelae and mouthparts in feeding, contraction of the visceral muscle surrounding the gut system and mobilisation of enzymes from the hepatopancreas. There was also a postprandial increase in the rate of oxygen uptake (apparent specific dynamic action). The rate of oxygen consumption (M(dot)(O2)) reached maximal levels 4 h after feeding and decreased slowly thereafter, reflecting the increased use of oxygen in digestion and absorption.

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Central obesity is an important risk factor for chronic disease. Its etiology remains unclear. We examined whether anger and hostility, ie, psychological attributes that influence cardiovascular morbidity and mortality, prospectively predict central visceral obesity across 13 years. Visceral adipose tissue (VAT) was determined by x-ray computed tomography (CT) at the L4-L5 disc space in a population-based sample of 157 postmenopausal Healthy Women Study participants. Standardized tests were completed to measure separately trait anger (anger frequency and intensity), style of anger expression (holding anger in and expressing it outwardly), and hostile (mistrustful) attitudes. The higher the VAT score, the higher the trait anger and anger-out scores measured 13 years earlier (Ps < .04) and the higher the concurrent hostile attitudes score (P < .02). Moreover, the higher the VAT score, the greater the increase in trait anger over the study period (P < .03). Trait anger and hostility predicted VAT independent of fasting insulin levels, although both predicted an increase in fasting insulin over time. Women were categorized into three groups according to the distribution of the average percent increase in trait anger and in weight across the study period, respectively. The mean VAT scores increased with the likelihood of being in the highest tertile of increasing trait anger (means: 129.1, 131.1, and 155.8, P < .048) and in the highest tertile of increasing weight (means: 122.4, 131.1, and 162.2, P < .003). The association between a high trait anger score and VAT remained significant, controlling for weight gain. We conclude that hostile attributes, fasting insulin, and weight gain in midlife may contribute to the development of VAT in healthy Caucasian women.

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Reports focusing on the behavioral responses of crabs to exposure to low salinity have involved choice chamber experiments or quantification of changes in activity. In addition to describing changes in locomotor activity in four species of crabs of differing osmoregulatory ability, the present study describes six behaviors: increased movement of the mouthparts, cleaning of the mouthparts with the chelae, cleaning of the antennae and antennules with the maxillipeds, flicking of the antennae, retraction of the antennules, and extension of the abdomen. Callinectes sapidus and Carcinus maenas are classed as efficient osmoregulators, and in general, showed an increase in these behaviors with decreasing salinity. Cancer magister, a weak regulator, and Libinia emarginata, an osmoconformer, exhibited these behaviors to a lesser degree and became inactive in the lower salinities, tending to adopt an isolation-type response. The differences in behaviors between the species correlated closely with previously reported changes in cardiovascular function and hemolymph flow. These overt reactions are discussed in relation to the osmoregulatory physiology and ecology of each crab species.

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As the blue crab Callinectes sapidus moves from sea water to fresh water, the 'exposed' chemosensory dendrites in the olfactory sensilla (aesthetascs) undergo changes in length that are positively correlated with environmental salinity. In this study, we demonstrate the following. (1) The responses of the olfactory receptor cells of freshwater-acclimated crabs are reduced relative to those of seawater-acclimated animals, but increase with a time course comparable to the increase in dendrite length when these crabs are transferred to sea water. (2) The olfactory response of seawater-acclimated crabs is lost and the chemosensory dendrites osmotically ablated if the aesthetascs are acutely exposed to low salinity. However, maintaining iso-osmotic conditions with mannitol preserves both the physiological response and the structural integrity of the dendrites. (3) The flux of [14C]thiocyanate and 22Na between the hemolymph and sensillar lymph of the aesthetascs indicates continuity between these fluid compartments. (4) There is a net efflux of Na+ from the hemolymph through the aesthetascs in freshwater-acclimated crabs, and measurements of electrical potential across the antennules suggest that this efflux largely derives from passive diffusion. (5) Dendrites in the aesthetascs of crabs acclimated to brackish water are intermediate in length between those of freshwater- and seawater-acclimated animals. Together, our findings suggest that, at low salinities, the efflux of Na+ (and probably other ions) from the hemolymph generates an ionic/osmotic microenvironment within the aesthetascs that sustains the structural and functional integrity of the olfactory dendrites. We propose that the length of these dendrites, and consequently the olfactory response, is constrained by the distance over which this microenvironment can be effectively maintained.

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Arterial hemolymph flow was measured in restrained crayfish (Procambarus clarkii) and lobsters (Homarus americanus). Implanted pulsed Doppler flow transducers were used to measure arterial flows in the anterior aorta, posterior aorta, sternal artery, lateral artery, ventral thoracic artery and ventral abdominal artery, allowing determination of flow simultaneously in several arteries over a period of 4 days. Calculated Doppler hemolymph flow showed a strong correlation (P<0.05) with 'pumped' hemolymph flow as determined by in situ calibration. Arterial flow patterns remained constant during quiet conditions. In crayfish, cardiac output was 7.5±1.1 ml min-1 (252 ml kg-1 min-1), of which the anterior aorta received 1.3±0.15 ml min-1 (20.1±4.0 %), the posterior aorta received 0.8±0.1 ml min-1 (12.3±2.7 %) and the sternal artery received 5.2±1.4 ml min-1 (67.5±37.0 %). Mean heart frequency at rest was 125.6±5.2 beats min-1 and stroke volume was 0.06±0.01 ml beat-1 (1.98 ml kg-1 beat-1). In lobsters, cardiac output was 60.8±4.4 ml min-1 (93.6±6.8 ml kg-1 min-1), with the anterior aorta receiving 7.8±0.8 ml min-1 (12.8±2.7 %), the lateral arteries receiving 0.6±0.2 ml min-1 (1.0±0.5 %), the posterior aorta receiving 12.6±1.0 ml min-1 (20.7±3.3 %) and the sternal artery receiving 38.9±4.1 ml min-1 (64.0±13.4 %). Flows in the branches of the sternal artery were 0.3±0.05 ml min-1 (0.5±2 %) in the ventral abdominal artery and 4.0±0.1 ml min-1 (6.5±0.3 %) in the ventral thoracic artery. Lobster heart rate was 82.5±2.9 beats min-1 and stroke volume was 0.7±0.05 ml beat-1. Periods of constant hemolymph flow were interrupted by tail flexions (abdominal flexion) and, in lobsters, periods of cardiac/respiratory pause. Tail movement increased flow (peak height and minimum flow values) in both crayfish and lobsters, although the general wave form of hemolymph flow and pressure did not change. In lobsters, periodic respiratory pauses were observed during which all arteries received hemolymph, despite the low heart rate.