Energy dynamics of subyearling Chinook salmon reveal the importance of piscivory to short‐term growth during early marine residence

Variation in prey quantity and quality can influence growth and survival of marine predators, including anadromous fish that migrate from freshwater systems. The objective of this study was to examine the energy dynamics of subyearling Chinook salmon (Oncorhynchus tshawytscha) following freshwater emigration. To address this objective, a population of Chinook salmon and their marine prey were repeatedly sampled from June to September over 2 years in coastal waters off Oregon and Washington. Subyearlings from the same population were also reared under laboratory conditions. Using a bioenergetics model evaluated in the laboratory, we found that growth rate variability in the field was associated more with differences in northern anchovy (Engraulis mordax) consumption and less with variation in diet energy density or ocean temperature. Highest growth rates (2.43–3.22% body weight/day) occurred in months when anchovy biomass peaked, and the timing of peak anchovy biomass varied by year. Our results support a general pattern among subyearling Chinook salmon occurring from Alaska to California that feeding rates contribute most to growth rate variability during early marine residence, although dominant prey types can differ seasonally, annually, or by ecosystem. In the northern California Current, faster growth appears to be associated with the availability of age‐0 anchovy. Identifying factors that influence the seasonal development of the prey field and regulate prey quantity and quality will improve understanding of salmon growth and survival during early marine residence.     

Canine and feline emphysematous gastritis may be differentiated from gastric emphysema based on clinical and imaging characteristics: Five cases

Gastric pneumatosis is an imaging finding defined as the presence of gas foci in the gastric wall. In humans, this imaging feature can result from one of two separate clinical entities: life‐threatening emphysematous gastritis or clinically benign gastric emphysema. This retrospective case series study describes the clinical and imaging features in five animals diagnosed with spontaneous gastric pneumatosis without gastric dilatation‐volvulus. Three canine and two feline cases of spontaneous gastric pneumatosis were identified on radiographic and ultrasonographic examinations. In addition to gastric pneumatosis, one dog and two cats presented concomitant systemic signs such as lethargy, hematemesis, anemia, or leukocytosis. Two dogs remained asymptomatic or presented mild gastrointestinal signs. Portal gas was described in two dogs and one cat, and pneumoperitoneum in one dog. These features were not considered clinically significant. The dog and two cats with systemic signs were euthanized due to clinical deterioration and diagnosed with emphysematous gastritis. The gastric pneumatosis of both dogs without systemic signs resolved while on medical management without antibiotic therapy. These latter cases were interpreted as consistent with gastric emphysema. Findings from the current study indicated that gastric pneumatosis can occur without gastric dilatation‐volvulus in cats and dogs and that a combination of clinical and imaging characteristics may help to differentiate between potentially life‐threatening emphysematous gastritis and relatively benign gastric emphysema. More studies are needed to determine the etiology and risk factors associated with these conditions.     

The renin‐angiotensin‐aldosterone system and its suppression

Chronic activation of the renin‐angiotensin‐aldosterone system (RAAS) promotes and perpetuates the syndromes of congestive heart failure, systemic hypertension, and chronic kidney disease. Excessive circulating and tissue angiotensin II (AngII) and aldosterone levels lead to a pro‐fibrotic, ‐inflammatory, and ‐hypertrophic milieu that causes remodeling and dysfunction in cardiovascular and renal tissues. Understanding of the role of the RAAS in this abnormal pathologic remodeling has grown over the past few decades and numerous medical therapies aimed at suppressing the RAAS have been developed. Despite this, morbidity from these diseases remains high. Continued investigation into the complexities of the RAAS should help clinicians modulate (suppress or enhance) components of this system and improve quality of life and survival. This review focuses on updates in our understanding of the RAAS and the pathophysiology of AngII and aldosterone excess, reviewing what is known about its suppression in cardiovascular and renal diseases, especially in the cat and dog.     

Production and characterization of fibroin hydrogel using waste silk fibers

The use of natural resources, especially processing wastes, as low cost and environmentally friendly alternative aiming high value-added applications is a subject of broad interest. Since the Brazilian silk production annually generates a large amount of waste during the silk fibers processing, this work explores the preparation and characterization of silk fibroin hydrogels using spinning waste silk fibers from textile processing and the processed ones. Hydrogels were obtained directly by dialyzing silk fibroin solutions against frequent changes of water until the gelation point and then lyophilized and characterized in terms of their morphology, crystallinity, thermal resistance and secondary structure. X-ray diffraction analysis revealed the presence of β-sheet conformation related to sol-gel transition. FT-IR spectra indicated the coexistence of random coil (silk I) and β-sheet (silk II) structures, with predominance of β-sheet conformation for hydrogels from processed silk fibers. From thermogravimetric analysis the presence of β-sheet secondary conformation was demonstrated by a degradation peak around 292 °C for both hydrogels. Freeze-dried hydrogels presented sheet or leaf like morphology and no significant change was observed among the hydrogels from waste silk fibers and processed ones. These characteristics suggest that silk fibroin hydrogels prepared from spinning waste silk fibers and obtained directly by dialysis can be potential candidates for biomaterials application, such as drug delivery systems and for wound dressings.     

Efficiency of 2‐phenoxyethanol and Clove Oil for Reducing Handling Stress in Reared Meagre,Argyrosomus regius (Pisces: Sciaenidae)

The effect of two anesthetics, 2‐phenoxyethanol (2‐PE) and clove oil (COil) were studied in meagre, Argyrosomus regius. This study aimed to determine the adequate dose of anesthesia for different aquaculture procedures, to assess a sedative or stressor effect of low anesthetic concentrations, and to assess the effect of low anesthetic doses at high fish densities for longer periods of time on fish survival and behavior. Anesthetics were tested at different concentrations: 2‐PE at 100, 250, 400, 550, and 700 mg/L; COil at 25, 40, 55, 70, and 85 mg/L. Meagre became anesthetized within 10 min when using concentrations above 250 mg/L for 2‐PE and above 40 mg/L for COil. Deep anesthesia was achieved at 700 and 85 mg/L, for 2‐PE and COil, respectively. The fish did not react when blood was collected at these concentrations. Plasma cortisol and glucose levels were similar between sedated meagre with both 2‐PE – 100 mg/L and COil – 10 mg/L, and the control (not sedated; P > 0.05). This suggests that low concentrations of these anesthetics induce similar stress response as handling without anesthesia during routine activities. No mortality was registered when meagre was maintained at high densities with low concentrations of each anesthetic for 2 h.     

Validation of an electrothermal atomization atomic absorption spectrometry method for quantification of total chromium and chromium(VI) in wild mushrooms and underlying soils

An ETAAS method was validated to quantify total Cr and Cr(VI) in mushrooms and the underlying soils. The method includes a sample pretreatment for total Cr dissolution using a wet acid digestion procedure and a selective alkaline extraction for Cr(VI). The limits of detection were, expressed in microg/L, 0.15 and 0.17 for total Cr and Cr(VI), respectively. The linearity ranges under the optimized conditions were 0.15-25.0 and 0.17-20.0 microg/L for total Cr and Cr(VI), respectively. The limits of quantification were, expressed in microg/g of dry weight, 0.0163 and 0.0085 for total and hexavalent chromium, respectively. The precision of the instrumental method for total Cr and Cr(VI) was lower than 1.6%, and for the analytical method, it was lower than 10%. The accuracy of the method for Cr(VI) quantification was evaluated by the standard additions method, with the recoveries being higher than 90% for all of the added concentrations. For total Cr, certified reference materials (lichen CRM 482 and soil sample NCS ZC73001) were used. An interference study was also carried out in a mushroom simulated matrix, and it was verified that the deviations of the expected values were lower than 4.0% for both total Cr and Cr(VI). The validated method was applied to the evaluation of total Cr and Cr(VI) in 34 wild mushrooms and 34 respective underlying soil samples collected in two different regions of Portugal (Beira Interior and TrAs-os-Montes), with different locations regarded as noncontaminated or contaminated areas. The species were identified by a mycologist and subdivided into 10 genera and 15 species: Amanita (rubescens, muscaria, and ponderosa), Boletus (regius), Lactarius (deliciosus, vellereus, and piperatus), Suillus (granulatus and luteus), Tricholoma (acerbum), Agaricus (sylvicola), Volvariella (gloiocephala), Lecopaxillus (giganteus), Macrolepiota (procera), and Psilocybe (fascicularis). The mean values found for total Cr were 1.14 and 1.11 microg/g of dry weight, and for Cr(VI), the mean values were 0.103 and 0.143 microg/g of dry weight for cap and stalk, respectively. For soils, the mean concentrations found were, for total Cr, 84.0 microg/g and, for Cr(VI), 0.483 microg/g. The bioconcentration factors (BCFs) based on dry weight for cap and stalk were determined, and the values found, for both total Cr and Cr(VI), were always <1, although for hexavalent chromium, the BCFs were 10 times higher than for total chromium.