Explore the vast range of titles available.

Animals in northern environments contend with seasonally variable resources and have evolved life histories to cope with the flush of nutrients in summer and scarcity in winter. Ungulates cope with seasonal variation in resources by accreting fat stores when resources are plentiful during the growing season and then mobilizing these stores to meet nutritional requirements when resources are more limited during winter. While this generalization makes sense, previous work has suggested that caribou (Rangifer tarandus spp.) may break this rule; however, previous works have suffered various limitations that leave this question unanswered. As part of a larger study to understand the role of nutrition as a potential factor limiting the Mulchatna Caribou Herd (MCH) in southwestern Alaska, we initiated a longitudinal study in which we captured the same individual caribou twice annually in autumn and late winter. We aimed to test the hypothesis that winter nutrition limited the MCH and predicted that caribou would lose fat between late autumn and late winter. During captures, we determined body fat percentage of lactating, adult females using validated ultrasonography and manual palpation techniques, and determined pregnancy status in late winter using transabdominal ultrasonography. Repeated measures indicated lactating females gained body fat over winter, averaging ~2.8 percentage points from 6.1% ± 0.1% (mean ± SE) in autumn to 8.9% ± 0.4% in late winter (z = 5.425, p < 0.001), with maximum individual gains of up to 8.5 percentage points. Our findings provide empirical support for overwinter gains in fat among caribou and indicate that winter nutrition is not limiting the MCH. Our findings illustrate the value of longitudinal studies in ecology, have implications for research designs for studies of nutrition in northern ungulates, and highlight important considerations for caribou relative to unique nutritional aspects of their life history.

The facultative intracellular pathogen Salmonella enterica Typhimurium (STM) resides in a specific membrane-bound compartment termed the Salmonella- containing vacuole (SCV). STM is able to obtain all nutrients required for rapid proliferation, although being separated from direct access to host cell metabolites. The formation of specific tubular membrane compartments, called Salmonella -induced filaments (SIFs) are known to provides bacterial nutrition by giving STM access to endocytosed material and enabling proliferation. Additionally, STM expresses a range of nutrient uptake system for growth in nutrient limited environments to overcome the nutrition depletion inside the host. By utilizing dual fluorescence reporters, we shed light on the nutritional environment of intracellular STM in various host cells and distinct intracellular niches. We showed that STM uses nutrients of the host cell and adapts uniquely to the different nutrient conditions. In addition, we provide further evidence for improved nutrient supply by SIF formation or presence in the cytosol of epithelial cells, and the correlation of nutrient supply to bacterial proliferation.

The spatial distribution of animals has consequences for nutrition, predator–prey dynamics, spread of diseases, and population dynamics in general. Animals must establish a home range to secure adequate resources to fuel their energy needs. Home ranges, therefore, are temporally and spatially dynamic, given the changing requirements of an animal and the availability of resources on the landscape. We used data from two populations of bighorn sheep with contrasting population dynamics following pneumonia epizootics and different habitat quality on their summer range to test the hypothesis that the distribution and size of home ranges are influenced by environmental conditions and reproductive status. We used a combination of data from 768 vegetation transects and remotely sensed metrics to index forage quality of consecutive biweekly home ranges for 27 bighorn sheep, June–August 2019–2021. There were population differences in home range dynamics that were consistent with resource limitations in the population declining in abundance. Animals in both populations increased the size of their home range through the summer in association with declining forage quality indexed by plant phenology. Furthermore, animals in the Whiskey Mountain population without offspring had home ranges more than twice the size of animals with offspring, whereas there were no differences in the home range size between animals with and without offspring in Jackson. We demonstrated that limitations young offspring impose on space use of a mother may have consequences for animals living where larger home ranges are needed to secure adequate resources—sheep on Whiskey Mountain had to travel 1000 m from escape terrain to access the same amount of biomass that the Jackson sheep could access directly adjacent to escape terrain. Forage quality and availability influence movement and space use. In the presence of disease, movement and space use may influence pathogen transmission and persistence. Thus, forage availability may play an indirect role in population dynamics in the presence of disease, which is another line of evidence for how environmental and nutritional conditions may influence population dynamics when coping with disease.

Nutritional limitation is a common phenomenon in nature that leads to trade‐offs among processes competing for limited resources. These trade‐offs are mediated by changes in physiological traits such as growth factors and circulating lipids. However, studies addressing the sex‐specific effect of nutritional deficiency on these physiological variables are limited in birds. We used dietary restriction to mimic the depletion of resources to various degrees and investigated sex‐specific effects on circulating levels of insulin‐like growth factor 1 (IGF‐1) and triglycerides in Japanese quails (Coturnix japonica) subjected to ad libitum, 20%, 30% or 40% restriction of their daily requirement, for 2 weeks. We also explored the association of both physiological variables with body mass and egg production. While dietary restriction showed no effects on circulating IGF‐1, this hormone exhibited a marked sexual difference, with females having 64.7% higher IGF‐1 levels than males. Dietary restriction significantly reduced plasma triglyceride levels in both sexes. Females showed more than six‐fold higher triglyceride levels than males. Triglyceride levels were positively associated with body mass in females while showed not association in males. Overall, our findings revealed sex‐specific expression of physiological variables under dietary restriction conditions, which coincide with body size. Trade‐offs among processes competing for limited resources are mediated by changes in physiological traits such as growth factors and circulating lipids. However, studies addressing the sex‐specific effect of nutritional deficiency on these physiological variables are limited in birds. Our findings reveal a sex‐specific expression of physiological variables under dietary restriction conditions and coincide with body size in Japanese quails.

ABSTRACT Demographic data show many populations of Rocky Mountain (Cervus elaphus nelsoni) and Roosevelt (Cervus elaphus roosevelti) elk have been declining over the last few decades. Recent work suggests that forage quality and associated animal nutritional condition, particularly in late summer and early autumn, influence reproduction and survival in elk. Therefore, we estimated seasonal nutritional condition of 861 female elk in 2,114 capture events from 21 herds in Washington, Oregon, Wyoming, Colorado, and South Dakota from 1998 to 2007. We estimated ingesta‐free body fat and body mass, and determined age, pregnancy status, and lactation status. We obtained estimates for most herds in both late winter–early spring (late Feb–early Apr) and in autumn (Nov–early Dec) to identify changes in nutritional condition of individuals across seasons. Body fat levels of lactating females in autumn were consistently lower than their non‐lactating counterparts, and herd averages of lactating elk ranged from 5.5% to 12.4%. These levels were 30–75% of those documented for captive lactating elk fed high‐quality diets during summer and autumn. Body fat levels were generally lowest in the coastal and inland northwest regions and highest along the west‐slope of the northern Cascades. Adult females in most herds lost an average of 30.7 kg (range: 5–62 kg), or about 13% (range: 2.6–25%) of their autumn mass during winter, indicating nutritional deficiencies. However, we found no significant relationships between spring body fat or change in body fat over winter with winter weather, region, or herd, despite markedly different winter weather among herds and regions. Instead, body fat levels in spring were primarily a function of fat levels the previous autumn. Thinner females in autumn lost less body fat and body mass over winter than did fatter females, a compensatory response, but still ended the season with less body fat than the fatter elk. Body fat levels of lactating females in autumn varied among herds but were unrelated to their body fat levels the previous spring. Within herds, thinner females exhibited a compensatory response during summer and accrued more fat than their fatter counterparts over summer, resulting in similar body fat levels among lactating elk in autumn despite considerable differences in their fat levels the previous spring. Level of body fat achieved by lactating females in autumn varied 2‐fold among herds, undoubtedly because of differences in summer nutrition. Thus, summer nutrition set limits to rates of body fat accrual of lactating females that in turn limited body condition across the annual cycle. Pregnancy rates of 2‐ to 14‐year‐old females ranged from 68% to 100% in coastal populations of Washington, 69% to 98% in Cascade populations of Washington and Oregon, 84% to 94% in inland northwestern populations of Washington and Oregon, and 78% to 93% in Rocky Mountain populations. We found evidence of late breeding, even in herds with comparatively high pregnancy rates. Mean body mass of calves (n = 242) in 3 populations was 75 kg, 81 kg, and 97 kg, representing 55–70% of potential mass for 6‐ to 8‐month‐old calves on high‐quality diets. Mean mass of 11 yearling females caught in autumn was 162 kg, approximately 70% of potential for autumn, and pregnancy rate was 27%. Mean mass of 28 yearlings caught in spring was 163 kg and pregnancy rate was 34%. Our data suggest widespread occurrence of inadequate summer nutrition. Summer ranges of just 3 herds supported relatively high levels of autumn body fat (11–13% body fat) and pregnancy rates (>90%) even among females that successfully raised a calf year after year. Most other summer ranges supported relatively low autumn levels of body fat (5–9% body fat), and reproductive pauses were common (<80% pregnancy rates). Overall, our data failed to support 2 common assumptions: 1) summer and early autumn foraging conditions are typically satisfactory to prevent nutritional limitations to adult fat accretion, pregnancy rates, and calf and yearling growth; and 2) winter nutrition and winter weather are the principal limiting effects on elk productivity. Instead, a strong interaction existed among level of summer nutrition, lactation status, and probability of breeding that was little affected by winter conditions—adequacy of summer nutrition dictated reproductive performance of female elk and growth as well as growth and development of their offspring in the Northwest and Rocky Mountains. Our work signals the need for greater emphasis on summer habitats in land management planning on behalf of elk. © 2013 The Wildlife Society. RESUMEN Los datos demográficos disponibles muestran que las poblaciones de alce de las Montañas Rocosas (Cervus elaphus nelsoni) y de alce de Roosevelt (Cervus elaphus roosevelti) han ido disminuyendo en las últimas décadas. Estudios recientes sugieren que la calidad del forraje y el estado nutricional del alce, especialmente a finales del verano y principios del otoño, influyen en su reproducción y supervivencia. En consecuencia, se decidió estimar el estado nutricional de 861 hembras de alce, en 2114 eventos de captura, de 21 rebaños en Washington, Oregón, Wyoming, Colorado y Dakota del Sur desde 1998 al 2007. Se estimó la grasa corporal (sin incluir el bolo alimentario) y la masa corporal y también se determinó la edad, el estado de embarazo y el estado de lactancia de estos animales. Estas estimaciones fueron obtenidas, para la mayoría de los rebaños, a finales del invierno y principios de la primavera (finales de febrero y principios de abril) así como en otoño (noviembre y principios de diciembre) con el fin de identificar los cambios en el estado nutricional de los individuos a través de las estaciones. En otoño, los niveles de grasa corporal de las hembras que daban de lactar fueron consistentemente más bajos que aquellos de las hembras que no daban de lactar y el promedio de hembras en estado de lactancia varió entre 5.5% y 12.4%. Estos niveles equivalen al 30–75% de aquellos documentados en la literatura para hembras en cautividad, en estado de lactancia y alimentadas con dietas de alta calidad durante el verano y el otoño. Los niveles de grasa corporal fueron generalmente más bajos en regiones costeras y al interior del Noroeste americano, mientras que los niveles más altos fueron observados a lo largo de la ladera occidental de las Cascadas del Norte. Durante el invierno, las hembras adultas en la mayoría de los rebaños perdieron un promedio de 30.7 kg (rango: 5–62 kg), o alrededor del 13% (rango: 2.6–25%) de la masa corporal registrada en otoño, lo que es indicativo de deficiencias nutricionales. Sin embargo, no se encontraron correlaciones significativas entre la grasa corporal registrada en primavera, o el cambio en la grasa corporal durante el invierno, y el clima invernal, la región o el rebaño, a pesar de los diferentes climas invernales entre los rebaños y las regiones. Por otro lado, se observó que los niveles de grasa corporal en la primavera fueron principalmente una función de los niveles de grasa del otoño precedente. Las hembras más delgadas perdieron menos grasa corporal y masa corporal durante el invierno que las hembras más gordas—lo que podría interpretarse como una respuesta compensatoria—pero aún así terminaron la temporada con menos grasa corporal que las hembras más gordas. Los niveles de grasa corporal de las hembras que daban de lactar en otoño variaron entre los rebaños, pero no guardaron ninguna relación con los niveles de grasa corporal de la primavera anterior. Dentro de los rebaños, las hembras más delgadas mostraron una respuesta compensatoria durante el verano y acumularon más grasa que las hembras más gordas a lo largo del verano, dando lugar a similares niveles de grasa corporal entre las hembras que daban de lactar en otoño a pesar de las considerables diferencias en sus niveles de grasa de la primavera anterior. El nivel de grasa corporal adquirido por las hembras que daban de lactar en otoño varió el doble entre los rebaños, sin duda debido a las diferencias en la alimentación durante el verano. Así, el nivel de nutrición alcanzado durante el verano parece haber establecido restricciones en las tasas de acumulación de grasa corporal de las hembras que daban de lactar, lo que a su vez limitó su condición física a través del ciclo anual. Las tasas de embarazo de las hembras de entre 2 a 14 años de edad varió entre 68% y 100% en las poblaciones costeras de Washington, entre 69% y 98% en las poblaciones de Cascade de Washington y Oregón, entre 84% a 94% en las poblaciones del interior del noroeste de Washington y Oregón, y entre 78% y 93% en las poblaciones de las Montañas Rocosas. Se encontró evidencia de reproducción tardía incluso en rebaños con tasas de embarazo relativamente altas. La media de masa corporal de los terneros (n = 242) en tres poblaciones fue de 75, 81 y 97 kg, es decir entre 55% y 70% de la masa potencial de terneros de 6 a 8 meses de edad alimentados con dieta de alta calidad. La media de masa corporal de 11 becerras atrapadas en otoño fue de 162 kg, lo que equivale aproximadamente a 70% de su masa potencial en otoño; su tasa de embarazo fue del 27%. La media de masa corporal de 28 becerras atrapadas en primavera fue de 163 kg y su tasa de embarazo fue del 34%. Nuestros datos sugieren una amplia incidencia de malnutrición durante el verano. Las zonas de alimentación de verano de sólo tres rebaños sustentaron niveles relativamente altos de grasa corporal de otoño (11–13%) y tasas de embarazo (>90%) incluso entre las hembras que lograron criar un ternero año tras año. La mayoría de las otras zonas de alimentación de verano sustentaron niveles de grasa corporal relativamente bajos (5–9%) y en esas zonas las pausas reproductivas fueron comunes (tasas de embarazo <80%). En general, nuestros datos no apoyan dos supuestos comunes: 1) las condiciones de búsqueda de forraje durante el

Alfalfa (Medicago sativa L.) can fix N naturally within soils, which makes alfalfa cultivation useful for enhancing soil fertility while minimizing environmental impacts from pesticides, fertilizers, and soil pollution. To assess the influence of alfalfa cropping on degraded black soil, we determined the nutrient stoichiometry of the soil and soil microbial biomass under four corn cultivation systems at the Harbin Corn Demonstration Base (Heilongjiang, China), which is located in Wujia (126°23′ E, 45°31′ N), Shuangcheng district, Harbin, Heilongjiang Province. The cultivation systems included continuous corn cultivation for more than 30 years (CK), 2 years of alfalfa–corn rotation (AC), three years of alfalfa cropping (TA), and four years of alfalfa cropping (FA). Overall, AC, TA, and FA treatment increased the soil pH, reduced the soil salinity, and increased the organic matter content of the 0–15 cm soil layer. TA and FA presented soil nutrient levels comparable to those of degraded cornfields that were fertilized annually. The TA and FA treatments increased the soil available N:P, soil N:P, and soil C:P ratios. Moreover, TA significantly increased the soil microbial biomass P (SMBP) in the 0–15 cm (surface) soil layer and reduced the soil microbial biomass C (SMBC):SMBP ratio. AC, TA, and FA increased the storage and mineralization rates of soil N and alleviated the microbial P limitations in degraded black soil farmland. Compared with FA, TA resulted in greater improvements in the quality of degraded black soil farmland. The ability of alfalfa to enhance soil fertility makes an important component of sustainable agricultural practices aimed at rehabilitating degraded soils.

To describe a microbial process, two kinds of models can be developed, structured and unstructured models. Contrary to structured models, which take into account some basic aspects of cell structure, their function and composition, no physiological characterization of cells is considered in unstructured models, which only consider total cellular concentration. However, in spite of their simplicity, unstructured models have proven to accurately describe lactic acid fermentation in a wide range of experimental conditions and media. A partial link between cell growth and production, namely the Luedeking and Piret model, is mostly considered by the authors. Culture pH is the main parameter to be considered for model development. Acidic pH leads to inhibitory concentrations of undissociated lactic acid, the main inhibitory component, which causes cessation of growth and then production. On the other hand, pH control at optimal value for LAB growth allows to overcome product inhibition (by the total lactic acid produced or its undissociated part); hence nutritional limitations have to be considered for model development. Nitrogen is mainly involved in cessation of growth, owing to the fastidious nutritional requirements of LAB, while lactic acid production ceased when carbon was exhausted from the medium. The lack of substrate inhibition when usual concentrations of carbon substrate are used should be noted. [PUBLICATION ABSTRACT]

ABSTRACT Carrot is one of the most consumed vegetables in Brazil, where the cultivars currently grown present a high yield potential and nutritional demand, which require constant adjustments in fertilization programs for the crop. This study aimed at determining reference values and diagnostic indices by using the DRIS method in three phenological stages of the carrot crop (around 40 and 70 days after sowing and at harvest), as well as evaluating the possibility of early diagnosis for nutritional limitations. For determining the DRIS norms, a database was obtained from leaf samplings, root yields and leaf contents of N, P, K, Ca, Mg, S, B, Cu, Mn and Zn, in carrot commercial fields. The nutritional limitation order was generated as a function of the fertilization response and optimum range of leaf contents. The reference values for K, Ca, Mg, S and Mn were similar in all sampling times. N, P, B, Cu and Zn varied with the stages sampled, indicating the need to standardize the sampling times for these nutrients. Mn, K and Mg were the most limiting nutrients for the crop growth, while Zn and B were the least limiting. There was a correlation between the diagnoses performed at early stages and those performed at harvest for K, Ca, Mg, S and Mn, indicating the possibility of early diagnosis for the deficiency of these nutrients. RESUMO A cenoura está entre as principais olerícolas consumidas no Brasil, onde as cultivares utilizadas atualmente apresentam elevado potencial produtivo e demanda nutricional, o que exige constantes ajustes dos programas de fertilização da cultura. Objetivou-se determinar valores de referência e índices diagnósticos pelo método DRIS para três fases fenológicas da cultura da cenoura (cerca de 40 e 70 dias após a semeadura e na colheita), bem como verificar a possibilidade de diagnose precoce de limitação nutricional. Para determinação das normas DRIS, obteve-se um banco de dados a partir da amostragem de folhas, produtividade de raízes e teores foliares de N, P, K, Ca, Mg, S, B, Cu, Mn e Zn, em lavouras comerciais de cenoura. A ordem de limitação nutricional foi gerada em função do potencial de resposta à adubação e da faixa ótima dos teores foliares. Os valores referência de K, Ca, Mg, S e Mn mostraram-se semelhantes em todas épocas de amostragem. Os de N, P, B, Cu e Zn variaram, reforçando a ideia de padronização da época de amostragem para esses nutrientes. O Mn, K e Mg foram os nutrientes mais limitantes por deficiência, enquanto Zn e B foram os menos limitantes. Para K, Ca, Mg, S e Mn, há concordância entre a diagnose realizada nas fases precoces e a efetuada na colheita, o que indica possibilidade de diagnose precoce da limitação desses nutrientes.

This study aimed to improve the fermentation efficiency of Kloeckera africana K1, in tequila fermentations. We investigated organic and inorganic nitrogen source requirements in continuous K. africana fermentations fed with Agave tequilana juice. The addition of a mixture of 20 amino-acids greatly improved the fermentation efficiency of this yeast, increasing the consumption of reducing sugars and production of ethanol, compared with fermentations supplemented with ammonium sulfate. The preference of K. africana for each of the 20 amino-acids was further determined in batch fermentations and we found that asparagine supplementation increased K. africana biomass production, reducing sugar consumption and ethanol production (by 30, 36.7 and 45%, respectively) over fermentations supplemented with ammonium sulfate. Therefore, asparagine appears to overcome K. africana nutritional limitation in Agave juice. Surprisingly, K. africana produced a high concentration of ethanol. This contrasts to poor ethanol productivities reported for other non- Saccharomyces yeasts indicating a relatively high ethanol tolerance for the K. africana K1 strain. Kloeckera spp. strains are known to synthesize a wide variety of volatile compounds and we have shown that amino-acid supplements influenced the synthesis by K. africana of important metabolites involved in the bouquet of tequila. The findings of this study have revealed important nutritional limitations of non- Saccharomyces yeasts fermenting Agave tequilana juice, and have highlighted the potential of K. africana in tequila production processes.

Nisin production was improved under nutritional limitation in fed-batch culture of Lactococcus lactis. Nisin titre reached 3887 IU ml(-1) by a slow feeding of sucrose and 4131 IU ml(-1) by slow feeding of nitrogen source, which were, respectively, 64% and 74% above the values in batch culture.