Does Fusarium‐caused seed mortality contribute to Bromus tectorum stand failure in the Great Basin?

Bromus tectorum (cheatgrass, downy brome) is an important invader in western North America, dominating millions of hectares of former semi‐arid shrubland. Stand failure or ‘die‐off’ is relatively common in monocultures of this annual grass. The study reported here investigated whether soil‐borne pathogens could be causal agents in die‐offs. Soils from two die‐off areas and adjacent B. tectorum stands were used in a glasshouse experiment with sterilised and non‐sterilised treatments. Soil sterilisation did not increase emergence, which averaged 80% in both die‐off and non‐die‐off soils. Seedling biomass was higher in die‐off soils, probably due to increased nitrogen availability. Fusarium was isolated from 80% of killed seeds in non‐sterilised soil treatments. In pathogenicity tests with 16 Fusarium isolates, host seeds incubated under water stress (?1.5MPa for 1 week prior to transfer to free water) suffered over twice the mortality of seeds incubated directly in free water (25–83% with water stress vs. 5–43% without water stress). These results suggest that soil‐borne Fusarium could play a role in B. tectorum stand failure in the field, but that low water stress conditions in the glasshouse experiment were not conducive to high levels of disease. Pathogenic Fusarium isolates were obtained from seeds planted in both die‐off and non‐die‐off soils, suggesting that microenvironmental factors that affect levels of water stress might be as important as relative abundance of soil‐borne pathogens in mediating spatial patterns of disease incidence in the field.     

The hidden value of artisanal fisheries in Honduras

Declining fisheries catches are a global trend, with management failing to keep pace with growth in fishing effort and technological advances. The economic value of Honduras’ catches was estimated within the industrial and artisanal sectors. Catches were found to be 2.9 times greater than the official statistics between 1950 and 2015. The merging of industrial and artisanal catch data masked the decline in industrial catches and hid the strong growth of artisanal fisheries. In 1996, annual artisanal fisheries landed catches surpassed the industrial fishery sector, and in 2000, the annual net value of artisanal fisheries eclipsed the value of the industrial fisheries. These data highlight the importance of artisanal fisheries in Honduras and challenge the long‐held belief that the industrial sector contributes more to the national economy. The global paucity of fisheries data highlights the need for comprehensive strategies to collect more detailed and accurate fisheries data.     

Comparison of stocking time and density on Gulf Killifish growth in freshwater ponds

The Gulf Killifish (Fundulus grandis) is a popular baitfish and a candidate for commercial‐scale production. For inland production, ponds may need to be stocked at different times and densities to meet market demands. Therefore, in Experiment 1, juveniles were stocked into freshwater ponds at a density of 25,000 fish/ha, with two cohorts (mean total length (TL) = 3.92; 3.52 cm) stocked 1 month apart and evaluated for 12 weeks. Cohort 1 had a lower overall survival (40%) than cohort 2 (79%); with no difference between mean final TL (8.46; 8.00 cm); reaching a market size of 6 cm in 22 days and 32 days respectively. In Experiment 2, juveniles (mean TL = 3.16; 3.23 cm) were stocked into freshwater ponds at two densities (25,000 fish/ha and 50,000 fish/ha). Mean final TL was greater in the lower stocking density (8.68 cm) than the higher stocking density (8.20 cm); with no differences in survival between treatments (75; 72%) respectively. Lower stocking and higher stocking densities reached a market size of 6 cm in 29 and 31 days respectively. These results suggest that multiple cohorts can be stocked and grown to market size in one season at a stocking density of 50,000 fish/ha.     

Seasonal and sex differences in energy reserves of red snapper <Emphasis Type="Italic">Lutjanus campechanus</Emphasis> on natural and artificial reefs in the northwestern Gulf of Mexico

To evaluate the energetic condition of red snapper inhabiting natural and artificial reefs in the Gulf of Mexico, the liver-somatic index (LSI) and muscle tissue caloric density (CD) were measured for fish collected between September 2011 and October 2013. Liver energy reserves were highest in spring and decreased during summer, with greater LSI values at natural reefs in spring. While female red snapper LSI was greater than males at the natural reefs, indicating a larger energetic investment for spawning, it did not differ between males and females at the artificial reefs. Females at natural reefs have the ability to invest more energy in reproduction than females at artificial reefs, which is reflected in larger female LSI values at the natural reefs. Caloric density was highest in winter and decreased through fall at the natural reefs, with the opposite trend observed at artificial reefs. Muscle energy reserves are likely utilized for gonad development, while stored liver energy is utilized during and after spawning. Female red snapper at natural reefs can exhibit greater energy reserves, and thus a higher energetic condition than females at artificial reefs. Recognizing that energetic condition differs between habitats could enhance future red snapper stock assessments.     

Photoperiod and seasonal influences on the growth of turkey hens

1. The influence of photoperiod and time of year on the growth of hen turkeys was investigated.

2. Photoperiod treatments consisted of computer simulations of day lengths which occur naturally in the spring and autumn of the year. Both photoperiod treatments were given to hens in the autumn and spring.

3. Data were collected for growth evaluations at 2‐ to 4‐week intervals to 16 weeks of age. No significant season × photoperiod interactions occurred.

4. The spring trial resulted in greater body weights and better food conversions (food/gain) than the autumn trial.

5. Simulated autumn daylengths resulted in greater body weights and improved food efficiency at 16 weeks of age compared with simulated spring daylengths.

6. The pattern of growth (period changes) was influenced by season, but not photoperiod.

7. Season and photoperiod both have important and independent influences on the growth of the turkey hen.     

Molecular cloning and characterization of bovine P-selectin glycoprotein ligand-1

Human P-selectin glycoprotein ligand-1 (PSGL-1) is a dimeric membrane mucin expressed on leukocytes that binds selectins. Here, we report that the open reading frame (ORF) of bovine PSGL-1 (bPSGL-1) cDNA is 1284 base pairs in length, predicting a protein of 427 amino acids including an 18-amino-acid signal peptide, an extracellular region with a mucin-like domain, and transmembrane and cytoplasmic domains. The amino acid sequence of bPSGL-1 demonstrated 52, 49 and 40% overall homology to equine, human and mouse, respectively. A single extracellular cysteine, at the transmembrane and extracellular domain junction, suggests a disulfide-bonding pattern. Alignment of bovine with equine, human and mouse PSGL-1 demonstrates high conservation of transmembrane and cytoplasmic domains, but diversity of the extracellular domain, especially in the anionic NH(2)-terminal of PSGL-1, the putative P-selectin binding domain. In the NH(2)-terminal of bPSGL-1, there are three potential tyrosine sulfation sites and three potential threonine O-glycosylation sites, all of which are required for P-selectin binding in human PSGL-1 (hPSGL-1). bPSGL-1 shares only 57% homology in amino acid sequence with the corresponding epitope region which binds the monoclonal antibody PL1 for hPSGL-1, and no cross-reactivity was found in bovine leukocytes. In summary, bPSGL-1 shares homology with hPSGl-1, but has differences in the putative extracellular P-selectin binding domain.