Effects of different artificial diets on commercial honey bee colony performance, health biomarkers, and gut microbiota.

BACKGROUND: Honey bee colonies managed for agricultural pollination are highly dependent on human inputs, especially for disease control and supplemental nutrition. Hives are routinely fed artificial "pollen substitute" diets to compensate for insufficient nutritional forage in the environment. The aim of this study was to investigate the effects of different artificial diets in a northern California, US commercial beekeeping operation from August through February. This time period represents an extended forage dearth when supplemental nutrition is used to stimulate late winter colony growth prior to almond pollination in the early spring. A total of 144 honey bee colonies were divided into 8 feeding groups that were replicated at three apiary sites. Feeding groups received commercial diets (Global, Ultra Bee, Bulk Soft, MegaBee, AP23, Healthy Bees), a beekeeper-formulated diet (Homebrew), or a sugar negative control. Diets were analyzed for macronutrient and amino acid content then evaluated with respect to honey bee colony population size, average bee weight, nutrition-related gene expression, gut microbiota abundance, and pathogen levels. RESULTS: Replicated at three apiary sites, two pollen-containing diets (Global and Homebrew) produced the largest colonies and the heaviest bees per colony. Two diets (Bulk Soft and AP23) that did not contain pollen led to significantly larger colonies than a sugar negative control diet. Diet macronutrient content was not correlated with colony size or health biomarkers. The sum of dietary essential amino acid deficiencies relative to leucine content were correlated with average bee weight in November and colony size used for almond pollination in February. Nutrition-related gene expression, gut microbiota, and pathogen levels were influenced by apiary site, which overrode some diet effects. Regarding microbiota, diet had a significant impact on the abundance of Bifidobacterium and Gilliamella and trended towards effects on other prominent bee gut taxa. CONCLUSIONS: Multiple colony and individual bee measures are necessary to test diet efficacy since honey bee nutritional responses are complex to evaluate. Balancing essential amino acid content relative to leucine instead of tryptophan may improve diet protein efficiency ratios. Optimization of bee diets could improve feed sustainability and agricultural pollination efficiency by supporting larger, healthier honey bee colonies.

Population structure, gene flow, and sex-biased dispersal in the reticulated flatwoods salamander (Ambystoma bishopi): Implications for translocations.

Understanding patterns of gene flow and population structure is vital for managing threatened and endangered species. The reticulated flatwoods salamander (Ambystoma bishopi) is an endangered species with a fragmented range; therefore, assessing connectivity and genetic population structure can inform future conservation. Samples collected from breeding sites (n = 5) were used to calculate structure and gene flow using three marker types: single nucleotide polymorphisms isolated from potential immune genes (SNPs), nuclear data from the major histocompatibility complex (MHC), and the mitochondrial control region. At a broad geographical scale, nuclear data (SNP and MHC) supported gene flow and little structure (F ST = 0.00-0.09) while mitochondrial structure was high (ΦST = 0.15-0.36) and gene flow was low. Mitochondrial markers also exhibited isolation by distance (IBD) between sites (p = 0.01) and within one site (p = 0.04) while nuclear markers did not show IBD between or within sites (p = 0.17 and p = 0.66). Due to the discordant results between nuclear and mitochondrial markers, our results suggest male-biased dispersal. Overall, salamander populations showed little genetic differentiation and structure with some gene flow, at least historically, among sampling sites. Given historic gene flow and a lack of population structure, carefully considered reintroductions could begin to expand the limited range of this salamander to ensure its long-term resilience.

A Novel Application of Head Tracking Data in the Analysis and Assessment of Operational Cervical Spine Range of Motion for Army Aviators.

INTRODUCTION: Neck pain among rotary-wing aviators has been established as an important issue in the military community, yet no U.S. Army regulation defines exactly what cervical spine range of motion (CROM) is adequate for flight. This lack of regulation leaves flight surgeons to subjectively determine whether an aviator affected by limited CROM is fit to maintain flight status. The U.S. Army Aeromedical Research Laboratory is conducting a study among AH-64 and UH-60 pilots to define CROM requirements in simulated and actual flight using optical head tracking equipment. Presented here is a preliminary analysis of head position data from a pilot and co-pilot in two AH-64 missions. METHODS: Maintenance data recorder (MDR) files from two AH-64 missions were provided by the Apache Attack Helicopter Project Management Office. Data were filtered down to three-dimensional pilot and co-pilot head position data and each data point was analyzed to determine neck posture. These neck postures were then categorized as neutral, mild, and severe for flexion/extension, lateral bending, and twist rotation postural categories. RESULTS: Twist rotation postures reached 90 degrees, particularly early in the flight; additionally, a few instances of 90-degree lateral bends were observed. Co-pilots spent more time than pilots in mild and severe twist rotation posture for both flights. Co-pilots also spend a high percentage of time in mild flexion and twist rotation. CONCLUSION: This investigation provides a proof of concept for analysis of head tracking data from MDR files as a surrogate measure of neck posture in order to estimate CROM requirements in rotary-wing military flight missions. Future studies will analyze differences in day and night flights, pilot versus co-pilot CROM, and neck movement frequency.

Hydrogel Contact Lens Water Content is Dependent on Tearfilm pH.

Introduction: Based on clinical inferences, investigators theorized in situ soft lens hydration was linked to the precorneal tearfilm pH. Methods: Forty-one myopic subjects at Fort Rucker, AL, USA were fitted with one of two types of extended-wear soft contact lenses, and were followed quarterly for a period of 33 mo. The anterior soft contact lens surface pH was measured in situ, while the in vitro lens water content was measured immediately after lens removal, using a hand-held refractometer on one lens, and a gravimetric means of hydration measurement on the other lens. Results: The in situ pH increased logarithmically across extended wearing time, reaching an asymptote at approximately 5 d' wearing time at a pH of 7.45 ± 0.03. Lens water content was shown to similarly decrease at an inversely logarithmic rate, leveling off at 4-5 d' extended wearing time. Both means of hydration assessment correlated well with each other across days' extended wearing time (R = 0.98; p < 0.0001). Discussion: A log-log dual conversion yielded significantly different linear slopes (p < 0.001), based on a multifactorial analysis of both lens types, by the pH, and by their water content. The differing ionic status of each material accentuated their varied polar attraction characteristics. Two soft lenses, identical in all patient-based parameters, could provide differing oxygen availability, as well as differing physical fits in patients of identical physical characteristics, as a result of their unique tearfilm pH differences. Conclusion: The in situ hydrogel lens water content is directly dependent on the precorneal tearfilm pH.

A Novel, Inexpensive Method to Monitor, Record, and Analyze Breathing Behavior During Normobaric Hypoxia Generated by the Reduced Oxygen Breathing Device.

OBJECTIVES: Since hypoxia remains one of the most important physiological hazards the aviation environment poses, military aviators are trained to recognize symptoms of hypoxia in order to implement appropriate safety procedures and countermeasures when hypoxia occurs. A widely used commercial instrument for hypoxia training, demonstration, and research is the Reduced Oxygen Breathing Device (ROBD). Here we describe a novel, inexpensive method to use the ROBD's breathing loop pressure (BLP) to measure respiration rate, a critically important response parameter for hypoxia. METHODS: The ROBD can be controlled by a computer to export several variables including BLP, via the ROBD's RS232 port. An archived database was reanalyzed to assess the BLP data. New instrumentation added independent measures of respiration and expired oxygen and carbon dioxide; these measures were integrated with the ROBD output. RESULTS: Analysis of the archived data showed that the BLP reflected realistic breathing patterns. The new instrumentation integrated well with the ROBD, and independently supported the potential of the BLP as a valid measure of respiration. DISCUSSION: The ROBD's BLP data may provide a basis for a reliable, sensitive measure of respiration that is available at no additional cost.

Blast Wave Dynamics at the Cornea as a Function of Eye Protection Form and Fit.

A shock tube and anthropomorphic headforms were used to investigate eye protection form and fit using eyewear on the Authorized Protective Eyewear List in primary ocular blast trauma experiments. Time pressure recordings were obtained from highly linear pressure sensors mounted at the cornea of instrumented headforms of different sizes. A custom shock tube produced highly reliable shock waves and pressure recordings were collected as a function of shock wave orientation and protective eyewear. Eyewear protection coefficients were calculated as a function of a new metric of eyewear fit. In general, better protection was correlated with smaller gaps between the eyewear and face. For oblique angles, most spectacles actually potentiated the blast wave by creating higher peak pressures at the cornea. Installing foam around the perimeter of the spectacle lens to close the gap between the lens and face resulted in significantly lower pressure at the cornea. In conclusion, current eye protection, which was designed to reduce secondary and tertiary blast injuries, provides insufficient protection against primary blast injury.