Circadian entrainment by feeding cycles in house sparrows,Passer domesticus

Summary We studied the potential zeitgeber qualities of periodic food availability on the circadian rhythms of locomotor and feeding activity of house sparrows. The birds were initially held in a LD-cycle of 12:12 h, with food restricted to the light phase. After transfer to constant dim light, the birds remained entrained by the restricted feeding schedule. Following an exposure to food ad libitum conditions, the rhythms could be re-synchronized by the feeding cycle. Shortening of the zeitgeber period to 23.5 h resulted in the loss of entrainment in most birds, whereas a longer zeitgeber period of 25 h re-entrained the rhythms of most birds. Although these results prove that periodic food availability can act as a zeitgeber for the circadian rhythms of house sparrows, several features of our data indicate that restricted feeding is only a weak zeitgeber. The pattern of feeding activity prior to the daily time of food access shown under some experimental conditions suggests that anticipation is due to a positive phase-angle difference of the birds' normal circadian system rather than being caused by a separate pacemaker.     

Development and validation of a sensitive ELISA for quantification of secretory IgA in rat saliva and faeces.

Non-invasive measures of immunological markers are an attractive means of stress assessment in laboratory animals. Salivary IgA has been used successfully as a stress marker in the human, and several reports indicate the potential of secretory IgA as a non-invasive measure of stress in animals. The present paper describes the development of an ELISA using commercially available components for the quantification of rat IgA and validation of this assay for the quantification of rat secretory IgA in saliva and faeces. The concentration of IgA in rat saliva varied significantly between duplicate samples obtained from individual rats, and the viscosity and small total volume of rat saliva gave unsatisfactory results for IgA. Faecal IgA was present in high concentrations, and duplicate samples varied by only 2-3%. However, faecal IgA seemed less stable than IgA in other biological compartments, and this finding must be taken into consideration when using quantitative measurements of IgA as a marker of mucous humoral immune status.     

Enhancing Life-Cycle Inventories via Reconciliation with the Laws of Thermodynamics

Abstract: Obtaining reliable results from life-cycle assessment studies is often quite difficult because life-cycle inventory (LCI) data are usually erroneous, incomplete, and even physically meaningless. The real data must satisfy the laws of thermodynamics, so the quality of LCI data may be enhanced by adjusting them to satisfy these laws. This is not a new idea, but a formal thermodynamically sound and statistically rigorous approach for accomplishing this task is not yet available. This article proposes such an approach based on methods for data rectification developed in process systems engineering. This approach exploits redundancy in the available data and models and solves a constrained optimization problem to remove random errors and estimate some missing values. The quality of the results and presence of gross errors are determined by statistical tests on the constraints and measurements. The accuracy of the rectified data is strongly dependent on the accuracy and completeness of the available models, which should capture information such as the life-cycle network, stream compositions, and reactions. Such models are often not provided in LCI databases, so the proposed approach tackles many new challenges that are not encountered in process data rectification. An iterative approach is developed that relies on increasingly detailed information about the life-cycle processes from the user. A comprehensive application of the method to the chlor-alkali inventory being compiled by the National Renewable Energy Laboratory demonstrates the benefits and challenges of this approach.     

Reproductive biology of the endemic goby, Lentipes concolor, from Makamaka'ole Stream, Maui and Waikolu Stream, Moloka'i

Constant pressure in Hawai'i to use limited freshwater resources has resulted in increasing concern for the future of the native stream fauna. Hawaiian freshwater gobies have an amphidromous life cycle with a marine larva period and require streams which flow continuously to the ocean for the critical reproductive periods and during recruitment. As such, the stream fauna is particularly sensitive to any anthropogenic perturbations which disrupt the continuity of stream flows. The objective of this 2-year study was to compare the life cycles of the goby, Lentipes concolor, from a heavily diverted stream on Moloka'i and a relatively undisturbed stream on Maui. In Makamaka'ole Stream, Maui, the population of L. concolor was reproductively active all year with females potentially spawning 2–3 times annually. The timing of spawning did not occur consistently during the wet or dry season but coincided with high stream flow conditions regardless of time-of-year. In Waikolu Stream, Moloka'i, the reproductive pattern was more variable with the number of reproductively active females ranging from 0% to 100%. In general the number of eggs was greater and egg size smaller for female L. concolor in Waikolu Stream than in Makamaka'ole Stream. However, female reproductive condition of L. concolor from Maui was consistently higher than from fish on Moloka'i. Reproduction of L. concolor in Makamaka'ole Stream was correlated with the seasonal pattern of flow rates with peaks in female reproductive condition associated with periods of elevated discharge. No correlation between reproduction and discharge occurred in Waikolu Stream. There were considerable differences between the magnitude of discharge in the two streams. Waikolu Stream experienced prolonged periods of extremely low flows which have become common since the Moloka'i Irrigation System began diverting water from the stream in 1960. In Makamaka'ole Stream, L. concolor was capable of reproducing throughout the year and adjusting fecundity in response to stream flow conditions. In contrast, the population in Waikolu Stream appeared to have a ‘boom or bust’ reproductive pattern; the population had reduced or no reproduction when stream flow conditions reached extreme low levels, but the population succesfully reproduced during higher flow months. The diversion structure in Waikolu Stream has dampened the natural seasonal discharge cycle, exacerbated natural low flow conditions, and increased the likelihood of prolonged periods of extremely low flow. Stream management practices in the Hawaiian Islands must take into account the complex life cycles and sensitivity to variable stream flow conditions of the native fauna. This revised version was published online in July 2006 with corrections to the Cover Date.     

Inhibition of the Multiplication of Vesicular Stomatitis and Newcastle Disease Virus by 2-Deoxy-d-Glucose

The production of infectious vesicular stomatitis (VSV) and Newcastle disease virus can be completely inhibited by 2-deoxy-d-glucose in pyruvate-containing medium, if virus either grown in pyruvate-containing medium or dialyzed against phosphate-buffered saline is used for infection. Under these conditions, the synthesis of all VSV proteins is reduced. VSV RNA, which is synthesized at reduced rates, seems to be unstable. The effect is completely reversible. If virus grown in glucose-containing medium is used for infection, the production of both viruses is not significantly inhibited by 2-deoxy-d-glucose. Under these conditions the production of the VSV glycoprotein is specifically impaired, but does not lead to a marked reduction of the yield of infectious virus.     

Downstream migration of newly-hatched ayu (<Emphasis Type="Italic">Plecoglossus altivelis</Emphasis>) in the Tien Yen River of northern Vietnam

The ayu (Plecoglossus altivelis) is an annual, amphidromous, plecoglossid fish, distributed in Vietnam, China, Taiwan, Korea, and Japan. To date, ayu have been found only in two rivers in northern Vietnam, where little is known about their life history. The Tien Yen River is believed to be the most southwestern habitat for this species. To determine whether newly hatched ayu larvae drift and to understand their downstream migration, intensive surveys were conducted in the Tien Yen River from October to March of 2013–2016. In total, 529 drifting ayu larvae were collected from four of six sampling stations along the river. Thus, ayu reproduction has been confirmed in this river for the first time, where only adult fish had been found previously. However, we did not successfully collect larvae in the eastern branch of the river, which has a hydroelectric dam, suggesting that ayu do not inhabit this branch or else do not reproduce there. The presence of drifting larvae in the western branch from mid-December to late January implies that they spawn from late November to mid-January. Drifting larvae were captured primarily at night, but peak occurrences varied depending upon the day and the sampling station. With the range of body sizes and variable diel abundance patterns, ayu in the Tien Yen River probably employ multiple spawning grounds. This study provides fundamental life history data for the vulnerable ayu populations in northern Vietnam.     

Neutron Diffraction with an Excess-Water Cell

As part of a study of the molecular basis of membrane fusion by enveloped viruses, we have used neutron diffraction to study the lamellar (L_α) to inverse hexagonal (H_II) phase transition in the phospholipid N-methylated dioleoylphosphatidylethanolamine. This lipid was chosen because its phase transitions are particularly sensitive to the presence of agents that have been demonstrated to promote or inhibit membrane fusion. Two different geometries of neutron diffraction were used: small angle scattering (SANS) and a membrane diffractometer. The SANS measurements were carried out on the SWAN instrument at KEK, Japan, using dispersions of multilamellar vesicles (MLVs). The diffractometer measurements used the V1 instrument at BeNSC-HMI, Germany, with a specially-constructed cell that holds a stack of lipid bilayers in an excess-water state. The two approaches are compared and discussed. Although the diffractometer takes considerably longer to collect the data, it records much higher resolution than the SANS instrument. The samples recorded in the excess-water cell were shown to be well aligned, despite the lipids being fully hydrated, allowing for the production of high-resolution data. Trial measurements performed have demonstrated that sample alignment is preserved throughout the L_α to H_II phase transition, thereby opening up possibilities for obtaining high-resolution data from non-lamellar phases.     

Stress, metabolism, and antioxidants in two wild passerine bird species

Antioxidants protect against free-radical damage, and free radicals, in turn, are thought to underlie aging. Thus, measuring antioxidants may aid field ecologists in understanding the physiological mechanisms that underlie life-history trade-offs. Antioxidant levels are known to vary markedly in response to the stress of capture in many birds. These changes in antioxidants could result from regulation (e.g., by stress-related hormones) or consumption (e.g., by an increase in free radicals due to increased metabolic rate). Here we experimentally test the effect of increased metabolic rate on circulating antioxidant and corticosterone concentrations in two wild passerine bird species, house sparrows (Passer domesticus) and gray catbirds (Dumetella carolinensis). We increased metabolic rate via exposure to low ambient temperatures overnight in captivity and measured circulating antioxidant capacity, uric acid, corticosterone, and oxygen consumption in cold-exposed and control individuals. Both species showed increases rather than decreases in all antioxidant parameters overnight, contradicting a consumption-by-energy-expenditure hypothesis. Both positive and negative correlations between antioxidant response and corticosterone response were occasionally but not consistently present, refuting a generalized regulation-by-corticosterone hypothesis. High baseline uric acid predicted diminished response of corticosterone and all antioxidants. Thus, high uric acid may reflect recent stress, poor condition, or a compensatory response. Relationships among metabolic rate, antioxidants, and corticosterone differed qualitatively between the species.     

Males of a single-brooded tropical bird species do not show increases in testosterone during social challenges

The challenge hypothesis poses that in socially monogamous vertebrates, males increase circulating testosterone in response to aggressive challenges to promote intense and persistent aggression. However, in bird species that raise only a single brood during short breeding seasons as well as those with essential male parental care, males lack the well-documented testosterone response to social challenges. We tested male behavioral and hormonal responses to social challenges in a neotropical bird species, the buff-breasted wren (Thryothorus leucotis), which is single-brooded with extensive male parental care, but in contrast to most species studied to date, has a long breeding season. We presented live female, male, and paired decoys with song playback for 30 min during pre-breeding and breeding periods. Males responded aggressively to all intruders, but male decoys elicited somewhat weaker responses overall. Responses to female decoys were most intense during pre-breeding, whereas pair decoys elicited stronger responses at breeding. Plasma testosterone concentrations did not differ between challenged and unchallenged males, or among males exposed to different decoys or during different seasons. Plasma corticosterone in pre-breeding males was higher in challenged than unchallenged males and varied positively with the duration of social challenge. Circulating dehydroepiandrosterone concentrations were similar in challenged and unchallenged males, but correlated positively with the proportion of time males spent in close proximity to the decoy. Both testosterone and corticosterone results support recent findings, suggesting that brood number and essential male care, but not breeding-season length, may be important determinants of male hormonal responsiveness during aggressive interactions.     

Nodulation of native woody legumes in Hong Kong, China

Woody legumes can play an important role in forest restoration on degraded land but the knowledge of woody legumes has lagged behind their uses. This study is a pioneer investigation to explore the ability of native woody legumes to form root nodules and fix nitrogen in Hong Kong. Nine sites of different habitat types were surveyed during both wet and dry seasons for two years. Young plants of woody legumes along studied transects were excavated. The patterns of nodulation and nodule morphology were recorded and the nitrogen fixing ability was tested by acetylene-reduction-assay. Twenty-eight species in 16 genera were examined, of which 20 species were nodulating and eight non-nodulating, including all six species in the Caesalpinioideae. Five species were new records to the world’s nodulation inventory. Bowringia callicarpa was a new species and genus examined, which was non-nodulating. The overall nodulation pattern was consistent with previous studies. Nodulation was more profuse in some shrub species while inconsistent in most tree species. Species with higher proportion of nodulated individual plants also tended to have more nodules in each plant. Spherical nodules were common in shrub and woody climber species whilst tree species usually had woody indeterminate nodules. Seasonal difference in the amount of senescent nodules was noted in most species. All the nodules tested by acetylene-reduction-assay were effectively nitrogen-fixing, with nitrogenase activity ranging from 4 μmol C₂H₄ g^?1 h^?1 to 20 μmol C₂H₄ g^?1 h^?1, which was comparable to other tropical tree species. The findings in nodulation pattern and nitrogen fixing ability of these species are essential in their application in forest restoration on degraded lands.