Risk of Sperm Competition Mediates Copulation Duration, but not Paternity, of Male Burying Beetles

Males should increase their investment in ejaculates whenever they are faced with an increased risk of sperm competition. Burying beetles (Nicrophorus vespilloides), insects that breed on small vertebrate carcasses, offer an ideal model with which to examine sperm allocation tactics because females typically mate with many males prior to laying eggs. Males compete directly for control of carcasses, and males losing such contests often become satellites, lurking in the vicinity of the carcass and attempting surreptitious copulations with the resident female. We predicted that both the dominant resident male and the satellite male would increase their sperm allocation in the presence of the other, but that relative to dominant males, satellite males would allocate a greater number of sperm per ejaculate. We employed a repeated-measures design in which two full-sib rival males, differing only in their dominance status, were each mated a single time to a previously-inseminated female under two conditions, once in the absence of their rival and once in the presence of their rival. Satellite males exhibited longer copulation durations than dominant resident males when both males were present on a carcass. Copulation durations of dominant males did not differ in the presence or absence of satellite males. Contrary to expectation, the increased copulation durations of satellite males did not result in a greater share of paternity relative to dominant males. The absence of any discernible effect of increased copulation durations on paternity in satellite males could be due to post-copulatory preferences of females or, alternatively, satellite males may require longer durations of copulation to transfer the same amount of sperm as dominant males.     

Male Reproductive Tactics in an Explosive Breeding Toad Population

American toad (Bufo amencanus) males use one of two differentreproductive tactics. Some males are stationary and call. Othersare silent and mobile. Based on field studies, I developed acomputer program that simulates the behavior of females andmales to determine the probability of mating success of malesengaging the different tactics and the factors that effect malereproductive success. Field studies indicate that non-calling males can be successful.Non-calling males were more numerous and smaller than callingmales. Population size changed greatly both between and withinnights. Contact rates for non-calling males were greater thanthose for calling males. The results of the preliminary simulations indicate that malemating success is a function of the population size and theoperational sex ratio. In small populations, contact rate hasno effect on male success. The effect of contact rate on malesuccess has not been tested in large populations. In large populations,mating success is also a function of the ratio of calling tonon-calling males. Generally, in small populations (n > 20)calling males are more successful than non-calling males. Inlarge populations (n > 40) the success of noncalling malesis equal to or greater than the success of calling males.     

Basic Fuchsin as an Indicator in Endo's Medium

The writer has made an investigation of various samples of basic fuchsin for use in the Endo medium for differentiating the bacteria of the colon-typhoid group. Various different concentrations of the fuchsin samples have been used in making the media. The conclusions are as follows:

American made fuchsins differ markedly in their alcohol solubility properties. They contain materials which are very readily soluble in 95% alcohol, but which are precipitated by sodium sulphite.

This precipitation may be prevented by increasing the dilution of the fuchsin in alcohol.

In order to secure more dependable results in the use of decolorized basic fuchsin as an indicator in Endo Agar, it is advisable to test the fuchsin in different dilutions in alcohol in order to secure a completely decolorized solution. It is also advisable to carefully test those fuchsins which decolorize only in high dilutions with a known organism in Endo agar before relying on it as a satisfactory indicator for the presence of sewage organisms.     

Culturability as an Indicator of Succession in Microbial Communities

Successional theory predicts that opportunistic species with high investment of energy in reproduction and wide niche width will be replaced by equilibrium species with relatively higher investment of energy in maintenance and narrower niche width as communities develop. Since the ability to rapidly grow into a detectable colony on nonselective agar medium could be considered as characteristic of opportunistic types of bacteria, the percentage of culturable cells may be an indicator of successional state in microbial communities. The ratios of culturable cells (colony forming units on R2A agar) to total cells (acridine orange direct microscopic counts) and culturable cells to active cells (reduction of 5-cyano-2,3-ditolyl tetrazolium chloride) were measured over time in two types of laboratory microcosms (the rhizosphere of hydroponically grown wheat and aerobic, continuously stirred tank reactors containing plant biomass) to determine the effectiveness of culturabilty as an index of successional state. The culturable cell:total cell ratio in the rhizosphere decreased from approximately 0.25 to less than 0.05 during the first 30-50 days of plant growth, and from 0.65 to 0.14 during the first 7 days of operation of the bioreactor. The culturable cell:active cell ratio followed similar trends, but the values were consistently greater than the culturable cell:total cell ratio, and even exceeded I in early samples. Follow-up studies used a cultivation-independent method, terminal restriction fragment length polymorphisms (TRFLP) from whole community DNA, to assess community structure. The number of TRFLP peaks increased with time, while the number of culturable types did not, indicating that the general decrease in culturability is associated with a shift in community structure. The ratio of respired to assimilated C-14-labeled amino acids increased with the age of rhizosphere communities, supporting the hypothesis that a shift in resource allocation from growth to maintenance occurs with time. Results from this work indicate that the percentage of culturable cells may be a useful method for assessing the successional state of microbial communities.     

Time Allocation during the Reproductive Season in Vicuñas

Vicuñas (Vicugna vicugna) are wild South American camelids that live in high-altitude grasslands (Puna). Their social organization is based on family and bachelor groups. The amount of time they allocated to walking, running, lying, grazing and alert behaviour was studied in Abrapampa, northwestern Argentina, during the 1988–1990 reproductive seasons. Females and yearlings spent significantly more time grazing, and less time walking, running and alert than territorial males and bachelors. This result suggests that females maximized the time spent foraging to fulfil the energetic demands of reproduction. The alertness of the territorial males increased and the grazing decreased with the number of females in the families, suggesting that males that incurred a higher cost of lost feeding time through vigilance activities increased their mating success.     

Variation in Male Reproductive Longevity across Traditional Societies

Most accounts of human life history propose that women have short reproductive spans relative to their adult lifespans, while men not only remain fertile but carry on reproducing until late life. Here we argue that studies have overlooked evidence for variation in male reproductive ageing across human populations. We apply a Bayesian approach to census data from Agta hunter-gatherers and Gambian farmers to show that long post-reproductive lifespans characterise not only women but also males in some traditional human populations. We calculate three indices of reproductive ageing in men (oldest age at reproduction, male late-life reproduction, and post-reproductive representation) and identify a continuum of male reproductive longevity across eight traditional societies ranging from !Kung, Hadza and Agta hunter-gatherers exhibiting low levels of polygyny, early age at last reproduction and long post-reproductive lifespans, to male Gambian agriculturalists and Turkana pastoralists showing higher levels of polygyny, late-life reproduction and shorter post-reproductive lifespans. We conclude that the uniquely human detachment between rates of somatic senescence and reproductive decline, and the existence of post-reproductive lifespans, are features of both male and female life histories, and therefore not exclusive consequences of menopause.     

Rate-Temperature Curves as an Unambiguous Indicator of Biological Activity in Soil

Experiments are described in which we used a mass spectrometer to monitor O₂ uptake of enclosed soil samples as a function of temperature. We found that an Arrhenius plot of the rate of O₂ uptake showed pronounced local maxima attributable to biological activity, whereas similar plots of rates obtained with abiotic soils yielded straight lines. This procedure thus provides a basis for distinguishing biological from chemical activity for reactions, such as O₂ uptake, that can occur via either biological or chemical pathways.     

Enlargement of Cerebral Ventricles as an Early Indicator of Encephalomyelitis

Inflammatory disorders of the central nervous system such as multiple sclerosis and acute disseminated encephalomyelitis involve an invasion of immune cells that ultimately leads to white matter demyelination, neurodegeneration and development of neurological symptoms. A clinical diagnosis is often made when neurodegenerative processes are already ongoing. In an attempt to seek early indicators of disease, we studied the temporal and spatial distribution of brain modifications in experimental autoimmune encephalomyelitis (EAE). In a thorough magnetic resonance imaging study performed with EAE mice, we observed significant enlargement of the ventricles prior to disease clinical manifestation and an increase in free water content within the cerebrospinal fluid as demonstrated by changes in T₂ relaxation times. The increase in ventricle size was seen in the lateral, third and fourth ventricles. In some EAE mice the ventricle size started returning to normal values during disease remission. In parallel to this macroscopic phenomenon, we studied the temporal evolution of microscopic lesions commonly observed in the cerebellum also starting prior to disease onset. Our data suggest that changes in ventricle size during the early stages of brain inflammation could be an early indicator of the events preceding neurological disease and warrant further exploration in preclinical and clinical studies.     

P-Aminodimethylaniline Monohydrochloride as an Indicator of Microbial Action on Fats

Flooding p-aminodimethylaniline monohydrochloride on fat emulsion agar inoculated with certain types of microorganisms frequently results in marked color changes in the fat globules. It is shown in this paper that the colors result from the increased solubility in fat and fatty acids of this dye as it becomes oxidized. Some of the acids oxidize the dye on contact and therefore color very quickly; fats become colored only when some other agent oxidizes the dye. The characteristic color reactions with certain fats and fatty acids are described for various degrees of oxidation of the dye; this suggests the explanation for the colors observed in the inoculated globules flooded with this dye. A table is included showing the colors in globules of oil that were inoculated with 39 pure cultures of bacteria.     

Mortality as an Indicator of Aging: Possibilities and Limitations

Biophysics - Abstract—Using data gathered from 40 countries throughout a historical period covering two and a half centuries, we studied the peculiarities of age-related changes in the aging...     

Pepper Mild Mottle Virus as an Indicator of Fecal Pollution

Accurate indicators of fecal pollution are needed in order to minimize public health risks associated with wastewater contamination in recreational waters. However, the bacterial indicators currently used for monitoring water quality do not correlate with the presence of pathogens. Here we demonstrate that the plant pathogen Pepper mild mottle virus (PMMoV) is widespread and abundant in wastewater from the United States, suggesting the utility of this virus as an indicator of human fecal pollution. Quantitative PCR was used to determine the abundance of PMMoV in raw sewage, treated wastewater, seawater exposed to wastewater, and fecal samples and/or intestinal homogenates from a wide variety of animals. PMMoV was present in all wastewater samples at concentrations greater than 1 million copies per milliliter of raw sewage. Despite the ubiquity of PMMoV in human feces, this virus was not detected in the majority of animal fecal samples tested, with the exception of chicken and seagull samples. PMMoV was detected in four out of six seawater samples collected near point sources of secondary treated wastewater off southeastern Florida, where it co-occurred with several other pathogens and indicators of fecal pollution. Since PMMoV was not found in nonpolluted seawater samples and could be detected in surface seawater for approximately 1 week after its initial introduction, the presence of PMMoV in the marine environment reflects a recent contamination event. Together, these data demonstrate that PMMoV is a promising new indicator of fecal pollution in coastal environments.Existing wastewater treatment practices are not always effective at removing the large number of pathogens (bacteria, protists, and viruses) present in human feces (17, 42, 47-49, 51). Therefore, wastewater discharges into the environment can have a negative impact on human health. Recreational waters throughout the United States are monitored for the presence of fecal pollution as a means of limiting public exposure to pathogens in areas impacted by wastewater discharges (44). The presence of pathogenic viruses in aquatic environments is an important parameter to consider in the evaluation of water quality. However, the bacterial indicators currently used to detect fecal contamination, such as fecal coliforms and enterococci, often do not correlate with the presence of feces-associated viruses and other pathogens (5, 10, 26, 33, 37, 51). In response, several researchers have proposed the use of viral indicators as a more effective method for monitoring wastewater contamination and the associated risks to public health (11, 14, 31).To date, the majority of the proposed viral indicators of fecal pollution are enteric viruses transmitted via the fecal-oral route (4). Enteric viruses present in raw sewage (including members of the families Adenoviridae, Caliciviridae, Picornaviridae, and Reoviridae and of the genus Anellovirus) have been used in several previous studies to identify fecal pollution in the environment (7, 8, 11, 12, 13, 18, 19, 27, 28, 32-36, 38, 50, 51). Of the enteric viruses that have been used as indicators, only the adenoviruses were ubiquitously found in raw sewage samples collected throughout the United States (41). Picobirnaviruses and Torque teno virus are abundant in raw sewage from some regions and thus have also been proposed as indicator viruses (15, 41). However, one potential problem with the use of human viruses as indicators is that their abundance in wastewater depends on the degree of infection and shedding in the human population at any given time.In addition to viruses infecting humans, other viruses shed in feces may be useful for indicating wastewater pollution. The plant pathogen Pepper mild mottle virus (PMMoV) was the most abundant virus found in a metagenomic survey of RNA viruses from human feces (52). PMMoV is a positive-sense, single-stranded RNA virus that belongs to the Tobamovirus genus and infects hot, bell, and ornamental peppers (Capsicum spp.) (9). The nonenveloped, rod-shaped PMMoV virions are extremely stable (9) and have been demonstrated to retain their infectivity for plants after passage through the human gut (52). PMMoV originates from processed pepper products (e.g., hot sauce and curry) and is excreted in human feces at concentrations of 1 million to 1 billion viruses per g (dry weight) (52). Since the presence of PMMoV in human feces is dietary in origin, this plant pathogen may be more abundant in the healthy human population than viruses that cause human disease.This study analyzed the presence of PMMoV in raw sewage and treated wastewater samples collected from wastewater treatment facilities throughout the coastal United States. To determine if PMMoV is a human-specific indicator useful for tracking the source of fecal pollution, fecal samples from numerous animals were tested for this virus. Finally, the presence of PMMoV in marine environments exposed to wastewater was determined and compared to that of other microbial indicators. The results of this work demonstrate that PMMoV is a promising indicator of fecal pollution.     

Nematode Autofluorescence and Its Use as an Indicator of Viability

Representatives of 15 nematode genera were viewed with 450-490-nm epi-illumination and found to autofluoresce. The autofluorescence was limited to 1-5-μm-d globules in the intestinal cells of live nematodes. When adult Pratylenchus penetrans or Caenorhabditis elegans were killed with formaldehyde, freezing, or heat, autofluorescence dispersed throughout the body. Mixed stages of P. penetrans were killed by freezing at several different temperatures. Estimates of survival based on autofluorescence dispersal matched estimates based on mobility more closely than did estimates based on the vital stain, eosin-y.     

Body Acceleration as Indicator for Walking Economy in an Ageing Population

Background

In adults, walking economy declines with increasing age and negatively influences walking speed. This study aims at detecting determinants of walking economy from body acceleration during walking in an ageing population.

Methods

35 healthy elderly (18 males, age 51 to 83 y, BMI 25.5±2.4 kg/m2) walked on a treadmill. Energy expenditure was measured with indirect calorimetry while body acceleration was sampled at 60Hz with a tri-axial accelerometer (GT3X+, ActiGraph), positioned on the lower back. Walking economy was measured as lowest energy needed to displace one kilogram of body mass for one meter while walking (WCost_min, J/m/kg). Gait features were extracted from the acceleration signal and included in a model to predict WCost_min.

Results

On average WCost_min was 2.43±0.42 J/m/kg and correlated significantly with gait rate (r² = 0.21, p<0.01) and regularity along the frontal (anteroposterior) and lateral (mediolateral) axes (r² = 0.16, p<0.05 and r² = 0.12, p<0.05 respectively). Together, the three variables explained 46% of the inter-subject variance (p<0.001) with a standard error of estimate of 0.30 J/m/kg. WCost_min and regularity along the frontal and lateral axes were related to age (WCost_min: r² = 0.44, p<0.001; regularity: r² = 0.16, p<0.05 and r² = 0.12, p<0.05 respectively frontal and lateral).

Conclusions

The age associated decline in walking economy is induced by the adoption of an increased gait rate and by irregular body acceleration in the horizontal plane.     

Nest Building as an Indicator of Health and Welfare in Laboratory Mice

The minimization and alleviation of suffering has moral and scientific implications. In order to mitigate this negative experience one must be able to identify when an animal is actually in distress. Pain, illness, or distress cannot be managed if unrecognized. Evaluation of pain or illness typically involves the measurement of physiologic and behavioral indicators which are either invasive or not suitable for large scale assessment. The observation of nesting behavior shows promise as the basis of a species appropriate cage-side assessment tool for recognizing distress in mice. Here we demonstrate the utility of nest building behavior in laboratory mice as an ethologically relevant indicator of welfare. The methods presented can be successfully used to identify thermal stressors, aggressive cages, sickness, and pain. Observation of nest building behavior in mouse colonies provides a refinement to health and well-being assessment on a day to day basis.     

Methanobrevibacter ruminantium as an Indicator of Domesticated-Ruminant Fecal Pollution in Surface Waters

A PCR-based assay (Mrnif) targeting the nifH gene of Methanobrevibacter ruminantium was developed to detect fecal pollution from domesticated ruminants in environmental water samples. The assay produced the expected amplification product only when the reaction mixture contained DNA extracted from M. ruminantium culture, bovine (80%), sheep (100%), and goat (75%) feces, and water samples from a bovine waste lagoon (100%) and a creek contaminated with bovine lagoon waste (100%). The assay appears to be specific and sensitive and can distinguish between domesticated- and nondomesticated-ruminant fecal pollution in environmental samples.     

Copeptin as an Indicator of Hemodynamic Derangement and Prognosis in Liver Cirrhosis

Background

Advanced liver cirrhosis is associated with systemic hemodynamic derangement leading to the development of severe complications associated with increased mortality. Copeptin is a stable cleavage product of the precursor of arginine vasopressin, a key-regulator in hemodynamic homeostasis. Copeptin is currently considered a reliable prognostic marker in a wide variety of diseases other than cirrhosis. The present study aimed to assess copeptin, both experimentally and clinically, as a potential biomarker of hemodynamic derangement and to evaluate its prognostic significance in cirrhosis.

Materials and Methods

Two studies were executed: 1) in 18 thioacetamide-induced cirrhotic rats and 5 control rats, plasma copeptin and hemodynamic measurements were performed, 2) in 61 cirrhotic patients, serum copeptin concentration was measured in samples collected at time of registration at the waiting list for liver transplantation. In 46 patients, also a second copeptin measurement was performed during follow-up while registered at the waiting list for liver transplantation. To determine the association of serum copeptin and clinical data with outcome, Cox proportional hazard regression analysis and Kaplan Meier analysis were performed.

Results

Plasma copeptin concentration was significantly higher in cirrhotic rats than in controls (1.6 ± 0.5 vs. 0.9 ± 0.1 pmol/L, p< 0.01) and was negatively correlated to the mean arterial blood pressure (r = -0.574, p = 0.013). In cirrhotic patients, serum copeptin concentration was high [11.0 (5.2–24.0) pmol/L] and increased significantly during the time of registration at the waiting list for liver transplantation. MELD and MELD-sodium score were significantly correlated to serum copeptin [MELD: (r = 0.33, p = 0.01), MELD-sodium: (r = 0.29, p = 0.02)], also at time of the second copeptin measurement [MELD and MELD-sodium: r = 0.39, p< 0.01]. In cirrhotic humans, serum copeptin concentration was significantly associated with outcome, independently of the MELD and MELD-sodium score. Patients with a low serum copeptin concentration at time of registration at the liver transplant waiting list had significantly better transplant-free survival rates at 3, 6 and 12 months of follow-up as compared to those with a high serum copeptin concentration (Log-rank: p< 0.01, p< 0.01 and p = 0.02 respectively).

Conclusions

Circulating copeptin levels are elevated in rats and humans with cirrhosis. Copeptin is independently associated with outcome in cirrhotic patients awaiting liver transplantation.