Oedipus complex in an Antarctic fur seal pup?

We present the first evidence of a possible case of the Oedipus complex in a non-primate. An Antarctic fur seal pup, Arctocephalus gazella, unsuccessfully directed what appeared to be copulatory behaviour towards its own mother on several occasions. A herding sub-adult bull chased the pup from the female, which strengthens our suggestion that it was copulatory behaviour we witnessed. This seemed to constitute innocent sexual play with elements of the Oedipus complex rather than coercion because the female was not stressed nor did the pup possess the physical strength to coerce the female.     

Commodity specific rates of temporal discounting: Does metabolic function underlie differences in rates of discounting?

Discounting rates vary as a function of commodity type. Previous studies suggest five potential characteristics of the commodity that could explain these differences: type of reinforcer (primary or secondary), if the commodity is perishable, if the commodity is satiable, if the commodity can be directly consumed, and immediacy of consumption. This paper suggests that these characteristics may best be viewed as related to a more fundamental characteristic: metabolic processing. In order to explore the possibility that metabolic processing underlies changes in discount rates, the difference in discounting between food, money, music CDs, DVDs, and books are compared. Music CDs, DVDs, and books share many characteristics in common with food, including gaining value through a physiological process, but are not directly metabolized. Results are consistent with previous findings of commodity specific discount rates and show that metabolic function plays a role in determining discount rates with those commodities that are metabolized being discounted at a higher rate. These results are interpreted as evidence that the discount rate for different commodities lies along a continuum with those that serve an exchange function rather than a direct function (money) anchoring the low end and those that serve a direct metabolic function capping the high end (food, alcohol, drugs).     

Intraspecific differences in the diet of Antarctic fur seals at Nyrøysa, Bouvetøya

Intraspecific differences in the diets of many species of pinnipeds are to be expected in view of the great differences in morphology, life history and foraging behaviour between the sexes of many species. We examined the diet of the Antarctic fur seal population at Bouvetøya, Southern Ocean, to assess intersexual differences. This was made possible by the analysis of prey remains extracted from scats and regurgitations collected in areas used primarily by one or the other sex. The results indicate that both males and females feed primarily on Antarctic krill Euphausia superba with several species of fish and squid being taken, likely opportunistically given their prevalence. Significant differences were identified in the frequency of occurrence of otoliths in scats and the percentage numerical abundance of the major fish prey species in the diet. Adult males ate a smaller quantity of fish overall, but ate significantly more of the larger fish species. The greater diving capabilities of males and the fact that they are not limited in the extent of their foraging area by having to return regularly to feed dependant offspring may play a role in the differences found between the diets of males and females. Additionally, females might be more selective, favouring myctophids because they are richer in energy than krill. The absence of major differences in the diet between the sexes at this location is likely due to the high overall abundance of prey at Bouvetøya.     

Provisioning and growth rates of nestling Fulmars Fulmarus glacialis: stochastic variation or regulation?

The pattern of chick feeding in the Fulmar Fulmarus glacialis at St Kilda, Scotland, was examined by repeated weighing of chicks throughout 14 consecutive days during the first half of the chick-rearing period in 1994. After correcting for metabolic weight losses, the sizes of positive mass increments between weighings were used to assess meal sizes and feeding frequency for each chick. Individual meals fed to chicks averaged 80.8 g (s.d. ± 21.0 g), or approximately 10% of adult mass. Each chick received 0 to 4 meals per day, with an average of 1.9 meals per chick per day, giving an average interval of around 25 h between meals delivered by each parent. The distribution of time intervals between feeds for each chick (whether single or double meals) followed a negative exponential function with a maximum value of 80 h. These results are not compatible with the idea that the purpose of large fat deposits in procellariiform chicks is to guarantee survival over long intervals between feeds. Over 14 days, the chicks' mean daily food requirements for zero-growth increased from 98 g to 160 g. This corresponded with an increase in feeding frequency but not meal size. Chicks with lower scores for body condition after feeding by both parents received more meals during the subsequent 16 h and had shorter intervals to the next feed, indicating that adults regulated feeding frequency in accordance with chick condition at the previous feed. This does not agree with the hypothesis that lipid accumulation by nestling Procellariiformes is a response to stochastic variation in food delivery associated with an absence of regulation. In view of the diversity of growth and feeding patterns present among the Procellariiformes, it is possible that lipid accumulation in this group does not have a unitary explanation.     

Ascent exhalations of Antarctic fur seals: a behavioural adaptation for breath-hold diving?

Novel observations collected from video, acoustic and conductivity sensors showed that Antarctic fur seals consistently exhale during the last 50-85% of ascent from all dives (10-160 m, n > 8000 dives from 50 seals). The depth of initial bubble emission was best predicted by maximum dive depth, suggesting an underlying physical mechanism. Bubble sound intensity recorded from one seal followed predictions of a simple model based on venting expanding lung air with decreasing pressure. Comparison of air release between dives, together with lack of variation in intensity of thrusting movement during initial descent regardless of ultimate dive depth, suggested that inhaled diving lung volume was constant for all dives. The thrusting intensity in the final phase of ascent was greater for dives in which ascent exhalation began at a greater depth, suggesting an energetic cost to this behaviour, probably as a result of loss of buoyancy from reduced lung volume. These results suggest that fur seals descend with full lung air stores, and thus face the physiological consequences of pressure at depth. We suggest that these regular and predictable ascent exhalations could function to reduce the potential for a precipitous drop in blood oxygen that would result in shallow-water blackout.     

Invasive and native Rhododendron ponticum populations: is there evidence for genotypic differences in germination and growth?

Previous studies have shown that the invasive spread of Rhododendron ponticum in the British Isles is influenced by the more favourable environmental conditions in the new territory than in the species' home range. In this study, we asked whether the species' invasion success might also involve a genotypic background for higher growth and germination rates in invasive populations. We tested the hypotheses that invasive populations have higher absolute germination rates, germinate faster and exhibit higher growth rates. We present data from greenhouse and climate chamber experiments with seed material and Rhododendron cuttings from six populations each of native Georgian, native Spanish and invasive Irish populations subjected to different temperature environments.
There were no differences in the maximum germination rate and optimum germination temperature between native and invasive origins. We found significant differences in germination velocity with the Irish seeds responding most rapidly to all germination treatments. Accordingly, in the growth experiment the invasive Irish origins had the highest relative growth rates in all environments tested.
Our results provide evidence for a genetic shift in invasive populations towards an increased investment in growth and towards a faster germination rate. Both traits would contribute to explaining this species' range expansion. The underlying evolutionary mechanisms for this shift are discussed, including the possibility of hybridisation or of an ecological release from hitherto experienced constraints in the native area.     

Are growth rates of Escherichia coli in batch cultures limited by respiration?

Batch cultures of Escherichia coli were grown in minimal media supplemented with various carbon sources which supported growth at specific growth rates from 0.2 to 1.3/h. The respiration rates of the cultures were measured continuously. With few exceptions, the specific rate of oxygen consumption was about 20 mmol of O2/h per g (dry weight), suggesting that the respiratory capacity was limited at this value. The adenosine triphosphate (ATP) required for the production of cell material from the different carbon sources was calculated on the basis of known ATP requirements in the biochemical pathways and routes of macromolecular synthesis. The calculated ATP requirements, together with the measured growth rates and growth yields on the different carbon sources, were used to calculate the rate of ATP synthesis by oxidative phosphorylation. This rate was closely related to the respiration rate. We suggest that aerobic growth of E. coli in batch cultures is limited by the rate of respiration and the concomitant rate of ATP generation through oxidative phosphorylation.     

A surplus no more? Variation in krill availability impacts reproductive rates of Antarctic baleen whales

The krill surplus hypothesis of unlimited prey resources available for Antarctic predators due to commercial whaling in the 20th century has remained largely untested since the 1970s. Rapid warming of the Western Antarctic Peninsula (WAP) over the past 50 years has resulted in decreased seasonal ice cover and a reduction of krill. The latter is being exacerbated by a commercial krill fishery in the region. Despite this, humpback whale populations have increased but may be at a threshold for growth based on these human-induced changes. Understanding how climate-mediated variation in prey availability influences humpback whale population dynamics is critical for focused management and conservation actions. Using an 8-year dataset (2013–2020), we show that inter-annual humpback whale pregnancy rates, as determined from skin-blubber biopsy samples (n = 616), are positively correlated with krill availability and fluctuations in ice cover in the previous year. Pregnancy rates showed significant inter-annual variability, between 29% and 86%. Our results indicate that krill availability is in fact limiting and affecting reproductive rates, in contrast to the krill surplus hypothesis. This suggests that this population of humpback whales may be at a threshold for population growth due to prey limitations. As a result, continued warming and increased fishing along the WAP, which continue to reduce krill stocks, will likely impact this humpback whale population and other krill predators in the region. Humpback whales are sentinel species of ecosystem health, and changes in pregnancy rates can provide quantifiable signals of the impact of environmental change at the population level. Our findings must be considered paramount in developing new and more restrictive conservation and management plans for the Antarctic marine ecosystem and minimizing the negative impacts of human activities in the region.     

Sex differences in cannabinoid pharmacology: A reflection of differences in the endocannabinoid system?

Marijuana is the most widely used illicit drug in the U.S., and marijuana use by women is on the rise. Women have been found to be more susceptible to the development of cannabinoid abuse and dependence, have more severe withdrawal symptoms, and are more likely to relapse than men. The majority of research in humans suggests that women are more likely to be affected by cannabinoids than men, with reports of enhanced and decreased performance on various tasks. In rodents, females are more sensitive than males to effects of cannabinoids on tests of antinociception, motor activity, and reinforcing efficacy. Studies on effects of cannabinoid exposure during adolescence in both humans and rodents suggest that female adolescents are more likely than male adolescents to be deleteriously affected by cannabinoids. Sex differences in response to cannabinoids appear to be due to activational and perhaps organizational effects of gonadal hormones, with estradiol identified as the hormone that contributes most to the sexually dimorphic effects of cannabinoids in adults. Many, but not all sexually dimorphic effects of exogenous cannabinoids can be attributed to a sexually dimorphic endocannabinoid system in rodents, although the same has not yet been established firmly for humans. A greater understanding of the mechanisms underlying sexually dimorphic effects of cannabinoids will facilitate development of sex-specific approaches to treat marijuana dependence and to use cannabinoid-based medications therapeutically.     

Regional differences in bacterial flora in harbour porpoises from the North Atlantic: environmental effects?

Aims:  Microbiological findings in harbour porpoises from different regions of the North Atlantic were compared. Results in animals from the North and Baltic Seas were evaluated over a period of 18 years for changes in the microbiological flora.
Methods and Results:  Microbiological investigations were performed on 1429 organ samples from the lung, liver, kidney, spleen, intestine, and mesenteric lymph nodes from harbour porpoises of the German North and Baltic Seas, Greenlandic, Icelandic and Norwegian waters. A large variety of bacteria, including potentially pathogenic bacteria like Brucella sp., Clostridium perfringens, Escherichia coli, Erysipelothrix rhusiopathiae , β-haemolytic streptococci and Staphylococcus aureus were isolated . Those bacteria were associated with bronchopneumonia, gastroenteritis, hepatitis, pyelonephritis, myocarditis and septicemia.
Conclusions:  Organs from animals originating from Greenlandic and Icelandic waters showed clearly less bacterial growth and fewer associated pathological lesions compared to animals from the German North and Baltic Seas and Norwegian waters.
Significance and Impact of the Study:  Differences in bacterial findings and associated lesions between harbour porpoises from the German North and Baltic Seas and animals from Greenlandic, Norwegian and Icelandic waters may result from higher stress due to anthropogenic activities such as chemical pollutants in the North and Baltic Seas.     

Are prostaglandins involved in the regulation of coronary blood flow? A review of the evidence

Prostaglandins (PG's) fulfil most of the criteria required for the metabolic "coupler" linking increases in myocardial activity with increases in coronary blood flow. They are synthesized by the heart and coronary vessels, profoundly modify coronary blood flow in low concentrations and are released under conditions of hypoxia and myocardial ischaemia. Studies with inhibitors of PG-synthetase however provide no firm evidence that PG's are involved in the physiological regulation of myocardial blood flow. These studies are reviewed.     

Cellular calcium and redox regulation: the mediator of vertebrate environmental sex determination?

Many reptiles and some fish determine offspring sex by environmental cues such as incubation temperature. The mechanism by which environmental signals are captured and transduced into specific sexual phenotypes has remained unexplained for over 50 years. Indeed, environmental sex determination (ESD) has been viewed as an intractable problem because sex determination is influenced by a myriad of genes that may be subject to environmental influence. Recent demonstrations of ancient, conserved epigenetic processes in the regulatory response to environmental cues suggest that the mechanisms of ESD have a previously unsuspected level of commonality, but the proximal sensor of temperature that ultimately gives rise to one sexual phenotype or the other remains unidentified. Here, we propose that in ESD species, environmental cues are sensed by the cell through highly conserved ancestral elements of calcium and redox (CaRe) status, then transduced to activate ubiquitous signal transduction pathways, or influence epigenetic processes, ultimately to drive the differential expression of sex genes. The early evolutionary origins of CaRe regulation, and its essential role in eukaryotic cell function, gives CaRe a propensity to be independently recruited for diverse roles as a ‘cellular sensor’ of environmental conditions. Our synthesis provides the first cohesive mechanistic model connecting environmental signals and sex determination pathways in vertebrates, providing direction and a framework for developing targeted experimentation.     

Chromosome segregation from cell hybrids. II. Do differences in parental cell growth rates and phase times determine direction of loss?

The hypothesis that the direction of chromosome segregation in cell hybrids is determined by the interaction of parent cell cycles, or S-phase times, predicts that the segregant parent will always be the one with the longer cycle, or the longer S phase, and that late replicating chromosomes will be more frequently lost. We have tested this hypothesis by studying cell cycle parameters of mouse, Chinese hamster, and platypus parent cells and by observing chromosome loss and replication patterns in hybrids between them. Two types of hybrids have been studied: mouse-hamster hybrids showed gradual segregation, in one or other direction, of 10-60% chromosomes, while rodent-platypus hybrids (which could be selected under conditions optimal for either parent cell) showed rapid and extreme segregation of platypus chromosomes. We found no correlation between the direction of segregation and the relative lengths of parental cycle times, or phase times, nor between sequence of replication and frequency with which segregant chromosomes are lost. We therefore conclude that the direction and extent of segregation is not directly determined by the interaction of parental cycle or phase times.     

Testing for evidence of inefficient selection in bdelloid rotifers: do sample size and habitat differences matter?

Preliminary evidence on inefficient selection has indicated that asexual (=parthenogenetic) animals suffer from a greater accumulation of deleterious mutations compared with their closest sexual sister taxa. However, previous work on bdelloid rotifers did not completely rule out the confounding effects of sample size and habitat differences. Here, we present further evidence of inefficient selection against deleterious mutations in the bdelloid rotifers in comparison with their closest clade, the monogononts, by taking account of larger samples. However, the analysis of samples from both clades co-occurring in the same location seems to contradict the hypothesis. Both groups show evidence of the accumulation of deleterious mutations in mitochondrial DNA, but further population sampling and inclusion of additional genes is needed to resolve this issue.     

Does seed mass drive the differences in relative growth rate between growth forms?

The idea that herbaceous plants have higher relative growth rates (RGRs) compared with woody plants is fundamental to many of the most influential theories in plant ecology. This difference in growth rate is thought to reflect systematic variation in physiology, allocation and leaf construction. Previous studies documenting this effect have, however, ignored differences in seed mass. As woody species often have larger seeds and RGR is negatively correlated with seed mass, it is entirely possible the lower RGRs observed in woody species is a consequence of having larger seeds rather than different growth strategies. Using a synthesis of the published literature, we explored the relationship between RGR and growth form, accounting for the effects of seed mass and study-specific effects (e.g. duration of study and pot volume), using a mixed-effects model. The model showed that herbaceous species do indeed have higher RGRs than woody species, and that the difference was independent of seed mass, thus at all seed masses, herbaceous species on average grow faster than woody ones.