Is hatching asynchrony beneficial for the brood?

Many hypotheses have been proposed to explain why female birdsstart to incubate before clutch completion (IBCC). Some of thosesuggest that the resulting hatching asynchrony (HA) is adaptivebecause it increases the size hierarchy among offspring andin turn reduces nestling competition and energy demands duringthe peak feeding period. Others argue that IBCC is a good strategyin unpredictable environments. When food conditions deteriorate,the large size hierarchy quickly results in the death of thelast hatched nestlings, allowing the remaining ones to surviveand fledge in better condition. In comparison, under favorableconditions, all nestlings can fledge independent of hatchingorder. To test these hypotheses, we performed a brood size manipulationexperiment (as a simulation of good and bad years) in collaredflycatchers Ficedula albicollis and examined the effect of sizehierarchy on offspring and brood performance. We found thatchicks with an initial size disadvantage experienced reducedbody mass growth and had shorter feathers at fledging in bothreduced and enlarged broods. In enlarged broods, they also fledgedwith a smaller skeletal size. Although broods on average orparents could possibly still benefit from HA when food is scarce,this was not seen in the current study. Parental survival wasnot related to the size hierarchy in the broods, and the averagebody mass growth of the nestlings was slower in broods witha high initial size variance. We therefore conclude that HAand the resulting size hierarchy are probably detrimental forthe growth of nestlings in both good and bad years, at leastin species where nestling mortality does not occur early inlife.     

Bright light therapy for winter depression--is phase advancing beneficial?

Bright light is the recommended treatment for winter seasonal affective disorder (SAD). Previously we showed that the antidepressant effect of morning (but not evening) light was greater than placebo after 3 weeks of treatment. Here, we determined if the magnitude and direction of circadian rhythm phase shifts produced by the bright light in the previous study were related to the antidepressant effects. Twenty-six SAD patients from the original sample of 96 had their rectal temperature continuously monitored while they participated in a placebo-controlled parallel design conducted over six winters. After a baseline week, there were three treatments for 4 weeks-morning light, evening light, or morning placebo. Bright light was produced by light boxes (approximately 6000 lux). Placebos were sham negative ion generators. All treatments were 1.5 h in duration. Depression ratings were made weekly by blind raters. Circadian phase shifts were determined from changes in the timing of the core body temperature minimum (Tmin). Morning light advanced and evening light delayed the Tmin by about 1 h. The placebo treatment did not alter circadian phase. As the sleep schedule was held constant, morning light increased and evening light decreased the Tmin to wake interval, or phase angle between circadian rhythms and sleep. Phase advance shifts and increases in the phase angle were only weakly associated with antidepressant response. However, there was an inverted U-shaped function showing that regardless of treatment assignment the greatest antidepressant effects occurred when the phase angle was about 3h, and that patients who moved closer to this phase angle benefited more than those who moved farther from it. However 46% of our sample had a phase angle within 30 min of this 3 h interval at baseline. So it does not appear that an abnormal phase angle can entirely account for the etiology of SAD. A majority (75%) of the responders by strict joint criteria had a phase angle within this range after treatment, so it appears that obtaining the ideal phase relationship may account for some, but not all of the antidepressant response. In any case, regardless of the mechanism for the antidepressant effect of morning light, it can be enhanced when patients sleep at the ideal circadian phase and reduced when they sleep at a more abnormal circadian phase.     

Is elongation-induced leaf emergence beneficial for submerged Rumex species?

Background and Aims

Plant species from various taxa ‘escape’ from low oxygen conditions associated with submergence by a suite of traits collectively called the low oxygen escape syndrome (LOES). The expression of these traits is associated with costs and benefits. Thus far, remarkably few studies have dealt with the expected benefits of the LOES.

Methods

Young plants were fully submerged at initial depths of 450 mm (deep) or 150–240 mm (shallow). Rumex palustris leaf tips emerged from the shallow flooding within a few days, whereas a slight lowering of shallow flooding was required to expose R. acetosa leaf tips to the atmosphere. Shoot biomass and petiole porosity were measured for all species, and treatments and data from the deep and shallow submergence treatments were compared with non-flooded controls.

Key Results

R. palustris is characterized by submergence-induced enhanced petiole elongation. R. acetosa lacked this growth response. Upon leaf tip emergence, R. palustris increased its biomass, whereas R. acetosa did not. Furthermore, petiole porosity in R. palustris was twice as high as in R. acetosa.

Conclusions

Leaf emergence restores gas exchange between roots and the atmosphere in R. palustris. This occurs to a much lesser extent in R. acetosa and is attributable to its lower petiole porosity and therefore limited internal gas transport. Leaf emergence resulting from fast petiole elongation appears to benefit biomass accumulation if these plants contain sufficient aerenchyma in petioles and roots to facilitate internal gas exchange.Key words: Submergence, emergence, enhanced shoot elongation, porosity, aerenchyma, Rumex, cost–benefit analysis, phenotypic plasticity     

Is fever beneficial?

Fever, the regulation of body temperature at an elevated level, is a common response to infection throughout the vertebrates, as well as in many species of invertebrate animals. It is probable that fever evolved as an adaptive response to infection hundreds of millions of years ago. Many components of the nonspecific and specific host response to infection are enhanced by small elevations in temperature. Perhaps more important, studies of bacterial- and viral-infected animals have shown that, in general, moderate fevers decrease morbidity and increase survival rate.     

Visual cortex: suppression by depression?

The response of a neuron in the visual cortex to an oriented light bar is strongly reduced by concurrent presentation of a stimulus with a different orientation. New data suggest this 'cross-orientation suppression' is caused, not by intracortical inhibition, but by rapid depression of thalamocortical synapses.     

A silver bullet for the treatment of depression?

The search for a rapid-acting antidepressant has been a subject of intense research interest for several decades. The article by Lucas and colleagues in this issue of Neuron provides compelling evidence from preclinical animal models that drugs acting at the serotonin 5-HT(4) receptor could finally achieve this goal. However, caution is warranted, as results from animal studies are not always predictive of therapeutic actions in humans.     

Is dietary restriction beneficial for human health, such as for immune function?

PURPOSE OF REVIEW: The impact of dietary restriction on physiologic function in humans is now beginning to be examined. The clinical trials are fueled by decades of animal experiments showing that dietary restriction delays the aging process and decreases the incidence of many age-associated diseases. The critical issue addressed in this article is whether or not dietary restriction long term is feasible or beneficial in humans. RECENT FINDINGS: Short-term dietary restriction in humans does appear to have beneficial effects at lowering metabolism, especially when examining carbohydrates and weight loss. Dietary restriction long term does, however, have detrimental psychological effects in humans, making its feasibility questionable. Even short-term dietary restriction can negatively impact physical activity and potentially some aspects of immunity. The best avenue for humans to benefit from dietary restriction would be for pharmacological or bioactive food ingredient mimetics to be developed which would be more applicable for long-term use. SUMMARY: Dietary restriction per se is unlikely to emerge as a feasible long-term strategy to improve human health. Developing dietary restriction mimetics targeting energy metabolism may prove beneficial, not only in aging, but also in diabetes and obesity.     

Translational proteomics: what can you do for true patients?

Matching the right medical strategy to the right patient is the key for modern clinical oncology. To this aim, we have many delicate drugs designed to target in elegant ways critical proteins identified in cancer cells. However, clinical oncologists and multidisciplinary groups devoted to treating patients in an integrative fashion have histology and an TNM staging system as the most relevant biomarkers to decide therapeutic approaches for our patients. In addition, the most used drugs are classical chemotherapeutic compounds such as cisplatin, epirrubicin, irinotecan, oxaliplatin, and so on. Thus, new targeted therapies, surgery, radiotherapy, and chemotherapy will live together causing a duality for the immediate future. We will try to delineate unmet needs for clinical oncologists that would add value for cancer proteomics in terms of true patients.     

Can varying inbreeding depression select for intermediary selfing rates?

We study the evolution of the self-fertilization of an annual hermaphroditic plant under varying inbreeding depression. While classical population genetic models treat inbreeding depression as a constant parameter, recent empirical research has shown that changing environmental conditions can make inbreeding depression vary. Here, we create a simple phenotypic model, assuming variable inbreeding depression. We investigate how different types of variability (spatial, temporal, and spatiotemporal variability) affect the evolution of selfing rates in three models. Two main results, which differ from the classical predictions, emerge from this study. First, we find that fluctuating environments, which influence the magnitude of inbreeding depression, are able to select for evolutionarily stable intermediary selfing rates. Second, we show that spatiotemporal variation of inbreeding depression can lead to the development and the maintenance of polymorphic selfing rates within a population.     

Metabolic rate depression in a marine pulmonate snail: pre-adaptation for a terrestrial existence?

Summary Terrestrial and freshwater pulmonate snails exhibit a marked depression of aerobic metabolism during estivation. This is an adaptation for existence in periodically harsh environments and, though marine gastropods may undergo anaerobic metabolism, they have not been shown to adaptively depress aerobic metabolic rate. We compared the metabolic response to progressive aerial exposure of two intertidal gastropod limpets, a prosobranch and a pulmonate. The prosobranch Patella granularis maintained a constant heart rate until shortly before death. In contrast, the pulmonate Siphonaria oculus underwent facultative depression of heart rate, accompanied by a decline in oxygen consumption. Both heart rate and oxygen consumption returned to normal levels on reimmersion in water. Metabolic rate depression is energy conserving, and may account for the ability of S. oculus to extend higher up the shore than P. granularis, into areas where food availability is low. S. oculus is a primitive, marine pulmonate, periodically subject to harsh conditions, and its capacity for metabolic rate depression may represent a pre-adaptation for life on land.     

"Broad spectrum" antidepressants: is more better for the treatment of depression?

The majority of antidepressants in current use selectively inhibit the reuptake of serotonin and/or norepinephrine. "Broad spectrum" antidepressants are compounds that inhibit the reuptake of norepinephrine, serotonin and dopamine, the three biogenic amines most closely linked to depression. The pharmacological profile of one such compound has recently been described (European Journal of Pharmacology, 461 (2003) 99). DOV 21,947, an azabicyclo[3.1.0]hexane, potently inhibits norepinephrine, serotonin and dopamine reuptake by the corresponding human transporter proteins. DOV 21,947 is orally active in the forced swim and tail suspension tests, preclinical procedures that are highly predictive of antidepressant action in patients. A closely related compound, DOV 216,303 is safe and well-tolerated in Phase I studies. The plasma concentrations of DOV 216,303 following both single and multiple doses appear sufficient to inhibit norepinephrine, serotonin, and dopamine reuptake. Based on the pivotal role proposed for dopamine in depression, it has been hypothesized that a broad spectrum antidepressant will produce a more rapid onset and/or higher efficacy than agents inhibiting the reuptake of serotonin and/or norepinephrine.     

Tumor-infiltrating lymphocytes: apparently good for melanoma patients. But why?

Tumor-infiltrating T lymphocytes (TILs) are observed in a number of human primary or metastatic tumors. Recently, gene expression profiling experiments suggested that the presence of T cells in metastatic melanomas before vaccinating the patients with tumor antigens could be a biomarker for clinical benefit from the vaccines. In this context, we review results pertaining to TILs in human melanomas, their prognostic value, and some possible reasons why their presence could help in selecting melanoma patients for vaccination against tumor-specific antigens.     

Why homocysteine-lowering therapy does not have beneficial effects on patients with cardiovascular disease?

Homocysteine is a sulfur-containing amino acid produced during the metabolism of methionine and elevated plasma levels of homocysteine have been linked to an increased risk of atherosclerosis and cardiovascular ischemic events by numerous authors. Several mechanisms by which elevated homocysteine impairs vascular function have been proposed including impairment of endothelial function and at least some of those mechanisms are induced via homocysteine-associated DNA hypomethylation. Oral administration of folic acid and B vitamins, required for remethylation of homocysteine to methionine, decreased plasma total homocysteine levels but clinical trials using folic acid and B vitamins did not confirm that the decreased plasma levels of homocysteine through diet or drugs may be paralleled by a reduction in cardiovascular risk. In our view a plausible explanation for the discordance between the epidemiologic studies and the results of the clinical trials may be related to the homocysteine-associated global DNA hypomethylation which cannot easily be reversed by homocysteine-lowering therapy.