Hemispheric asymmetry in ocean change and the productivity of ecosystem sentinels.

Climate change and other human activities are causing profound effects on marine ecosystem productivity. We show that the breeding success of seabirds is tracking hemispheric differences in ocean warming and human impacts, with the strongest effects on fish-eating, surface-foraging species in the north. Hemispheric asymmetry suggests the need for ocean management at hemispheric scales. For the north, tactical, climate-based recovery plans for forage fish resources are needed to recover seabird breeding productivity. In the south, lower-magnitude change in seabird productivity presents opportunities for strategic management approaches such as large marine protected areas to sustain food webs and maintain predator productivity. Global monitoring of seabird productivity enables the detection of ecosystem change in remote regions and contributes to our understanding of marine climate impacts on ecosystems.

Physiology and development of the M and S molecular forms of Anopheles gambiae in Burkina Faso (West Africa).

In West Africa, M and S molecular forms of Anopheles gambiae sensu stricto (Diptera: Culicidae) Giles, frequently occur together, although with different population bionomics. The S form typically breeds in rain-dependant water collections and is present during the rainy season only whereas the M form can thrive all year long in areas with permanent breeding opportunities. In the present study, we explored physiological and developmental trade-offs at play in laboratory colonies and field populations of the M and S forms that originated from an area of sympatry in Burkina Faso, where M and S larvae exhibit such habitat segregation. In the laboratory, larvae of the M form developed slower than the S form (mean values 9.51 and 8.85 days, respectively, Wilcoxon's test, P < 0.001). Although wing length and dry weight at emergence showed large variations, M females were on average 8% heavier than S females of similar wing length. Higher nutritional reserves (proteins and lipids) in teneral adults explained part of this weight difference, reflecting a better ability of the M form to garner resources at the larval stage. Furthermore, a higher rate of ovarian maturation was observed in the M form after a single bloodmeal. The relevance of these findings for parasite transmission is discussed.

Rapid evolution of Wolbachia density in insecticide resistant Culex pipiens.

The maternally inherited symbiotic Wolbachia have been previously shown to have much greater densities in insecticide-resistant Culex pipiens mosquitoes than in insecticide-susceptible individuals. These high densities were shown to be at least partially responsible for the costs related to insecticide resistance in this species. We report here the rapid evolution, on the order of 50 generations, of bacterial densities both in laboratory and field populations. Along with other recently published studies, this report shows that Wolbachia-host interactions are very dynamic.

Resource depletion in Aedes aegypti mosquitoes infected by the microsporidia Vavraia culicis.

SUMMARYParasitic infection is often associated with changes in host life-history traits, such as host development. Many of these life-history changes are ultimately thought to be the result of a depletion or reallocation of the host's resources driven either by the host (to minimize the effects of infection) or by the parasite (to maximize its growth rate). In this paper we investigate the energetic budget of Aedes aegypti mosquito larvae infected by Vavraia culicis, a microsporidian parasite that transmits horizontally between larvae, and which has been previously shown to reduce the probability of pupation of its host. Our results show that infected larvae have significantly less lipids, sugars and glycogen than uninfected larvae. These differences in resources were not due to differences in larval energy intake (feeding rate) or expenditure (metabolic rate). We conclude that the lower energetic resources of infected mosquitoes are the result of the high metabolic demands that microsporidian parasites impose on their hosts. Given the fitness advantages for the parasite of maintaining the host in a larval stage, we discuss whether resource depletion may also be a parasite mechanism to prevent the pupation of the larvae and thus maximize its own transmission.

Asexual reproduction: genetics and evolutionary aspects.

Reproduction is essential to all organisms if they are to contribute to the next generation. There are various means and ways of achieving this goal. This review focuses on the role of asexual reproduction for eukaryotic organisms and how its integration in a life cycle can influence their population genetics and evolution. An important question for evolutionary biologists as to why some organisms reproduce sexually, as opposed to asexually, is addressed. We also discuss the economic and medical importance of asexual organisms.

Proteome of Aedes aegypti larvae in response to infection by the intracellular parasite Vavraia culicis.

We report on the modification of the Aedes aegypti larval proteome following infection by the microsporidian parasite Vavraia culicis. Mosquito larvae were sampled at 5 and 15 days of age to compare the effects of infection when the parasite was in two different developmental stages. Modifications of the host proteome due to the stress of infection were distinguished from those of a more general nature by treatments involving hypoxia. We found that the major reaction to stress was the suppression of particular protein spots. Older (15 days) larvae reacted more strongly to infection by V. culicis (46% of the total number of spots affected; 17% for 5 days larvae), while the strongest reaction of younger (5 days) larvae was to hypoxia for pH range 5-8 and to combined effects of infection and hypoxia for pH range 3-6. MALDI-TOF results indicate that proteins induced or suppressed by infection are involved directly or indirectly in defense against microorganisms. Finally, our MALDI-TOF results suggest that A. aegypti larvae try to control or clear V. culicis infection and also that V. culicis probably impairs the immune defense of this host via arginases-NOS competition.

Sex-specific reaction norms to intraspecific larval competition in the mosquito Aedes aegypti.

As the relationship between a given life-history trait and fitness is not necessarily the same for the two sexes, an 'intersexual ontogenetic conflict' may arise. We analysed the phenotypic reaction to intraspecific larval competition of the mosquito, Aedes aegypti, asking: (i) Do both sexes pay the cost of competition with the same life-history traits and are they equal competitors? (ii) Is there a specific cost of competition beyond sharing food resources? We found that competition incurs a specific cost that was expressed differently by the two sexes. Indeed, each sex maintained the more important life-history trait(s) for their fitness (developmental time for males and body weight and size for females) at the expense of other traits, thus minimizing the effects of competition on their fitness. The competition exerted by females was estimated as being more intense, probably linked with the greater importance of body size for their fitness.

In vitro growth of Leishmania amazonensis promastigotes resistant to pentamidine is dependent on interactions among strains.

The in vitro growth of promastigote cells of Leishmania amazonensis was found to strongly depend on interactions among strains that differed in their pentamidine resistance. In particular, the growth of resistant strains was reduced when they shared the same environment with a less-resistant strain.

Effects of density and larval competition on selected life history traits of Culex pipiens quinquefasciatus (Diptera: Culicidae).

The effects of larval densities of one to four individuals in standard Drosophila-vials (diameter 25 by 95 mm) on the age at pupation, starved dry weight, and wing length of Culex pipiens quinquefasciatus Say were studied. This approach required relatively few larvae per replicate and included a control treatment, where individual larvae developed in the absence of competition. This design also tested for competitive interactions between male and female larvae. Mosquitoes pupated later, and emerged with lighter starved dry adult weight and shorter wings as larval density increased. The size of adult female mosquitoes, particularly their starved dry weight, was sensitive to larval density and also was influenced by the presence or absence of competition with another female larva. In contrast, the life history traits of males did not vary as a function of competition with female larva. Female larvae were also more likely to die in the highest density treatment. This design confirmed previous results and offered a potentially useful experimental approach to investigate the effects of density-dependent competition among mosquito larvae.

Host life history responses to parasitism.

Parasites and their infections can adversely effect a host's growth, reproduction and survival. These effects are often not immediate, but increase with time since infection. A general prediction from evolutionary biology is that hosts suffering from this type of infection should preferentially allocate resources towards reproduction, even if this is at the expense of their growth and survival. This review illustrates this argument with several empirical studies showing hosts behaving in this manner. These studies indicate that one way for hosts to reduce the costs of parasitism is by altering their life history traits to bring forward their schedule of reproduction.

An algorithmic approach to evaluation of the flatfoot. Avoidance of pitfalls.

The authors have attempted to lead the reader through a comprehensive and systematic diagnosis of the patient with the flatfoot. The authors followed the familiar SOAP format. Within each of the major steps (subjective findings, objective findings, assessment, and plan) a systematic algorithm is proposed. These are designed with the objective of comprehensively evaluating the patient. This should dissuade the reader from myopically approaching the flatfoot, and potentially missing comorbid or etiologic systemic disease. A brief introduction to a systematic treatment philosophy is also presented. Unfortunately exhaustive discussion of each of the steps would require a separate article. The authors hope that the controversies highlighted will stimulate further research into this subject. It is also hoped that anyone approaching the patient with flexible flatfoot would avoid some of the dogmatic philosophies that have plagued this subject. Until well-developed scientific research answering the basic questions is done, all currently available approaches are based on opinion and personal bias.

Coevolutionary interactions between host life histories and parasite life cycles.

Several recent studies have discussed the interaction of host life-history traits and parasite life cycles. It has been observed that the life-history of a host often changes after infection by a parasite. In some cases, changes of host life-history traits reduce the costs of parasitism and can be interpreted as a form of resistance against the parasite. In other cases, changes of host life-history traits increase the parasite's transmission and can be interpreted as manipulation by the parasite. Alternatively, changes of host's life-history traits can also induce responses in the parasite's life cycle traits. After a brief review of recent studies, we treat in more detail the interaction between the microsporidian parasite Edhazardia aedis and its host, the mosquito Aedes aegypti. We consider the interactions between the host's life-history and parasite's life cycle that help shape the evolutionary ecology of their relationship. In particular, these interactions determine whether the parasite is benign and transmits vertically or is virulent and transmits horizontally.

Evaluation of the child with ligamentous laxity.

Many opportunities for participation in the care of children with ligamentous laxity have been described in this article. The podiatric physician must determine his or her contribution based on knowledge, experience, and interest. Each podiatric physician is not necessarily expected to be familiar with all of the diseases and treatments described here. Novice podiatrists should be mandated to recognize only the presence of ligamentous laxity and be familiar with an appropriate referral pattern. In addition to the previously listed podiatric concerns, Hobson has described some specific concerns in even the most basic podiatric treatment. He recommends the use of skin adherents to avoid wrinkling and tearing the skin of individuals with Ehlers-Danlos syndrome. He also reiterates research that has determined a resistance to local anesthetics in these individuals. He further provides some detail for the manufacture of appropriate orthoses. Continuing education may be obtained through a variety of sources. These may include not only traditional podiatric courses and conferences, but also similar venues offered by clinicians in other specialties. Also, courses and conferences held by organizations with a special interest in these unusual disorders can be educational and rewarding. The author has found interactions with this patient population rewarding. The patients and their families are often exceptionally knowledgeable regarding their illness because most have experienced many years with unsatisfactory medical help and delayed or incorrect diagnoses. Most of these families are also extraordinarily grateful for the concern and interest expressed by the clinician. They are particularly impressed when the health care professional has at least a cursory knowledge of their unusual disorder. As a member of the Ehlers-Danlos National Foundation Medical Advisors Panel, the author has contact with world-renowned geneticists, rheumatologists, and other specialists. The leader of the organization has pointed out that patients have found that podiatric clinics provided during the national meetings are often one of the most appreciated aspects of those meetings. He stated that although podiatrists may not cure the disease, small improvements in the everyday lives of these patients add up to a significant contribution. The author hopes that this article will stimulate further interests in the care and understanding of individuals with ligamentous laxity. It is further hoped that experience with these individuals will translate to the broader population who experience milder disorders of hypermobility.

Virulence, parasite mode of transmission, and host fluctuating asymmetry.

Horizontally transmitted parasites are broadly predicted to be more virulent, or costly to host fitness, than those with vertical transmission. This is mainly because vertical transmission, from host parent to offspring, explicitly links the reproductive interests of both parties. Underlying this prediction is a general assumption that parasite transmission success is positively correlated with its virulence. We report results where infection of larval yellow fever mosquitoes Aedes aegypti with the microsporidian Edhazardia aedis was experimentally manipulated. The parasite's complex life cycle allowed comparisons between estimates of horizontal and vertical transmission on host fitness. Our measure of virulence was the fluctuating asymmetry (FA) of adult female wings. Hosts harbouring spores showed higher FAs than controls. Horizontally transmitting spores were associated with higher FAs than vertically transmitting spores. Furthermore, within hosts FA correlated positively with the number of horizontally transmitting spores, while no relation was seen with the number of vertically transmitting spores. A developmental mechanism uncoupling the relationship between vertical transmission and virulence is proposed.

Nonskid socks.

For children with normal anatomy, nonskid socks may be safe for indoor wear. However, they lack some protection capacity, and are not biomechanically helpful. Little scientific data exist to guide physicians on what children should wear on their feet. Dogma and prejudice may taint the advice physicians give. Perhaps this type of project will spur further investigation.

Avascular necrosis of the talus in a toddler.

Avascular necrosis (AVN) of the talus is a controversial complication of trauma in children. A case of AVN is presented with a 2-year follow-up. More aggressive initial treatment may be indicated to avoid this complication. Close follow-up and suspicion are recommended.

Taping of foot and ankle for Korean karate.

In the practice of Korean karate, the foot is often used as a weapon in self defense. Injuries to the foot are common. Analysis of patterns to these injuries and requirements of the sport led to the development of a strapping technique for protecting the foot from the most common injuries.