An ancestral axial twist explains the contralateral forebrain and the optic chiasm in vertebrates

Among the best-known facts of the brain are the contralateral visual, auditory, sensational, and motor mappings in the forebrain. How and why did these evolve? The few theories to this question provide functional answers, such as better networks for visuomotor control. However, these theories contradict the data, as discussed here. Instead we propose that a 90-deg left-turn around the body-axis evolved in a common ancestor of all vertebrates. Compensatory migrations of the tissues during development restore body symmetry. Eyes, nostrils and forebrain compensate in the direction of the turn, whereas more caudal structures migrate in the opposite direction. As a result of these opposite migrations the forebrain becomes crossed and inverted with respect to the rest of the nervous system. We show that these compensatory migratory movements can indeed be observed in the zebrafish (Danio rerio) and the chick (Gallus gallus). With a model we show how the axial twist hypothesis predicts that an optic chiasm should develop on the ventral side of the brain, whereas the olfactory tract should be uncrossed. In addition, the hypothesis explains the decussation of the trochlear nerve, why olfaction is non-crossed, why the cerebellar hemispheres represent the ipsilateral bodyside, why in sharks the forebrain halves each represent the ipsilateral eye, why the heart and other inner organs are asymmetric in the body. Due to the poor fossil record, the possible evolutionary scenarios remain speculative. Molecular evidence does support the hypothesis. The findings may throw new insight on the problematic structure of the forebrain.Comment: 13 pages, 6 figures. A small correction is made (May 2014): see footnote

Veilig voedsel voor veel monden

Onze verre voorouders konden hun eten gewoon uit de natuur halen. Natuur genoeg voor zo'n klein clubje mensen. Maar de bijna zeven miljard monden van nu kunje alleen voeden met de hulp van intensieve landbouw. 'Daarmee is de kennis van de biologie en van biologische bestrijding van levensbelang', zeggen emeritus hoogleraren Jan Osse en Louis Schoonhoven van de Wageningen Universitei

Diversification of prey capture techniques among the piscivores in Lake Tana's (Ethiopia) Labeobarbus species flock (Cyprinidae)

Lake Tana harbours the only known intact species flock of large cyprinid fishes (15 Labeobarbus spp.). One of the most curious aspects of this species flock is the large number (8) of piscivorous species. Cyprinids are not well designed for piscivory (i.e. small slit-shaped pharyngeal cavity, lack of teeth in the oral jaws, lack of a stomach), which raises the question how well adapted these labeobarbs actually are to function as piscivores? In this study we analyse the kinematics of prey capture (by varied combinations of suction, swimming and jaw protrusion) among Lake Tana's piscivorous labeobarbs. Suction feeding kinematics were similar to values reported for other piscivorous fish species. A detailed analysis of several Labeobarbus species displayed distinct types of techniques (overswimming, velocity/volume suction with jaw protrusion) suited to capture elusive prey in different macro-habitats, Lake Tana's Labeobarbus species evolved a wide range of piscivorous predation techniques, a unique scenario for cyprinid fishes

Delirium after Cardiac Surgery in Older Patients : Predictors of occurrence and outcome

As early as in Hippocrates’ medical writings, clinical pictures of patients experiencing delirium were described . The syndrome we currently refer to as delirium was originally based on two distinct syndromes. A syndrome called Phrenitis, in which patients showed cognitive disturbances, exited and restless behaviour, with disruption of sleep, and a syndrome called Lethargus, in which patients were somnolent, apathetic, listless and showed slow mentation. Although it was known that Phrenitis could change into Lethargus, and vice versa, it was not until the late eighteenth century that both terms were displaced by the single term delirium. There is some uncertainty whether the word ‘delirium’ is derived from the Greek word ληρος, meaning empty drivel , or from the Latin word for disturbance of mind, deliratio . Even in ancient times it was known that the emergence of a delirium was a bad prognostic sign and often a herald of death, but the pathophysiology remained obscure. Based on meticulous observations of patients, the German psychiatrist Bonhoeffer reported in 1910 that the presence of the symptom clouding of consciousness could discriminate organic-psychiatric disorders from functional or endogenous psychiatric disorders . Furthermore, he postulated that toxic substances originating from disease processes in the body or brain might cause delirium. A theory that is remarkably similar to the present-day inflammatory delirium theory, in which cytokines produced by glia cells induce delirium . Engel and Romano in 1959 further elaborated on the delirium concept by describing the association between a reduced level of consciousness and the degree of slowing of the electro-encephalogram (EEG) . Combined with the finding that slowing of the EEG was associated with derangements of cerebral metabolism, this provided additional evidence that delirium should be regarded as a syndrome of cerebral insufficiency. Currently, delirium is the most frequently occurring organic-psychiatric syndrome in the general hospital. The incidence of delirium in the general hospital ranges from 5 to 32% , but in specific populations, such as older patients (aged 65 years or more) or patients in the intensive care unit (ICU), the incidence of delirium can be much higher

THE EILENBERG–MOORE SPECTRAL SEQUENCE IN K-THEORY

AbstractWe construct the Eilenberg–Moore spectral sequence for some generalized cohomology theories, along the lines of Smith and Hodgkin. We prove its multiplicativity and give some sufficient conditions for its convergence to the desired target. As applications, we compute the K-theory of various spaces associated to p-compact groups

Mental health and quality of life at a student hall of residence at the Universidade de Brasília, Brazil

O objetivo do presente estudo foi mapear as condições psicossociais e a qualidade de vida de universitários da moradia estudantil da Universidade de Brasília. Oitenta e sete voluntários com média de idade de vinte e dois anos participaram da pesquisa. Foram utilizados questionários auto-aplicáveis sobre a situação socio-demográfica, eventos de vida, uso de álcool e drogas e comportamento suicida. Estudantes dependents de recursos institucionais, em fases iniciais de curso, a maioria vinda de outros estados, apresentaram pródromos que indicaram ansiedade, depressão e dificuldades em relação à ajuda. Comportamentos de risco apareceram como forma de solução de problemas relacionados à adaptação ao novo contexto. Os programas assistenciais existentes na universidade não conseguem cobrir toda a complexa demanda. Sugerem-se ações emergenciais para que os programas existentes sejam ampliados e a criação de novos serviços para garantir a permanência do universitário até o final do curso com melhor qualidade de vida.The purpose of this study was to map the psychological and social conditions and the quality-of-life of young students living in halls of residence at the Universidade de Brasília. Eighty-seven students with an average age of twenty-two volunteered to take part in the research. Self-applied questionnaires were used dealing with issues relating to their socio-demographic situation, life events, consumption of drugs or alcohol and suicidal behavior. These students, who had just begun their courses and were dependent on money allocated by the university, and came from other states, presented prodromal symptoms such as anxiety, depression and difficulties in accepting/seeking help. Problem behavior presented as a solution to issues related to adaptation to the new environment. The university's assistance programs are unable to meet the complex demand. The current programs could be enhanced, and other services created, in order to guarantee improvement in the quality of life of students through the end of their courses

Indicators of petroleum product exposure in benthic cold-water marine invertebrates

The ubiquity of petroleum in society has led to widespread pollution of the marine environment resulting in a need to identify suitable biomarkers. The aim of this study was two-fold: (1) To measure variables that influence baseline biomarker activity and (2) to determine their response to the water-accommodating fraction of used engine lubricating oil. The biomarkers glutathione peroxidase (GPx) and ethoxyresorufin-O-deethylase (EROD) were studied across three stages of the breeding cycle within the reproductive and digestive tissues of the common sea star, the orange-footed sea cucumber, the daisy brittle star, and the green sea urchin. Overall, sea stars were identified as the most promising cold-water biomonitors of oil contamination among the species studied, and GPx was found to be the most suitable biomarker due to its widespread activity, lack of seasonal baseline variation, and the simple separation of sexes during analyses. In comparison, the baseline activity of EROD was influenced by both season and sex