Foraging flight distances as a measure of parental effort in blue tits Parus caeruleus differ with environmental conditions

Life-history theory predicts that parental effort in nestling provisioning is optimised in relation to the quality of individuals and/or their habitat. We studied the investment of breeding pairs of blue tits Parus caeruleus for their reproduction during three breeding seasons in deciduous (high quality) vs. mixed (low quality) habitats in order to quantify to what extent habitat quality affects parental effort. Parental effort (costs) was related to their feeding rates and flight distances during foraging. In the deciduous habitat flight distances between nest and foraging patch were shorter than in the mixed habitat (22 m and 40 m, respectively), but the feeding rates did not differ between the habitats. The total flight distance per breeding pair from the first day after hatching until the 17th day of the nestling period was about half of the distance observed in the mixed habitat (375 km and 674 km, respectively). As the quality of fledglings did not differ between habitats, the higher number of fledglings per brood reflects better rewards per foraging trip in the deciduous than in the mixed habitat. Considering the parental foraging effort (costs) and, the quality and number of offspring (benefits), the benefit-cost-ratio was 2–3 times higher in the deciduous than in the mixed woodland.     

Information-theoretical entropy as a measure of sequence variability.

We propose the use of the information-theoretical entrophy, S = -sigman pi log2 pi, as a measure of variability at a given position in a set of aligned sequences. pi stands for the fraction of times the i-th type appears at a position. For protein sequences, the sum has up to 20 terms, for nucleotide sequences, up to 4 terms, and for codon sequences, up to 61 terms. We compare S and Vs, a related measure, in detail with Vk, the traditional measure of immunoglobulin sequence variability, both in the abstract and as applied to the immunoglobulins. We conclude that S has desirable mathematical properties that Vk lacks and has intuitive and statistical meanings that accord well with the notion of variability. We find that Vk and the S-based measures are highly correlated for the immunoglobulins. We show by analysis of sequence data and by means of a mathematical model that this correlation is due to a strong tendency for the frequency of occurrence of amino acid types at a given position to be log-linear. It is not known whether the immunoglobulins are typical or atypical of protein families in this regard, nor is the origin of the observed rank-frequency distribution obvious, although we discuss several possible etiologies.     

Management of pressure sores in a specialty center. A reappraisal.

We report a study on the surgical management of 145 pressure sores in 115 patients treated in a spinal cord injury center. There is a definite trend toward better education of these patients, who do not develop their first pressure sores until years following the injury. When the patient comes in for an ulcer, he is usually healthy and the ulcer is small and clean. In such instances the ulcer can be excised and closed, preferably with a myocutaneous flap, and the patient can usually begin sitting by the 21st post-operative day. In the ideal setting he may be discharged to his home on a custom-fitted (for pressure) cushion within 4 to 5 weeks, without increasing the risk of recurrence. Prophylaxis for the future is, probably, the most essential part of the treatment.     

Parental consanguinity as a cause for increased incidence of births defects in a study of 238,942 consecutive births.

The risk for birth defects in the offspring of first-cousin matings has been estimated to increase sharply compared to non consanguineous marriages. As a general decline in the frequency of consanguineous marriages was observed in this century, one wonders whether consanguinity is still a factor in the appearance of birth defects in developed countries. Based on our registry of congenital anomalies we tried to answer to this question. In the population studied in North-Eastern France a consanguineous mating was known in 1.21% of the cases with congenital anomalies, vs. 0.27% in controls, (p < 0.001). The frequency of the malformations recorded paralleled the degree of consanguinity: out of 89 malformed children, 51 were seen in first-cousins mating (10.3 times more frequent than in offspring of non consanguineous couples), 17 in second-cousins marriages and 18 in more distant relatives mating. Three were uncle-niece marriage. Excluding known mendelian conditions these numbers were 73, 36, 17 and 17 respectively and the corresponding relative risk were 3.68, 3.01, 3.41 and 4.89 respectively. Therefore there is a negative dose-response effect between level of inbreeding and risk of congenital malformations. Consanguineous mothers were more often pregnant than non consanguineous mothers (p < 0.01) and they had more stillbirths than non consanguineous mothers. These results show that consanguinity is still a factor of birth defects and they must be taken into account for genetic counseling of inbred marriages, in developed countries.     

Migration as a determinant of marriage pattern: preliminary report on consanguinity among Afghans

Two sample populations, one refugee and one resident, were studied. The frequencies of consanguineous marriages came out to be 49.8%and 55.4%, respectively, for the refugees and the residents. Caste endogamy was dominant both in the residents and the refugees. The mean coefficient of inbreeding was calculated to be 0.0303 for the refugee population and 0.0332 for the resident population samples. First cousin marriage was the dominant type of marriage in both samples; father's brother's daughter (FBD) marriage was more frequent among the refugees while mother's brother's daughter(MBD) marriage was more frequent among the residents. Education has no decreasing effect on the incidence of consanguineous marriages. A significant difference in the pattern of marriages in the refugees is observed after the Saur Revolution of 1979.     

Using saturation-recovery EPR to measure distances in proteins: applications to photosystem II.

The stable tyrosine radical YD. (tyrosine 160 in the D2 polypeptide) in photosystem II (PSII) exhibits nonexponential electron spin-lattice relaxation transients at low temperature. As previously reported, the tetranuclear Mn complex in PSII significantly enhances the spin-lattice relaxation of YD.. However, in Mn-depleted PSII membranes, the spin-lattice relaxation transients of YD. are also nonexponential, and progressive power saturation (P 1/2) experiments show that it does not behave like an isolated tyrosine radical. A model is developed to treat the interaction of two paramagnets in a rigid lattice at a fixed distance apart but with a random orientation in a magnetic field. This model describes the spin-lattice relaxation of a radical in proximity to another paramagnetic site in terms of three relaxation rate constants: the "intrinsic" relaxation rate, the relaxation rate due to scalar exchange, and the relaxation rate due to dipole-dipole interactions. The intrinsic and the scalar exchange relaxation rates are isotropic and together contribute a single rate constant to the spin-lattice relaxation transients. However, the dipolar relaxation rate is orientation dependent. Each orientation contributes a different dipolar relaxation rate constant to the net spin-lattice relaxation rate constant. The result is a superposition of single-exponential recoveries, each with a different net rate constant, causing the observed saturation-recovery transients to be non-(single)-exponential. Saturation-recovery relaxation transients of YD. are compared with those of a model tyrosine radical, generated by UV photolysis of L-tyrosine in a borate glass. From this comparison, we conclude that scalar exchange does not make a significant contribution to the spin-lattice relaxation of YD. in Mn-depleted PSII. We account for the nonexponential relaxation transients obtained from YD. in Mn-depleted PSII membranes in terms of dipolar-induced relaxation enhancement from the non-heme Fe(II). From simulations of the spin-lattice relaxation transients, we obtain the magnitude of the magnetic dipolar interaction between YD. and the non-heme Fe(II), which can be used to calculate the distance between them. Using data on the non-heme Fe(II) in the reaction center of Rhodobacter sphaeroides to model the non-heme Fe(II) in PSII, we calculate a YD.-Fe(II) distance of greater than or equal to 38 A in PSII. This agrees well with the distance predicted from the structure of the bacterial reaction center.     

Ocular tracking as a measure of auditory motion perception.

Motion is a potent sub-modality of vision. Motion cues alone can be used to segment images into figure and ground and break camouflage. Specific patterns of motion support vivid percepts of form, guide locomotion by specifying directional heading and the passage of objects, and in case of an impending collision, the time to impact. Visual motion also drives smooth pursuit eye movements (SPEMs) that serve to stabilize the retinal image of objects in motion. In contrast, the auditory system does not appear to be particularly sensitive to motion. We review the ambiguous status of auditory motion processing from the psychophysical and electrophysiological perspectives. We then report the results of two experiments that use ocular tracking performance as an objective measure of the perception of auditory motion in humans. We examine ocular tracking of auditory motion, visual motion, combined auditory + visual motion and imagined motion in both the frontal plane and in depth. The results demonstrate that ocular tracking of auditory motion is no better than ocular tracking of imagined motion. These results are consistent with the suggestion that, unlike the visual system, the human auditory system is not endowed with low-level motion sensitive elements. We hypothesize however, that auditory information may gain access to a recently described high-level motion processing system that is heavily dependent on 'top-down' influences, including attention.     

Mitochondrial DNA as a marker of molecular diversity: a reappraisal

Over the last three decades, mitochondrial DNA has been the most popular marker of molecular diversity, for a combination of technical ease-of-use considerations, and supposed biological and evolutionary properties of clonality, near-neutrality and clock-like nature of its substitution rate. Reviewing recent literature on the subject, we argue that mitochondrial DNA is not always clonal, far from neutrally evolving and certainly not clock-like, questioning its relevance as a witness of recent species and population history. We critically evaluate the usage of mitochondrial DNA for species delineation and identification. Finally, we note the great potential of accumulating mtDNA data for evolutionary and functional analysis of the mitochondrial genome.     

Endophenotypes as a measure of suicidality

Suicide is thought to result from the harmful interaction of multiple factors that have social, environmental, neurobiological, and genetic backgrounds. Recent studies have suggested that genetic predisposition to suicidal behavior may be independent of the risk of suicide associated to mental disorders, such as affective disorders, schizophrenia, or alcohol dependence. Given the suicidal behavior heterogeneity and its hereditary complexity, the need to find demonstrable intermediate phenotypes that may make it possible to establish links between genes and suicide behaviors (endophenotypes) seems to be necessary. The main objective of this review was to consider the candidate endophenotypes of suicidal behaviors. Due to the recent advances in neuroimaging, we also characterize brain regions implicated in vulnerability to suicide behavior that are influenced by gene polymorphisms associated with suicidal behavior.     

Fluorometric determination of phosphatidylcholine as a measure of phospholipid methylation.

The successive methylation of phosphatidylethanolamine to phosphatidylcholine (phospholipid methylation) has been measured by the incorporation of S-[methyl-3H]adenosylmethionine or colorimetric assay of phosphatidylcholine extracted from adipocyte plasma membranes. A fluorometric assay for phosphatidylcholine was developed to measure phospholipid methylation. This assay is 10 times more sensitive than the colorimetric assay and demonstrates no significant interference with other methylated phospholipids. The fluorometric assay was used to determine a biphasic insulin dose response in adipocyte plasma membranes. This fluorometric assay for phosphatidylcholine represents an alternative method for monitoring phospholipid methylation, especially when increased sensitivity is required.