UV hazard on a summer’s day under Mediterranean conditions, and the protective role of a beach umbrella

Mediterranean beaches are very crowded during summer and, because of the high values of solar UV radiation, the potential risk for human health is relevant. In this study, all-day measurements of biologically effective global and diffuse UV radiation for skin (UVBE_eryt) and eye (UVBE_pker, UVBE_pconj, UVBE_cat) disorders were carried out on differently tilted surfaces on a summers day on a Mediterranean beach. The role played by beach umbrellas in protection from excessive sun exposure was also investigated. Erythema, photokeratitis and cataract seem to require almost the same exposure time to reach the risk threshold dose. Under full sunlight, the highest global and diffuse UV values are reached on surfaces normally oriented towards sunlight and on horizontal surfaces, respectively. Over vertical surfaces, at this northern hemisphere site, global and diffuse UV radiation reaches maxima values in the south-facing direction around noon, while maxima values are reached early in the morning and late in the afternoon over surfaces facing east and west, respectively. The quality of the beach umbrellas protection (efficiency in blocking solar UV radiation) varies with surface orientation; the highest efficiency for our specific site and geometrical conditions occurs over horizontal surfaces, with efficiency being least over vertical surfaces when incident radiation values are still relevant.     

Night — day drift patterns and the size of larvae of two aquatic insects

A test of Allan's (1978) hypothesis about differential drift abundance of mayflies of the genus Baetis between night and day, and the size of larvae was performed at a mountain stream in Idaho. Palisades Creek, Idaho, contains a different species of mayfly, B. tricaudatus, and vertebrate predator, Salmo clarki, than Cement Creek, Colorado (B. bicaudatus, and brook trout, Salvelinus fontinalis). Consequently it was not known if B. tricaudatus would exhibit a similar pattern as its congener in Cement Creek, with large instars tending to avoid daylight drift, as found by Allan (1978). However, similar results were observed in the present study. It appears that the earlier hypothesis may have generality for geographically distinct streams with a different vertebrate predator and mayfly prey. The existence of a similar pattern for chironomid larvae was also tested, however, no such pattern existed. This discrepency between taxa may be due to differential predation, or to inherent differences in drift abilities.     

Comparative Study of 250 mg/day Terbinafine and 100 mg/day Itraconazole for the Treatment of Cutaneous Sporotrichosis

Abstract  

Itraconazole is currently used for the treatment of cutaneous sporotrichosis. Terbinafine at a daily dose of 250 mg has been successfully applied to the treatment of cutaneous sporotrichosis.     

Will the first dominant follicle of the estrous cycle of heifers ovulate following luteolysis on day 7?

The pattern of turnover of dominant follicles involves the sequential growth and regression of two to three dominant follicles during the estrous cycle. The dominant follicle that ovulates is the one that develops concomitantly with the regression of the corpus luteum. The aim of this paper was to determine if the first dominant follicle would ovulate following induction of luteolysis with prostaglandin F2 alpha analogues (PGF) on Day 7 of the cycle. Heifers (n = 43) were checked for estrus (Day 0); their ovaries were scanned daily from Day 6 of the cycle for one week, and the fate of the first dominant follicle was determined. Luteolysis was induced on Day 7 with PGF analogues, and blood samples were taken daily for progesterone and estradiol measurement and at 3-h intervals for 33 h for luteinizing hormone (LH) measurement. Of the 43 heifers given PGF, complete luteolysis occurred in 40 animals. Of these, the first dominant follicle ovulated in 37 heifers; the dominant follicle was not the ovulatory follicle in 2 heifers and the dominant follicle became cystic in one heifer.     

Elucidation of origin of the present day hybrid banana cultivars using the 5′ETS rDNA sequence information

In the present study, our intention was to elucidate the genetic relation of M. acuminata subspecies and analyse the diversity of the M. balbisiana gene-pool using nuclear ribosomal gene loci based marker system. Additionally the obtained information allowed elucidating the structure and ancestry of the nuclear genomes of diploid and triploid cultivars. By establishing the nucleotide sequence of the rDNA locus for M. acuminata and partially for M. balbisiana and their comparative analysis revealed that the 5′ETS region was the most divergent between acuminata and balbisiana genomes. Based on the SNP sites identified in this region a PCR based system was built, which revealed four gene-pools among M. acuminata wild types, while M. balbisiana showed no sequence divergence. The developed markers proved to be a powerful tool in the identification of the acuminata component of diploid and triploid hybrid cultivars and discovery of unexpected genotypes.     

Promotory effect of GA13 on flowering ofAmaranthus — a short day plant

Abstact The three plant types ofAmaranthus namely,A. caudatus f.albiflorus, A. caudatus f.caudatus andA. tricolor var.tristis are qualitative short day plants with critical photoperiods 16.0, 15.5 and 15.0 h, respectively. Gibberellins A₃, A₄₊₇ and A₁₃ affect extension growth, leaf differentiation and floral induction differently. Thus, in all the three plant types ofAmaranthus, whereas, GA₃ and G₄₊₇ enhanced extension growth, GA₁₃ was completely ineffective under both, 24- and 8-h photoperiods. None of the three gibberellins could affect the leaf differentiation. In all the three plant types, flowering was promoted by GA₁₃ and not by other gibberellins tried. GA₁₃ caused promotion was manifested in two manners, firstly by lowering the critical dark period requirement in each inductive cycle, and secondly by shortening the total period taken for the initiation of inflorescence primordia under inductive photoperiods. The floral induction by gibberellins inAmaranthus is contrary to the gibberellin-anthesin concept of Chailakhyan. It is suggested that gibberellins other than GA₃ may be playing an important role in floral morphogenesis of short day plants.     

The impact of time of day on the gait and balance control of Alzheimer’s patients

Alzheimer’s patients suffer from circadian dysregulation. The aim of this study was to examine the evolution of balance control and gait at different times of the day (11:00, 14:00, 18:00) in order to identify whether Alzheimer’s patients were more likely to fall at certain periods of the day. Spatio-temporal parameters of centre of foot pressure displacements were measured with a force platform and spatio-temporal parameters of walking were evaluated with a gait analysis device. The results highlighted that balance control was worse in the evening and the afternoon than in the morning. Furthermore, the walking speed was faster and support duration, swing duration and cycle duration were shorter in the evening than in the morning and afternoon. The combined analysis of balance control and gait parameters revealed that balance control and walking are concomitantly altered in the evening which increases the fall risk in the evening, in comparison with the morning, for Alzheimer’s patients.     

Evaluation of day one embryo quality and IVF outcome – a comparison of two scoring systems

Background  

The aim of our retrospective study was to compare the clinical usefulness of two non-invasive embryo scoring systems based either on a simplified pronuclear morphology of the zygote or on early cleavage rate, as well as their combination, for the selection of embryos with the best implantation potential in embryo transfer (ET).     

Antigenic similarity between the β-subunits of the ATPases of a bacterium,a yeast and a higher plant

Antiserum raised against the β-subunit of wheat (Triticum aestivum) chloroplast ATPase cross-reacts with a 51000 protein located in the membrane fraction of Escherichia coli. The differential solubility of this polypeptide after chloroform treatment of unc⁺ and uncD409 strains indicates that this cross-reacting polypeptide is the bacterial β-subunit of ATPase. Thus a high degree of conservation of antigenic determinant sites exists between a bacterial β-subunit and the β-subunit of a monocot. This conservation also seems to extend to the β-subunit of mitochondrial ATPase of yeast (Saccharomyces cerevisiae).     

Influence of the radial profile of the electric potential on the confinement of a high-β two-component plasma in a gas-dynamic trap

One of the most important problems to be studied in the gas-dynamic trap (GDT) facility is the investigation of MHD stability and cross-field transport in a plasma with a relatively high value of β = πp/B ². Recent experiments demonstrated that the radial electric field produced in the plasma by using radial limiters and coaxial end plasma collectors improves plasma stability in axisymmetric magnetic mirror systems without applying special MHD stabilizers. The experimental data presented in this work show that stable plasma confinement can be achieved by producing a radial potential drop across a narrow region near the plasma boundary. Creating radial electric fields of strength 15–40 V/cm causes a shear plasma flow, thereby substantially increasing the plasma confinement time. When all the radial electrodes were grounded, the confinement was unstable and the plasma confinement time was much shorter than the characteristic time of plasma outflow through the magnetic mirrors. Measurements of cross-field plasma fluxes with the use of a specially designed combined probe show that, in confinement modes with differential plasma rotation, transverse particle losses are negligibly small as compared to longitudinal ones and thus can be ignored. It is also shown that, when the GDT plasma is in electric contact with the radial limiters and end collectors, the growth rate of interchange instability decreases considerably; such a contact, however, does not ensure complete MHD stability when the electrodes are at the same potential.     

Does the immune system of a mouse age faster than the immune system of a human?

One of the characteristics of all somatic cells is a finite life span. Cells may proliferate until they reach a point after which, although they are metabolically active, they can no longer produce daughter cells. This observation is central to the clonal exhaustion hypothesis, a mechanism cited to explain age-associated immune dysfunction. In this hypothesis, repeated division of lymphocytes leads to a replicative limit, after which they enter the senescent phase but are not lost from the pool of T cells. Advancing age would then be associated with an increase in the number of T cells that are unable to proliferate to a stimulus which induces a proliferative response in T cells from younger individuals. This hypothesis seems both logical and reasonable and is supported by data from both humans and mice with the demonstration of an age-related accumulation of senescent T cells in both species. However, there is an apparent paradox. The paradox arises because the onset of immunosenescence appears to be more closely linked to the life span of the animal rather than the life span of the lymphocyte. BioEssays 21:519–524, 1999. © 1999 John Wiley & Sons, Inc.     

Making a Mechanical Organism Being the fourth in a series of essays on the materials of nature

Most multicellular organisms can be categorised by two words： hierarchy and composite. The underlying fractal geometry of nature - at least in terms of provision of infrastructure - provides much of the hierarchy, although many materials for which infrastructure is not an integral factor are also strongly hierarchical. Plants can therefore be modelled using recursive computer programs which add structures as the size increases. However, problems with mechanical stability also increase as the structure grows, so the plant changes from deriving stiffness from intevaal pressure to cross-linking the cell wall components permanently. However, this compromises the ability of the plant to grow and repair itself.     

Evolution of the genetic machinery of the visual cycle: a novelty of the vertebrate eye?

The discovery in invertebrates of ciliary photoreceptor cells and ciliary (c)-opsins established that at least two of the three elements that characterize the vertebrate photoreceptor system were already present before vertebrate evolution. However, the origin of the third element, a series of biochemical reactions known as the "retinoid cycle," remained uncertain. To understand the evolution of the retinoid cycle, I have searched for the genetic machinery of the cycle in invertebrate genomes, with special emphasis on the cephalochordate amphioxus. Amphioxus is closely related to vertebrates, has a fairly prototypical genome, and possesses ciliary photoreceptor cells and c-opsins. Phylogenetic and structural analyses of the amphioxus sequences related with the vertebrate machinery do not support a function of amphioxus proteins in chromophore regeneration but suggest that the genetic machinery of the retinoid cycle arose in vertebrates due to duplications of ancestral nonvisual genes. These results favor the hypothesis that the retinoid cycle machinery was a functional innovation of the primitive vertebrate eye.     

Preparation of a glycosynthase from the β-glycosidase of the Archaeon Pyrococcus horikoshii

The β-glycosidase from the hyperthermophilic Archaeon Pyrococcus horikoshii (Phoβ-gly) is a monomeric enzyme with wide substrate specificity belonging to family 1 of glycoside hydrolases classification. Inspection of the three-dimensional structure of the enzyme, recently resolved, showed that Phoβ-gly is membrane bound and that the residues putatively involved in the catalytic activity are Glu155 and Glu324 working as the general acid/base and the nucleophile of the reaction, respectively. We show here that mutation of the latter completely eliminated the activity of the enzyme and that it could be reactivated in the presence of sodium formate. Analysis of the products obtained in the presence of sodium formate buffer pH 4.0 at 75°C showed that the Glu324Gly mutant acts as a hyperthermophilic glycosynthase.     

Time–activity budget of greater rheas (Rhea americana, Aves) on a human-disturbed area: the role of habitat, time of the day, season and group size

The aim of this study was to evaluate activity–time budget, habitat use and how seasonality and group size influence the expression of greater rhea behaviours. Greater rheas are threatened South American birds; habitat loss, predation and hunting are the main factors responsible for population declines. The study was conducted in farmlands within a matrix of commercial Eucalyptus plantation and remnants of natural habitats of cerrado vegetation (savannah-like) in southeastern Brazil. Rhea groups were located visually in different habitats visited monthly from January 2004 to December 2005. Time spent searching greater rheas in each habitat was equally distributed. Data were collected using scan sampling with instantaneous recording of behaviours every minute. The time–activity budget of greater rheas was influenced by habitat structure, time of the day, season and group size. Rheas spent more time in open areas than in forested areas (p < 0.001). Vigilance behaviours were more displayed in forested areas, in the dry season and by solitary and small groups of birds. Resting behaviours occurred more often in open lands and within groups with more than three rheas. Food availability, good visibility and low human presence are the possible factors for the preference of greater rheas for pasturelands. The results support the resource availability hypothesis, where it is expected that habitats with a higher food availability will be more used by the animals, group size hypothesis, where the scarcity of resources will lead to smaller groups of animals and that forestry modifies greater rheas habitat use and behaviours.     

Brief communication: molecular analysis of the Kwäday Dän Ts'finchi ancient remains found in a glacier in Canada

DNA was extracted from the frozen remains of a man found in the northwest corner of British Columbia, Canada, in 1999. His clothing was radiocarbon-dated at ca. 550 years old. Nitrogen and carbon content in whole bone and collagen-type residue extracted from both bone and muscle indicated good preservation of proteinaceous macromolecules. Restriction enzyme analysis of mitochondrial DNA (mtDNA) determined that the remains belong to haplogroup A, one of the four major Native American mtDNA haplogroups. Data obtained by PCR direct sequencing of the mtDNA control region, and by sequencing the clones from overlapping PCR products, were duplicated by an independent laboratory. Comparison of these mtDNA sequences with those of North American, Central American, South American, East Siberian, Greenlandic, and Northeast Asian populations indicates that the remains share an mtDNA type with North American, Central American, and South American populations.