Sexual dimorphisms in the dermal denticles of thelesser-spotted catshark, Scyliorhinus canicula (Linnaeus, 1758)

The dermal layers of several elasmobranch species have been shown to be sexually dimorphic. Generally, when this occurs the females have thicker dermal layers compared to those of males. This sexual dimorphism has been suggested to occur as a response to male biting during mating. Although male biting as a copulatory behaviour in Scyliorhinus canicula has been widely speculated to occur, only relatively recently has this behaviour been observed. Male S. canicula use their mouths to bite the female's pectoral and caudal fins as part of their pre-copulatory behaviour and to grasp females during copulation. Previous work has shown that female S. canicula have a thicker epidermis compared to that of males. The structure of the dermal denticles in females may also differ from that of males in order to protect against male biting or to provide a greater degree of friction in order to allow the male more purchase. This study reveals that the length, width and density of the dermal denticles of mature male and female S. canicula are sexually dimorphic across the integument in areas where males have been observed to bite and wrap themselves around females (pectoral fin, area posterior to the pectoral fin, caudal fin, and pelvic girdle). No significant differences in the dermal denticle dimensions were found in other body areas examined (head, dorsal skin and caudal peduncle). Sexually dimorphic dermal denticles in mature S. canicula could be a response to male biting/wrapping as part of the copulatory process

The effect of herbicides, pesticides, and fertilizers on the optical properties of water

A reflectometer accessory for a spectrophotometer was designed and constructed in our laboratory. Using distilled water as the reflectance standard, the reflectometer was used to measure relative specular reflectance of 0.5M aqueous solutions of K2SO4 and NH4H2PO4 in the 2-12m wavelength region and for 1M (NH2)2CO in the 2-20m wavelength region for infrared radiant flux incident at about 70 degrees and linearly polarized perpendicular to the plane of incidence. Absolute reflectances of the solutions were computed for 70 degrees angle of incidence by using the relative reflectance measurements, one of the Fresnel equations, and the optical constants of water. The optical constants of the aqueous solutions were then computed by applying a Kramers-Kronig phase-shift dispersion analysis to the absolute reflectance spectra. The report provides a description of the instrumentation and the experimental procedures for making the measurements. The relative reflectances, absolute reflectances, and optical constants are presented in graphical form in the text and are tabulated in Appendix I. Spectral signatures characteristic of the solutes are discussed in the text. In addition, further investigations of the optical constants of distilled water were made in that they are related to the investigations of aqueous solutions. The work on distilled water was accomplished in cooperation with Dr. Dudley Williams at Kansas State University. A reprint describing the work is presented in Appendix I.Project # A-030-MO Agreement # 14-31-0001-302

Ependymin Immunoreactivity in Limulus polyphemus

Ependymin is a neurotrophic factor found during certain cellular events related to neuronal development, cellular regeneration, and memory consolidation. Since its discovery in goldfish in 1976, ependymin has been partially sequenced and shows notable conservation through many different species. This allowed for the development of an 8 aa antibody against ependymin which can be used to identify the protein\u27s presence in various tissues. Using immunohistological techniques we have attempted to determine the location of ependymin in several stages of Limulus development. Our preliminary fluorescent staining of whole-mount crabs indicates a strong presence of ependymin throughout the central nervous system in the 1st, 3rd and 4th juvenile instar stages

Quantifying physiological influences on otolith microchemistry

Trace element concentrations in fish earstones (‘otoliths’) are widely used to discriminate spatially discrete populations or individuals of marine fish, based on a commonly held assumption that physiological influences on otolith composition are minor, and thus variations in otolith elemental chemistry primarily reflect changes in ambient water chemistry. We carried out a long-term (1-year) experiment, serially sampling seawater, blood plasma and otoliths of mature and immature European plaice (Pleuronectes platessa L.) to test relationships between otolith chemistry and environmental and physiological variables. Seasonal variations in otolith elemental composition did not track seawater concentrations, but instead reflected physiological controls on metal transport and biokinetics, which are likely moderated by ambient temperature. The influence of physiological factors on otolith composition was particularly evident in Sr/Ca ratios, the most widely used elemental marker in applied otolith microchemistry studies. Reproduction also triggered specific variations in otolith and blood plasma metal chemistry, especially Zn/Ca ratios in female fish, which could potentially serve as retrospective spawning indicators. The influence of physiology on the trace metal composition of otoliths may explain the success of microchemical stock discrimination in relatively homogenous marine environments, but could complicate alternative uses for trace element compositions in biominerals of higher organism

Minihepcidins are rationally designed small peptides that mimic hepcidin activity in mice and may be useful for the treatment of iron overload

Iron overload is the hallmark of hereditary hemochromatosis and a complication of iron-loading anemias such as β-thalassemia. Treatment can be burdensome and have significant side effects, and new therapeutic options are needed. Iron overload in hereditary hemochromatosis and β-thalassemia intermedia is caused by hepcidin deficiency. Although transgenic hepcidin replacement in mouse models of these diseases prevents iron overload or decreases its potential toxicity, natural hepcidin is prohibitively expensive for human application and has unfavorable pharmacologic properties. Here, we report the rational design of hepcidin agonists based on the mutagenesis of hepcidin and the hepcidin-binding region of ferroportin and computer modeling of their docking. We identified specific hydrophobic/aromatic residues required for hepcidin-ferroportin binding and obtained evidence in vitro that a thiol-disulfide interaction between ferroportin C326 and the hepcidin disulfide cage may stabilize binding. Guided by this model, we showed that 7–9 N-terminal amino acids of hepcidin, including a single thiol cysteine, comprised the minimal structure that retained hepcidin activity, as shown by the induction of ferroportin degradation in reporter cells. Further modifications to increase resistance to proteolysis and oral bioavailability yielded minihepcidins that, after parenteral or oral administration to mice, lowered serum iron levels comparably to those after parenteral native hepcidin. Moreover, liver iron concentrations were lower in mice chronically treated with minihepcidins than those in mice treated with solvent alone. Minihepcidins may be useful for the treatment of iron overload disorders

Exploring Perceptions of Sugar Sweetened Beverages Among Early Adolescents in Worcester, MA: a Qualitative Study

Background: Among adolescents, sugar-sweetened beverages (SSBs) are the primary source of added dietary sugar and constitute 10-15% of their total caloric intake. A range of factors influence adolescent dietary behaviors and food choices. This study aimed to explore adolescents\u27 attitudes and knowledge about SSBs, how they receive messages about SSBs, and motivations for SSB consumption. Methods: We conducted 5 focus groups with youth aged 12-14 years that attend one of the eight Youth Connect programs in Worcester, MA in 2016-2017. Groups were sex-specific because of changes during adolescence and experiences with body image and health behaviors between the groups. A semi-structured guide was used to facilitate a discussion with adolescents\u27 around SSBs. The audio recorded data were transcribed and all transcripts were double coded. The data were analyzed using thematic analysis. Results: Discussions included 16 boys in three focus groups and 17 girls in two groups. Participants were 12-14 years old, 27% identified as Hispanic, 24% black and 33% white. One third speaks more than one language at home and the majority consume SSBs daily. Qualitative analysis led to the identification and classification of various subdimensions under the following analytic categories: Attitudes, Motivations, Knowledge, and SSB Messaging. Common themes that emerge under each category will be reported. Analyses are in progress. Conclusions: This research will present a deeper understanding of factors that influence Worcester adolescents\u27 beverage choices from their own perspective. The information can be used in public health messaging in Worcester around obesogenic behaviors such as excess caloric intake from SSBs