The importance of considering genetic diversity in shark and ray conservation policies

Many populations of elasmobranchs (sharks and rays) are experiencing severe declines due to the high demand for shark fins in Asia, the activities of unregulated fisheries, and increases in shark and ray catches. Recently, the effects of the decline in the populations of marine fish species on genetic diversity have drawn increasing attention; however, only a few studies have addressed the genetic diversity of shark and ray populations. Here, we report the results of a quantitative analysis of the genetic diversity of shark and ray species over the past 20 years and discuss the importance and utility of this genetic information for fisheries management and conservation policies. Furthermore, we suggest future actions important for minimizing the gaps in our current knowledge of the genetic diversity of shark and ray species and to minimize the information gap between genetic scientists and policymakers. We suggest that shark and ray fisheries management and conservation policies consider genetic diversity information, such as the management unit, effective population size (Ne), haplotype and nucleotide diversity, observed heterozygosity, and allelic richness, because the long-term survival of a species is strongly dependent on the levels of genetic diversity within and between populations. In addition, sharks and rays are a group of particular interest for genetic conservation due to their remarkable life histories.     

Ex vivo Mimicry of Normal and Abnormal Human Hematopoiesis

Hematopoietic stem cells require a unique microenvironment in order to sustain blood cell formation¹; the bone marrow (BM) is a complex three-dimensional (3D) tissue wherein hematopoiesis is regulated by spatially organized cellular microenvironments termed niches^2-4. The organization of the BM niches is critical for the function or dysfunction of normal or malignant BM⁵. Therefore a better understanding of the in vivo microenvironment using an ex vivo mimicry would help us elucidate the molecular, cellular and microenvironmental determinants of leukemogenesis⁶.Currently, hematopoietic cells are cultured in vitro in two-dimensional (2D) tissue culture flasks/well-plates⁷ requiring either co-culture with allogenic or xenogenic stromal cells or addition of exogenous cytokines⁸. These conditions are artificial and differ from the in vivo microenvironment in that they lack the 3D cellular niches and expose the cells to abnormally high cytokine concentrations which can result in differentiation and loss of pluripotency^9,10.Herein, we present a novel 3D bone marrow culture system that simulates the in vivo 3D growth environment and supports multilineage hematopoiesis in the absence of exogenous growth factors. The highly porous scaffold used in this system made of polyurethane (PU), facilitates high-density cell growth across a higher specific surface area than the conventional monolayer culture in 2D¹¹. Our work has indicated that this model supported the growth of human cord blood (CB) mononuclear cells (MNC)¹² and primary leukemic cells in the absence of exogenous cytokines. This novel 3D mimicry provides a viable platform for the development of a human experimental model to study hematopoiesis and to explore novel treatments for leukemia.     

Recombinant biosynthesis of bacterial cellulose in genetically modified Escherichia coli

Bioprocess and Biosystems Engineering - Bacterial cellulose (BC) exhibits unique properties such as high purity compared to plant-based cellulose; however, commercial production of BC has remained...     

Environmental enrichment effects on the reproductive behavior of captive nurse sharks Ginglymostoma cirratum

Environmental Biology of Fishes - Nurse sharks (Ginglymostoma cirratum, Ginglymostomatidae) are one of the most exhibited shark species in aquariums worldwide. However, in these locations, their...     

Manufacturing Of Robust Natural Fiber Preforms Utilizing Bacterial Cellulose as Binder

A novel method of manufacturing rigid and robust natural fiber preforms is presented here. This method is based on a papermaking process, whereby loose and short sisal fibers are dispersed into a water suspension containing bacterial cellulose. The fiber and nanocellulose suspension is then filtered (using vacuum or gravity) and the wet filter cake pressed to squeeze out any excess water, followed by a drying step. This will result in the hornification of the bacterial cellulose network, holding the loose natural fibers together.Our method is specially suited for the manufacturing of rigid and robust preforms of hydrophilic fibers. The porous and hydrophilic nature of such fibers results in significant water uptake, drawing in the bacterial cellulose dispersed in the suspension. The bacterial cellulose will then be filtered against the surface of these fibers, forming a bacterial cellulose coating. When the loose fiber-bacterial cellulose suspension is filtered and dried, the adjacent bacterial cellulose forms a network and hornified to hold the otherwise loose fibers together.The introduction of bacterial cellulose into the preform resulted in a significant increase of the mechanical properties of the fiber preforms. This can be attributed to the high stiffness and strength of the bacterial cellulose network. With this preform, renewable high performance hierarchical composites can also be manufactured by using conventional composite production methods, such as resin film infusion (RFI) or resin transfer molding (RTM). Here, we also describe the manufacturing of renewable hierarchical composites using double bag vacuum assisted resin infusion.     

Inhibition of marrow granulocytic colony formation by phytohemagglutinin

The effect of phytohemagglutinin (PHA) on the growth and number of granulocytic colonies (GC) developing on agar from bone marrow and spleen cells of normal and erythroleukemic mice inoculated with Rauscher leukemogenic virus was studied. Equal number of marrow cells from erythroleukemic mice produced twice as many colonies as those from normal mice. The number of GC developing from either normal and leukemic spleen cells was only 20% to 25% of that arising from marrow cells. The number of cells within each colony was significantly larger in GC formed by myelogenous leukemic cells than those arising from normal cells even though they had similar morphologic features. The addition of 100 μg of PHA per 10⁵ cells reduced the number of GC arising from normal and leukemic cells by 35% and 50%, respectively. Treatment with periodate which mainly inhibits its mitogenic activity, abolished the inhibitory effects of PHA on proliferation of granulocytic cells.     

Anisotropic surface chemistry of crystalline pharmaceutical solids

The purpose of this study was to establish the link between the wetting behavior of crystalline pharmaceutical solids and the localized surface chemistry. A range of conventional wetting techniques were evaluated and compared with a novel experimental approach: sessile drop contact angle measurements on the individual facets of macroscopic (>1 cm) single crystals. Conventional measurement techniques for determining surface energetics such as capillary rise and sessile drops on powder compacts were found not to provide reliable results. When the macroscopic crystal approach was used, major differences for advancing contact angles, θ_a, of 0 waterwere observed—as low as 16° on facet (001) and as high as 68° on facet (010) of form I paracetamol. θ_a trends were in excellent agreement with X-ray photoelectron spectroscopy surface composition and known crystallographic structures, suggesting a direct relationship to the local surface chemistry. Inverse gas chromatography (IGC) was further used to probe the surface properties of milled and unmilled samples, as a function of particle size. IGC experiments confirmed that milling exposes the weakest attachment energy facet, with increasing dominance as particle size is reduced. The weakest attachment energy facet was also found to exhibit the highest θ_a for water and to be the 0 most hydrophobic facet. This anisotropic wetting behavior was established for a range of crystalline systems: paracetamol polymorphs, aspirin, and ibuprofen racemates. θ_a was 0 found to be very sensitive to the local surface chemistry. It is proposed that the hydrophilicity/hydrophobicity of facets reflects the presence of functional groups at surfaces to form hydrogen bonds with external molecules.