Seasonal occupancy and connectivity amongst nearshore flats and reef habitats by permit Trachinotus falcatus: considerations for fisheries management

We used acoustic telemetry to quantify permit Trachinotus falcatus habitat use and connectivity in proximity to the Florida Keys, USA, and assessed these patterns relative to current habitat and fisheries management practices. From March 2017 to June 2018, 45 permit tagged within 16 km of the lower Florida Keys were detected at stationary acoustic receivers throughout the south Florida region, the majority of which remained within the Special Permit Zone, where more extensive fisheries harvest regulations are implemented. There was a high level of connectivity between nearshore flats (i.e., <3 m water depth) and the Florida reef tract (FRT; 15–40 m water depth), with 75% of individuals detected in both habitats. These locations probably function primarily as foraging and spawning habitats, respectively. Permit occupancy on the FRT peaked during the months of March–September, with the highest number of individuals occurring there in April and May. Specific sites on the FRT were identified as potentially important spawning locations, as they attracted a high proportion of individuals that exhibited frequent visits with high residency durations. There were also significant positive relationships between seasonal habitat-use metrics on the FRT and an empirical permit gonadosomatic index. Large aggregations of permit at spawning sites on the FRT are potentially vulnerable to the effects of fishing (including predation during catch and release) at a critical point in their life cycle. These data on permit space use and movement, coupled with knowledge of stressors on their ecology, provide insights for implementing science-based strategic management plans.     

A POPULATION STUDY OF CHARA ZEYLANICA IN TEXAS,OKLAHOMA, AND NEW MEXICO

Examination of 140 collections of Chara zeylanica from 3 southwestern states shows that a strong dichotomy exists in the collections. Some produce 4-plated antheridia while others produce 8-plated antheridia. Absolute separation of the study material is possible on the basis of plate number. In addition, 3 other characters (length/width ratio of oospores; fertility of first branchlet node; and number of distal ecorticate branchlet internodes) show strong correlation with the antheridial type. Preliminary chromosomal work indicates that a segregation at this level may also be possible. In 4-plated collections examined, n = 28; 8-plated collections are usually n = 56; however, a few 8-plated collections are n = 42. No conclusion has been reached regarding the status of the latter collections.     

Pre-pre-B cells containing only cytoplasmic B220 can be induced by dendritic cells and T cells to differentiate in vitro

We have derived from spleens of nude mice early B lineage cells that were phenotypically compatible with a pre-pre-B cell stage of differentiation. Although these cells containing large basophilic granules had the B lymphocyte antigen B220, in the cytoplasm, they had no surface B220, no cytoplasmic or surface immunoglobulin heavy or light chains, no surface Thy-1, and no surface Ia. In addition, they appeared to have little or no heavy chain gene rearrangements, including the D to J that occurs on both chromosomes prior to the VH rearrangement that forms the code for the C mu heavy chain polypeptide. Cells at even this early stage of differentiation could be induced by DC-T to express B220 on the surface and to synthesize and then to secrete immunoglobulins. These phenotypic changes were associated with a morphologic change in the cells to a lymphoblastoid appearance. Different patterns of immunoglobulin secretion resulted when pre-pre-B cells were cocultivated with DC-T from different tissues; SP DC-T induced the secretion of only IgM, PP DC-T induced the secretion of IgM as well as IgG and IgA. The early inductive event(s) appeared to occur during cell-cell contact in aggregates of the inducing DC-T and the pre-pre-B cells.     

Excitatory Amino Acid Synthesis in Hypoxic Brain Slices: Does Alanine Act as a Substrate for Glutamate Production in Hypoxia?

Abstract: Excitatory amino acids are an important cause of cell death in the hypoxic and ischaemic brain. Neuronal glutamate stores are depleted rapidly in hypoxia, but alanine production rises under such conditions and has been suggested to be a potential precursor of glutamate. To test this hypothesis, we have investigated amino acid metabolism using ¹³C NMR with superfused guinea pig cortical slices subjected to varying degrees of hypoxia. During severe hypoxia, brain slices metabolising 5 m M [2-¹³C]pyruvate exported [2-¹³C]alanine into the superfusion fluid. The metabolic fate of alanine during normoxia and hypoxia was tested by superfusion of brain slices with 10 m M glucose and 2 m M [2-¹³C, ¹⁵N]alanine. Metabolism of exogenous alanine leads to the release of aspartate into the superfusion fluid. The pattern of labelling of aspartate indicated that it was synthesised via the glial-specific enzyme pyruvate carboxylase. ¹³C-labelled glutamate was produced with both normoxia and hypoxia, but concentrations were 30-fold lower than for labelled aspartate. Thus, although substantial amounts of glutamate are not synthesised from alanine in hypoxia, there is significant production of aspartate, which also may have deleterious effects as an excitatory amino acid.