Prolactin,hypercalcemia and corpuscles of stannius in seawater eels

In intact eels in sea water (SW), ovine prolactin (PRL) treatment induces hypercalcemia, but its mechanism of action, which is discussed, remains to be defined. Corpuscles of Stannius (CSt) are modified simultaneously: two cell categories then become evident. The first cell type (type 1) predominates; it has an oval shape and large granules, it shows a nuclear and nucleolar hypertrophy and a mitotic activity, and appears greatly stimulated by PRL; it may elaborate a hypocalcemic factor (hypocalcin) which would compensate for the PRL-induced hypercalcemia. A similar effect, although slightly less intense, is detected in hypophysectomized-PRL treated eels in SW. A second cell type (type 2), is more elongated, smaller in size, and has an oval nucleus and fine granules. Scarcely less active in SW, it is significantly stimulated by PRL despite an increased blood sodium and potassium level. This experiment does not help to clarify its function.     

Differential Effect of Sodium and Magnesium on the Pituitary of Goldfish Adapted to Calcium-Free Environments

Adaptation to deionized water (DW) affects several cell types in the goldfish. The pars intermedia PAS-positive cells are highly stimulated. Their low response or the absence of changes in goldfish kept in 1/3 Ca-free seawater (SW) and in Ca-free SW-adapted eels, respectively, suggest that sodium and/or magnesium are interfering. To test this hypothesis, young goldfish were adapted to DW supplemented or not with sodium (50 and 140 mM) for 8 and 16 days or with magnesium (16.5 and 50 mM) for 16 and 30 days. Cytological and morphometric studies of the pituitary showed that prolactin (PRL) cell activity was reduced by sodium. Thyrotropic (TSH) cells were stimulated. The activity of melanocyte-stimulating (MSH) cells increased in DW + Na+. Stimulation of the pars intermedia PAS+ cells in DW was partly inhibited by adding sodium; the cellular and nuclear areas increased only moderately, the endoplasmic reticulum (ER) was not conspicuous and mitotic activity disappeared. In DW + Mg²⁺ the activity of PRL, TSH and MSH cells tended to be lower after a long-term adaptation. The response of the PAS+ cells was as high as that noted in DW; complete degranulation, enlargement of the ER and important mitotic activity. Differential responses to Na+ and Mg²⁺ are not due to pH differences in the solutions. External sodium is able then to reduce the response of the PAS+ cells in a Ca-free environment, while magnesium is not inhibitory. Other cell types are also affected by high levels of Na+ and Mg²⁺.     

Cell junctions in the renal tubule of a fresh-water teleost,Salmo gairdneri Rich.

Summary Cell junctions in the renal tubule of the fresh-water rainbow trout were studied with thin-section and freeze-fracture techniques. Gap junctions were restricted to the proximal tubule, which is consistent with other vertebrate classes. Segments I and II of the proximal tubule and the collecting tubule/collecting duct system exhibited a well-developed zonula occludens with anastomosing strands. The distal segment showed a narrow zonula occludens composed of few parallel strands. The structure of the occluding junctions along the renal tubule of this teleost displays several similarities with the pattern of the zonulae occludentes in the amphibian and the mammalian nephron. From these observations, in conjunction with available data from other vertebrate classes, it can be concluded that in the proximal tubule the development of a deep and complex zonula occludens is a general feature of cold-blooded vertebrates.     

Community-based Adapted Tango Dancing for Individuals with Parkinson's Disease and Older Adults

Adapted tango dancing improves mobility and balance in older adults and additional populations with balance impairments. It is composed of very simple step elements. Adapted tango involves movement initiation and cessation, multi-directional perturbations, varied speeds and rhythms. Focus on foot placement, whole body coordination, and attention to partner, path of movement, and aesthetics likely underlie adapted tango’s demonstrated efficacy for improving mobility and balance. In this paper, we describe the methodology to disseminate the adapted tango teaching methods to dance instructor trainees and to implement the adapted tango by the trainees in the community for older adults and individuals with Parkinson’s Disease (PD). Efficacy in improving mobility (measured with the Timed Up and Go, Tandem stance, Berg Balance Scale, Gait Speed and 30 sec chair stand), safety and fidelity of the program is maximized through targeted instructor and volunteer training and a structured detailed syllabus outlining class practices and progression.     

Quantitative calcium measurements in subcellular compartments of Plasmodium falciparum-infected erythrocytes

The acidic food vacuole exerts several important functions during intraerythrocytic development of the human malarial parasite Plasmodium falciparum. Hemoglobin taken up from the host erythrocyte is degraded in the food vacuole, and the heme liberated during this process is crystallized to inert hemozoin. Several anti-malarial drugs target food vacuolar pathways, such as hemoglobin degradation and heme crystallization. Resistance and sensitization to some antimalarials is associated with mutations in food vacuolar membrane proteins. Other studies suggest a role of the food vacuole in ion homeostasis, and release of Ca2+ from the food vacuole may mediate adopted physiological responses. To investigate whether the food vacuole is an intracellular Ca2+ store, which in turn may affect other physiological functions in which this organelle partakes, we have investigated total and exchangeable Ca2+ within the parasite's food vacuole using x-ray microanalysis and quantitative confocal live cell Ca2+ imaging. Apparent free Ca2+ concentrations of approximately 90, approximately 350, and approximately 400 nM were found in the host erythrocyte cytosol, the parasite cytoplasm, and the food vacuole, respectively. In our efforts to determine free intracellular Ca2+ concentrations, we evaluated several Ca2+-sensitive fluorochromes in a live cell confocal setting. We found that the ratiometric Ca2+ indicator Fura-Red provides reliable determinations, whereas measurements using the frequently used Fluo-4 are compromised due to problems arising from phototoxicity, photobleaching, and the strong pH dependence of the dye. Our data suggest that the food vacuole contains only moderate amounts of Ca2+, disfavoring a role as a major intracellular Ca2+ store.     

Synthesis and biological activity of [Tic] didemnin B

A didemnin B analog containing a Tic (1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid) as a conformationally restrained replacement for tyrosine has been synthesized and shown to have comparable potency as a protein biosynthesis inhibitor. Synthetic highlights include an oxidation of an alcohol to an acid in the presence of the sensitive Tic heterocycle and a modified Schmidt-type one-pot macrocyclization.     

Metabolite effectors for short-term nitrogen-dependent enhancement of phosphoenolpyruvate carboxylase activity and decrease of net sucrose synthesis in wheat leaves

It has been demonstrated previously that field pea (Pisum sativum L. cv. Express) grown in hydroponic culture on a complete nutrient solution with low NH₄⁺ concentrations (<0.5 mM) will produce a larger than normal proliferation of nodules. Peas grown in the absence of mineral N in hydroponic culture have been shown to rapidly autoregulate nodulation, forming a static nodule number by 14 to 21 days after planting. The present study further characterizes the effect of NH₄⁺ concentration in hydroponic culture on nodulation and nodule growth. Peas were grown continually for 4 weeks at NH₄⁺ concentrations that were autoregulatory (0.0 mM), stimulatory (0.2 mM) or inhibitory (1.0 mM), or peas were transferred between autoregulatory or NH₄⁺ inhibited and stimulatory solutions after 2 weeks. The peas nodulated as expected when grown under constant autoregulatory, stimulatory or inhibitory concentrations of NH₄⁺. When peas were transferred from the inhibitory (1.0 mM) to the stimulatory solution (0.2 mM) a massive proliferation of nodule primordia over the entire root system was observed within 3 days of the transfer. When they were transferred from the autoregulatory (0.0 mM) to the stimulatory (0.2 mM) solution a 10-day delay occurred before a proliferation in nodule primordia occurred at distal regions of the root system. These findings support our hypothesis that low concentrations (<1.0 mM) of NH₄⁺ in hydroponic culture cause a suppression of autoregulation in pea. In addition, the temporal and spatial differences in nodule proliferation between transfer treatments demonstrate at a whole plant level that autoregulation and NH₄⁺ inhibition suppress early nodule development via different mechanisms.