Calcium-sensitivity of brain microtubule proteins in the presence of S-100 proteins

In the presence of the usual 0.1 M Mes buffer, pH 6.7, mM free Ca2+ levels are required for half-maximal decrease in the rate and extent of brain microtubule protein (MTP) assembly in the absence of ox brain S-100, while microM free Ca2+ levels are sufficient in the presence of S-100. At the same pH 6.7, but in the presence of 0.12 M KCl, as low as 1.5 microM free Ca2+ is sufficient for S-100 to produce half-maximal reduction in the rate of assembly, while as high as 0.5 mM free Ca2+ is required in the absence of S-100. Similar results are obtained with rat brain S-100 (S-100b), indicating that single S-100 iso forms are equipotent in affecting the MTP assembly. At pH 7.5, MTPs are remarkably resistant to Ca2+ in the absence of S-100. In the presence of S-100, not only is the free Ca2+ concentration required for complete inhibition of assembly at least one order of magnitude smaller than that required in the absence of S-100, but significant S-100-dependent inhibition of assembly occurs in the absence of Ca2+. Under the two conditions where S-100 is particularly effective in inhibiting the assembly, i.e. at pH 6.7 in the presence of KCl and at pH 7.5, S-100 increases the disassembly rate even in the presence of microM Ca2+ levels. Our results suggest that the free Ca2+ concentration regulates the way S-100 disassembles microtubules (MTs): at microM Ca2+ levels, S-100 sequesters tubulin with concomitant increase in the disassembly rate; at mM Ca2+ levels, the S-100-Ca2+ complex probably interacts with MTs producing endwise disassembly.     

Immunohistochemical localization of annexin V (CaBP33) in rat organs.

We investigated the cellular distribution of annexin V (CaBP33) in rat tissues by immunohistochemistry. Several cell types were shown to express the protein. Glial cells in the cerebellum and in the optic nerve, the corneal epithelium, the posterior epithelium in the iris, chondrocytes, skeletal muscle cells and cardiomyocytes, the capillary endothelial cells in many organs, the muscularis mucosae and the muscular layer in the intestinal tract, hepatocytes, Müller cells in the retina, the lens fibers, Sertoli and Leydig cells in the testis, and smooth muscle cells in the epididymis and bronchi displayed intense immunostaining. In the adrenal gland, only the cortex showed immunoreaction product. In the kidney, no apparent staining of renal cells was observed, whereas endothelial cells of peritubular capillaries were stained. In the heart, annexin V was found associated exclusively with the sarcolemma and intercalated discs, as opposed to the diffuse distribution of the protein in skeletal muscle cells. In the spleen, only reticular elements in the white pulp and endothelial cells in the red pulp appeared to be immunostained. The present data complement the biochemical work thus far done on annexin V and suggest that the protein is neither restricted to secretory cells nor exclusively related to exocytotic events in secretory cells.     

Spatio-temporal distribution and abundance of <Emphasis Type="Italic">Euphausia crystallorophias</Emphasis> in Terra Nova Bay (Ross Sea,Antarctica) during austral summer

Average abundance values for Euphausia crystallorophias in the shelf region of Terra Nova Bay were generally high. Mean number of adults and juveniles were 20 and 87 ind/m², respectively, while larval concentrations were much higher, reaching a mean of 14,764 ind/m². Euphausia crystallorophias were very patchy in their distribution during all stages of their life cycle. The distribution patterns of E. crystallorophias in TNB seem to be strictly correlated both to hydrological features such as the presence of polynyas, pack-ice zone and certain temperatures values. According to our data, E. crystallorophias spawned from early October to early January. For the two age groups (0+ and 1+) an average growth rate of 0.074 and 0.076 mm/day was found, respectively. The mean biomass of larval E. crystallorophias (from Metanauplius to Furcilia I) in January was estimated as 84 mg WW/m². This article belongs to a special topic: Five articles on Sea-ice communities in Terra Nova Bay (Ross Sea), coordinated by L. Guglielmo and V. Saggiomo, appear in this issue of Polar Biology. The studies were conducted in the frame of the National Program of Research in Antarctica (PNRA) of Italy.     

Transgenic ryegrasses (Lolium spp.) with down-regulation of main pollen allergens

Ryegrass pollen (Lolium species) is a widespread source of air-borne allergens and is a major cause of hayfever and seasonal allergic asthma, which affect approximately 25% of the population in cool temperate climates. The main allergens of ryegrass pollen are the proteins Lol p 1 and Lol p 2. These proteins belong to two major classes of grass pollen allergens to which over 90% of pollen-allergic patients are sensitive. The functional role in planta of these pollen allergen proteins remains largely unknown. Here we describe the generation and analysis of transgenic plants with reduced levels of the main ryegrass pollen allergens, Lol p 1 and Lol p 2 in the most important worldwide cultivated ryegrass species, L. perenne and L. multiflorum. These transgenic plants will allow the study of the functional role in planta of these pollen proteins and the determination of potential for development of hypo-allergenic ryegrass cultivars.     

Effect of S-100 protein on assembly of brain microtubule proteins in vitro

S-100 protein inhibits the assembly of brain microtubule proteins in vitro in the presence of 10 microM free Ca2+. The S-100 effect is generally greater on the rate than on the extent of assembly, and even greater as the microtubule protein concentration decreases and the time of preincubation between S-100 and microtubule proteins before GTP addition increases, at a given S-100/tubulin dimer molar ratio. The S-100 effect is greatly enhanced in the presence of physiological concentrations of K+ and is completely reversed by EGTA.     

Echocardiography in patients with hypertrophic cardiomyopathy: usefulness of old and new techniques in the diagnosis and pathophysiological assessment

Hypertrophic cardiomyopathy (HCM) is one of the most common inherited cardiomyopathy. The identification of patients with HCM is sometimes still a challenge. Moreover, the pathophysiology of the disease is complex because of left ventricular hyper-contractile state, diastolic dysfunction, ischemia and obstruction which can be coexistent in the same patient. In this review, we discuss the current and emerging echocardiographic methodology that can help physicians in the correct diagnostic and pathophysiological assessment of patients with HCM.