Increasing dominance of large lianas in Amazonian forests

Ecological orthodoxy suggests that old-growth forests should be close to dynamic equilibrium, but this view has been challenged by recent findings that neotropical forests are accumulating carbon and biomass, possibly in response to the increasing atmospheric concentrations of carbon dioxide. However, it is unclear whether the recent increase in tree biomass has been accompanied by a shift in community composition. Such changes could reduce or enhance the carbon storage potential of old-growth forests in the long term. Here we show that non-fragmented Amazon forests are experiencing a concerted increase in the density, basal area and mean size of woody climbing plants (lianas). Over the last two decades of the twentieth century the dominance of large lianas relative to trees has increased by 1.7-4.6% a year. Lianas enhance tree mortality and suppress tree growth, so their rapid increase implies that the tropical terrestrial carbon sink may shut down sooner than current models suggest. Predictions of future tropical carbon fluxes will need to account for the changing composition and dynamics of supposedly undisturbed forests.     

Coated vesicles in the rat adrenal glomerular zone after a low-sodium diet.

In rats subjected to a low-sodium diet, a great activity was observed of the coated vesicles at Golgi complex and cell surfaces of glomerular adrenal zone. These findings are related to the function of these organoids in the uptake and transport of necessary substances under stimulating conditions of the zone.     

Regulatory peptide receptors: visualization by autoradiography

The receptors for regulatory peptides have been extensively characterized using radioligand binding techniques. By combining these binding techniques with autoradiography it is possible to visualize at the light and electron microscopic levels the anatomical and cellular localization of these receptors. In this review we discuss the procedures used to label peptide receptors for autoradiography and the peculiarities of peptides as ligands. The utilization of autoradiography in mapping peptide receptors in brain and peripheral tissues, some of the new insights revealed by these studies particularly the problem of 'mismatch' between endogenous peptides and receptors, the existence of multiple receptors for a given peptide family and the use of peptide receptor autoradiography in human tissues are also reviewed.     

Coated vesicles in the rat adrenal glomerular zone after a low-sodium diet

Summary In rats subjected to a low-sodium diet, a great activity was observed of the coated vesicles at Golgi complex and cell surfaces of glomerular adrenal zone. These findings are related to the function of these organoids in the uptake and transport of necessary substances under stimulating conditions of the zone.     

Gamma-tubulin is a centrosomal protein required for cell cycle-dependent microtubule nucleation.

gamma-Tubulin is a newly identified member of the tubulin family whose sequence is highly conserved from yeast to man. This minor microtubule protein is localized to the microtubule organizing centres and a mutation in the gene encoding it produces a microtubuleless mitotic arrest in the filamentous fungus Aspergillus nidulans. Here we investigate the in vivo function of gamma-tubulin in mammalian cells using a synthetic peptide to generate a polyclonal antibody that binds to a highly conserved segment of gamma-tubulin. After microinjection into cultured mammalian cells, immunofluorescence localization revealed that this antibody binds to native centrosomes at all phases of the cell cycle. In the presence of the gamma-tubulin antibody, microtubules fail to regrow into cytoplasmic arrays after depolymerization induced by nocodazole or cold. Furthermore, cells injected immediately before or during mitosis fail to assemble a functional spindle. Thus in vivo gamma-tubulin is required for microtubule nucleation throughout the mammalian cell cycle.     

Interleukin-3 supports growth of mouse pre-B-cell clones in vitro

Study of the differentiation of immunoglobulin-producing B lymphocytes has been hampered by the inability to maintain homogeneous populations of precursor cells in vitro. We describe here that interleukin-3 supports the growth of freshly isolated fetal liver pre-B cells and the long-term culture of interleukin-3 dependent pre-B-cell clones that can be induced to mature into antibody secreting cells in vitro.     

Intranuclear rodlets in retrochiasmatic area neurons of the hypothalamus of the rat

Summary Microfilamentous spindle-shaped nuclear rodlets are described in neurons of the retrochiasmatic area in the rat hypothalamus. The authors consider these structures as normal and dynamic nuclear inclusions of these neurons, although their significance remains unknown.     

Distribution of histamine in 7 brain regions in different species and strains of mammals

Resumen En las especies estudiadas el hipotálamo es la región mas rica en histamina (HT). En la rata, la mayor proporción de HT se localiza en el sedimento de los homogenizados en medio isotónico centrifugados a 10⁵×g; la proporción de HT en el sedimento varia ampliamente de una región a otra.