An application of cineradiography to the study of locomotion in primates

The cineradiographic technique, whereby, at 64 frames/second, the successive positions of every bone segment of animals in motion can be accurately analyzed, was used to study the vertical leap of a Galago alleni from the ground position. This jump, 13 to 14 times the body length of the animal excluding the tail, is a record among primates challenged only by the tarsier. Such vertical leaps from the ground are a common mode of locomotion for the galago. Two different patterns were observed, a symmetrical and an asymmetrical jump. In the former, the two hind limbs move in the same manner and simultaneously; and the propulsive force is equally distributed in both limbs. In the latter (more frequent in our records), the animal shifts its weight onto one foot during the preparatory phase and lifts the other; thus, only one of the hind limbs is responsible for the launching. The angular variations of every knee and ankle articulation and the successive positions of the hind limb bones were measured and diagrammatically analyzed frame by frame. A short film was made to illustrate the cineradiographic technique; it cinematographically and cineradiographically records in successive sequence the galago's leap from the ground. The symmetrical and asymmetrical jumps are also schematically presented.     

The amnesic shellfish poison domoic acid enhances neurotoxicity by excitatory amino acids in cultured neurons

Summary A recent episode of human intoxication by cultured mussels containing a rare excitatory amino acid named domoic acid, received particular attention for its neurological implications. The intoxication produced neurological problems, such as headache, confusion, and loss of memory, particularly severe at times. Neuronal damage was found in the hippocampus and amygdala of four patients. We now report that in neuronal cultures the neurotoxicity of a domoic acid-containing mussel extract is the result of domoic acid potentiation of the excitotoxic effect of glutamic acid and aspartic acid present in high amounts in mussel tissue. Moreover, we show that subtoxic concentrations of domoic acid are sufficient to potentiate glutamic acid and aspartic acid neurotoxicity. We present evidence suggesting that the neurotoxic synergism may be due to a reduction of Mg^{+ +} block at the NMDA receptor-associated channel, following activation of NON-NMDA receptors by domoic acid.     

Protein kinase C from small intestine epithelial cells

Protein kinase C activity has been identified in cytosolic and membrane fractions from rat and rabbit small intestine epithelial cells. The cytosolic fraction comprised about the 75% of total activity. Protein kinase C activity was resolved from other protein kinase activities by ion exchange chromatography. Phosphatidylserine or phosphatidylinositol were required for protein kinase C to be active. In addition, the activity was enhanced by the presence of a diacylglycerol. Diolein and dimyristin were the most effective (13-14 fold activation). In the presence of phosphatidylserine and diolein, the Ka for activation by Ca2+ was 10(-7)M. The phorbol ester TPA substituted for diacylglycerol in activating protein kinase C. Brush border and basolateral membranes contained protein kinase C activity, although the specific activity of the basal lateral membranes was four-fold higher than the specific activity of the brush border membranes. The presence of PKC in small intestine epithelial cells might have important implications in the Ca2+ mediated control of ionic transport in this tissue.     

Combined technique of immunohistochemistry and autoradiography for the simultaneous detection of steroid hormone receptors and their ligand

A combined technique of immunohistochemistry and autoradiography was applied to detect progesterone target cells in tissue sections. The radioactively labeled progestin [3H]-Organon 2058 and the progesterone receptor, revealed by antibodies to the receptor molecule, were localized simultaneously in identical cells on the same tissue section. Technical details that make possible combined detection of the nuclear antigen, present in very small amounts, simultaneously with its steroid ligand are described.     

Morphofunctional study of the digging system of the Namib Desert Golden mole (Eremitalpa granti namibensis): cinefluorographical and anatomical analysis

Digging locomotion of Namib Golden moles has been studied by making X–ray cinematograph films, and the morphology of their locomotor system investigated by means of radiographs and dissections. Biomechanical interpretations of the data so obtained show that moving forwards results from a cyclical compacting and decompacting of the surrounding sand. The whole step–cycle IS made up of a buttressing phase followed by several digging propulsion phases.     

Widespread formation of intracellular calcium carbonates by the bloom-forming cyanobacterium Microcystis

The formation of intracellular amorphous calcium carbonates (iACC) has been recently observed in a few cultured strains of Microcystis, a potentially toxic bloom-forming cyanobacterium found worldwide in freshwater ecosystems. If iACC-forming Microcystis are abundant within blooms, they may represent a significant amount of particulate Ca. Here, we investigate the significance of iACC biomineralization by Microcystis. First, the presence of iACC-forming Microcystis cells has been detected in several eutrophic lakes, indicating that this phenomenon occurs under environmental conditions. Second, some genotypic (presence/absence of ccyA, a marker gene of iACC biomineralization) and phenotypic (presence/absence of iACC) diversity have been detected within a collection of strains isolated from one single lake. This illustrates that this trait is frequent but also variable within Microcystis even at a single locality. Finally, one-third of publicly available genomes of Microcystis were shown to contain the ccyA gene, revealing a wide geographic and phylogenetic distribution within the genus. Overall, the present work shows that the formation of iACC by Microcystis is common under environmental conditions. While its biological function remains undetermined, this process should be further considered regarding the biology of Microcystis and implications on the Ca geochemical cycle in freshwater environments.     

Nuclear localization of two steroid receptor-associated proteins, hsp90 and p59

It has been proposed that the unliganded nontransformed form of steroid hormone receptor is a heterooligomer comprising, in addition to the hormone-binding subunit, two associated proteins: a heat shock protein of MW 90,000 (hsp90) and another protein of MW 59,000 (p59). Using monoclonal antibodies, we demonstrate immunocytochemically the presence of both hsp90 and p59 in cell nuclei of progesterone target cells of the rabbit uterus. While steroid receptors (e.g., progesterone receptors) appear to be exclusively nuclear, we find p59 predominantly in the cell nuclei and hsp90 in both the nucleus and the cytoplasm. In addition, Western blotting of high-salt extracts of nuclear proteins detects the presence of hsp90 and p59 in the nuclei of rabbit uterus. These observations are consistent with the presence of the untransformed heterooligomeric form of steroid hormone receptors in the nuclei of target cells.