Human sperm surface mapping with lectins.

Ten fluorescein isothiocyanate (FITC)-linked lectins [Bauhimia purpurea, Concanavalin A, Dolichos biflorus (DBA), Griffonia simplicifolia I, Griffonia simplicifolia II, Maclura pomifera, Arachis hypogea (PNA), Glycine max, Ulex europaeus (UEA) and Triticum vulgaris agglutinin] have been used to study their binding features on the human ejaculate spermatozoa. Qualitative changes in the labeling pattern have been observed in unfixed and acetone-treated spermatozoa. Furthermore, ultrastructural localization of some of the colloidal gold-linked lectins, namely PNA, UEA and DBA, has been attempted to delineate the binding domains of the specific sugars on the sperm surface. It needs to be emphasized that flow-cytometric methods employed in our study, which provide quantitative slant to qualitative data, should be utilized to evaluate the functional status of the spermatozoa.     

Membranous tubes in pseudoscorpion spermiogenesis

The highly complicated differentiation of the spermatid in the pseudoscorpion Diplotemnus sp. is accomplished without the presence of microtubules. Instead membranous tubes measuring approximately 50 nm in diameter and closely associated with endoplasmic reticulum are found from early to mid spermatids. The lumen of the tube is devoid of electron dense contents but a fluffy material is attached to the cytoplasmic side. They run straight or slightly bent and are in open connection with the cell membrane. First appearing near the cell bridge of the interconnected spermatids they form a bundle in the longitudinal axis during a transitory phase of elongation. When the cell rounds off again the tubules together with the endoplasmic reticulum disappear. The arrangement of the tubes and their presence during abortive elongation of the spermatid suggest a supportive function commonly attributed to microtubules. Moreover, the open connection with the cell membrane and their close association with the endoplasmic reticulum may indicate their participation also in transport.     

Myofibroblasts in human palatal mucosa

Myofibroblasts in human osseous palatal mucosa are described. They appear as fusiform or ramified cells, rich in homogeneous 60- to 70-Angstr?m-thick microfilaments, rough endoplasmic reticulum cisternae, and abundant pinocytotic vesicles in relation with the plasma membrane. On the surface of these cells there are small areas covered by basal lamina. Contacts between myofibroblast processes and other tissue elements are described. Small clusters of oxytalan fibers appear in the vicinity of these cells.     

Extraction of non-timber forest products in the Forests of Biligiri Rangan Hills,India. 3. Productivity,extraction and prospects of sustainable harvest of amla phyllanthus emblica, (Euphorbiaceae)

Sustainable extraction of non-timber forest products (NTFPs) depends upon harvesting a small fraction of the total productivity. Over-exploitation can lead to a loss of biodiversity, but a low level of extraction, without value addition at the point of origin, is usually not economically feasible for extractors. Extraction and productivity levels per unit area for most non-timber forest products are unknown, nor do we have much information about value addition at various points in the marketing channels. Here we determine extraction and productivity levels for Amla trees (Phyllanthus emblica), which yield fruits that are used for a wide variety of purposes in preparation of various foods, beverages and medicines. We also present preliminary data on the price appreciation of the fruit for one of the processed products. We have determined that the current level of extraction, 60-80% of all fruits at the population level, may have a negative effect on new recruitment. We present a model for value addition that has the potential to enhance income and reduce the level of extraction. This model is currently being implemented by the Soliga community with the assistance of a non-governmental organization.     

Population genetics of Cordia alliodora (Boraginaceae), a neotropical tree. 1. Genetic variation in natural populations

We provide an estimate of genetic differentiation within and among 11 populations of Cordia alliodora, an economically important timber tree Cordia alliodora is a widespread species that is distributed throughout Central and South America. Our survey of isozyme variation was conducted on material gathered for international provenance trials over approximately 1,000 km in Central America. Results from provenance trials indicate that there are significant differences between Atlantic and Pacific coast provenances for quantitative characters. Genetic data support some of these findings. Populations of C. alliodora show significant differences in allele frequency at various loci. Significant differences in multilocus allele frequencies occur at 13 of the 55 possible combinations. Eight of these 13 populations are situated on opposite coasts. This physical separation corresponds well with the results of provenance trials that indicate differentiation among the Atlantic and Pacific populations in quantitative morphological traits. We also found a significant negative correlation between levels of heterozygosity and the amount of rainfall, indicating that populations from the drier zone are genetically more heterogenous than populations from the wet zone. Our study indicates that in situ and ex situ conservation should accord high priority to the dry zone populations; furthermore, conservation of this widespread species would require preservation of multiple populations.     

Population genetics of Cordia alliodora (Boraginaceae), a neotropical tree. 2. Mating system

A multilocus mixed mating model was used to evaluate the mating system of a natural population of Cordia alliodora (Boraginaceae), a neotropical tree. The population was highly outcrossed (t_m = 0.966 ± 0.027), in agreement with results from controlled crosses. Departures from the mixed mating model were evident, suggesting some nonrandom, correlated mating. Pollen pool heterogeneity and variation in estimates of individual outcrossing rates indicated that the population may be genetically substructured. Individual outcrossing rates obtained for the samples taken from within different parts of the same tree indicated reduced levels of outcrossing due to limited sampling of the pollen pool. The incompatibility mechanism in C. alliodora, combined with variation in flowering and stand density, appears to lead to both temporal and spatial substructuring of the population.     

Microglial cells in the central nervous system of the rabbit and rat: cytochemical identification using two different lectins

Microglial cells were selectively demonstrated in the central nervous system of adult rabbits and rats using lectin histochemistry. Biotinylated Ricinus communis agglutinin-120 (RCA-1) and biotinylated Griffonia simplicifolia B4 isolectin (GSA I-B4) were used as histochemical markers on sections of Bouin-fixed paraffin-embedded cerebrum and cerebellum. Results were quite similar using both lectins and both species. GSA I-B4 resulted in a better staining in the rat, while RCA-1 labelling was superior in the rabbit. Neither neurons nor glial cells other than microglia were stained with our technique. Lectin histochemistry applied for the detection of microglial cells appears to be of sufficient selectivity and may be considered as an important tool in the morphological and neurobiological study of these cells.     

Spinal reflexes as a basis for tremor in the premammillary cat.

A maintained tremor observed in premammillary cats has been studied by varying the load attached to the soleus muscle, by electrical recording, and stimulation. The frequency and amplitude of the tremor varies widely with changes in elastic or inertial loading (springs or flywheels). These variations agree well with predictions based on the idea that the tremor is maintained by relfexes reinforcing a tendency for oscillation in a mass-spring system (which includes the elasticity of the muscle). Spinal stretch reflexes are probably responsible since a relatively fixed delay of 8.5 +/- 2.9 ms is observed between the peaks of recorded afferent and electromyographic activity. Stimulation of the lateral gastrocnemius--soleus nerve completely resets the tremor, again suggesting a reflex origin.     

An orthoquinone isolated from Salvia aethiopis

A new orthonaphthoquinone diterpene has been isolated from Salvia aethiopis and given the trivial name aethiopinone. The structure of this natural     

Evolution of the pineal gland in the adult chicken.

The structural pattern of the pineal gland in the hen corresponds to a more advanced stage of the evolution which began in an early period of the animal's life. This evolution corresponds mainly to the transformation of the large follicular cavities into cellular 'rosettes'. The parafollicular layer disappears from the rosette wall which thus remains with only one row of cells (A and B pinealocytes). The cellular hypertrophy and the great development of the pinealocyte organelles in the adult pineal gland makes us think of this gland as a functionally active organ. This functional activity must have remained during the entire period of the time studied (1--5 years), due to the ultrastructural uniformity found and due to the fact that we could not observe any type of degenerative process in the gland.