Ultrastructural localization of amiloride-sensitive sodium channels and Na+,K(+)-ATPase in the rat's olfactory epithelial surface

Several studies have indicated that olfactory responses are impeded by amiloride. Therefore, it was of interest to see whether, and if so which, olfactory epithelial cellular compartments have amiloride- sensitive structures. Using ultrastructural methods that involved rapid freezing, freeze-substitution and low temperature embedding of olfactory epithelia, this study shows that, in the rat, this tissue is immunoreactive to antibodies against amiloride sensitive Na(+)- channels. However, microvilli of olfactory supporting cells, as opposed to receptor cilia, contained most of the immunoreactive sites. Apices from which the microvilli sprout and receptor cell dendritic knobs had much less if any of the amiloride-antibody binding sites. Using a direct ligand-binding cytochemical method, this study also confirms earlier ones that showed that olfactory receptor cell cilia have Na+, K(+)-ATPase. It is proposed that supporting cell microvilli and the receptor cilia themselves have mechanisms, different but likely complementary, that participate in regulating the salt concentration around the receptor cell cilia. In this way, both structures help to provide the ambient mucous environment for receptor cells to function properly. This regulation of the salt concentration of an ambient fluid environment is a function that the olfactory epithelium shares with cells of transporting epithelia, such as those of kidney.      

Identifying recorder-induced geographic bias in an Iberian butterfly database

A database with comprehensive butterfly faunistic information from the Iberian Peninsula and the Balearic Islands was used to estimate inventory completeness as well as the environmental, spatial, and land-use effects on sampling intensities, on a 50×50 km UTM grid. The degree of sampling effort was assessed by means of accumulation curves based on the Clench function. Using the General Linear Model regression procedure, the effects of 22 variables on the estimated sampling efforts were assessed. This combination of methods is proposed as a preliminary step in biodiversity studies, in order to evaluate not only the degree of geographic coverage of existing faunistic data, but also the amount and nature of the bias on the faunistic work done throughout the last two centuries. The degree of spatial effects on the data was greater than the effects of environmental or land-use variables, although the latter two proved to be locally relevant. The results confirm previous findings that collecting is often skewed by relatively simple factors that affect collector activity, such as accessibility and attractiveness of sampling sites. With regard to Iberian and Balearic butterflies, adequate inventories on the scale investigated may probably suffice for further studies of the diversity of this insect group. Additionally, the results enabled us to develop general guide lines for the design of further faunistic work in the area.     

Estrogen and progestin effects on urinary calcium and calciotropic hormones in surgically-induced postmenopausal women

Seventeen surgically-induced postmenopausal (PM) women were randomized to receive either 0.625 mg of conjugated estrogens (CE) daily or 150 mg of intramuscular depomedroxyprogesterone acetate (DMPA) every 3 months. Urinary calcium/creatinine ratios were significantly higher than ratios of premenopausal controls before treatment, but were lower in all patients 2 months after both types of treatment. Compared to controls, all PM patients had similar levels of serum PTH and 25 hydroxy vitamin D before and after treatment. As a group, PM patients had lower levels of 1.25-dihydroxyvitamin D. In 5 patients who had levels which were below the normal range, 3 were treated with CE and 2 received DMPA. These patients all had significant increases in 1,25-dihydroxyvitamin D after treatment. Serum calcitonin did not change with either CE or DMPA treatment. These data suggest that, while both CE and DMPA lower calcium excretion in PM women, the mechanism(s) for the effects of hormonal treatment on bone resorption remain unsettled.     

Physiology and kinetics of trimethylamine conversion by two methylotrophic strains in continuous cultivation systems

The change of dilution rate (D) on both Methylophilus methylotrophus NCIMB11348 and Methylobacterium sp. RXM CCMI908 growing in trimethylamine (TMA) chemostat cultures was studied in order to assess their ability to remove odours in fish processing plants. M. methylotrophus NCIMB11348 was grown at dilution rates of 0.012–0.084 h⁻¹ and the biomass level slightly increased up to values of D around 0.07 h⁻¹. The maximum cell production rate was obtained at 0.07 h⁻¹ corresponding to a maximum conversion of carbon into cell mass (35%). The highest rate of TMA consumption was 3.04 mM h⁻¹ occurring at D=0.076 h⁻¹. Methylobacterium sp. RXM CCMI908 was grown under similar conditions. The biomass increased in a more steep manner up to values of D around 0.06 h⁻¹. The maximum cell production rate (0.058 g l⁻¹h⁻¹) was obtained in the region close to 0.06 h⁻¹ where a maximum conversion of the carbon into cell mass (40%) was observed. The maximum TMA consumption was 2.33 mM h⁻¹ at D=0.075 h⁻¹. The flux of carbon from TMA towards cell synthesis and carbon dioxide in both strains indicates that the cell is not excreting products but directing most of the carbon source to growth. Carbon recovery levels of approximately 100% show that the cultures are carbon-limited. Values for theoretical maximum yields and maintenance coefficients are presented along with a kinetic assessment based on the determination of the substrate saturation constant and maximum growth rate for each organism. Received: 25 February 1999 / Received revision: 14 May 1999 / Accepted: 17 May 1999     

Variation in δC values for the seagrass Thalassia testudinum and its relations to mangrove carbon

Carbon isotope ratios (¹³C/¹²C) were measured for the leaves of the seagrass Thalassia testudinum Banks ex König and carbonates of shells collected at the seagrass beds from seven sites along the coast of southern Florida, U.S.A. The δ¹³C values of seagrass leaves ranged from −7.3 to −16.3‰ among different study sites, with a significantly lower mean value for seagrass leaves from those sites near mangrove forests (−12.8 ± 1.1‰) than those far from mangrove forests (−8.3 ± 0.9‰; P < 0.05). Furthermore, seagrass leaves from a shallow water area had significantly lower δ¹³C values than those found in a deep water area (P < 0.01). There was no significant variation in δ¹³C values between young and mature leaves (P = 0.59) or between the tip and base of a leaf blade (P = 0.46). Carbonates of shells also showed a significantly lower mean δ¹³C value in the mangrove areas (−2.3 ± 0.6‰) than in the non-mangrove areas (0.6 ± 0.3‰; P <0.025). In addition, the δ¹³C values of seagrass leaves were significantly correlated with those of shell carbonates (δ¹³C seagrass leaf = −9.1 + 1.3δ¹³C shell carbonate (R² = 0.83, P < 0.01)). These results indicated that the input of carbon dioxide from the mineralization of mangrove detritus caused the variation in carbon isotope ratios of seagrass leaves among different sites in this study.