Distribution of the enantiomers of hydroxychloroquine and its metabolites in ocular tissues of the rabbit after oral administration of racemic-hydroxychloroquine

The disposition of the enantiomers of hydroxychloroquine (HCQ) and its major metabolites in ocular tissues of rabbits has been studied. Both albino, New Zealand White (NZW), and pigmented animals were administered daily oral doses of rac-HCQ, (S)-HCQ or (R)-HCQ (20 mg/kg) over 1, 6, or 8 day periods or for 8 days followed by a 7-day washout period. At the end of the study periods, plasma and whole blood samples were collected and the rabbits were sacrificed. The eyes were collected, the aqueous humor removed with a syringe, and the eyes separated into the cornea, lens, vitreous body, iris, choroid-retina, sclera, and conjunctiva. The concentrations of (R)-HCQ, (S)-HCQ, and their respective metabolites were determined using a validated enantioselective liquid chromatographic assay. The data from these studies indicate that HCQ accumulated in both pigmented and nonpigmented ocular tissues. In the pigmented tissues, HCQ and its metabolites were bound to melanin and the binding was not enantiospecific. In the nonpigmented tissues and in the iris and retina-choroid of the NZW rabbits, the accumulation appeared to be the result of a reversible and enantioselective binding of HCQ and its metabolites to an unidentified biopolymer present in these ocular tissues. © 1994 Wiley-liss, Inc.     

Development of media for the mixotrophic/heterotrophic culture ofBrachiomonas submarina

The marine algaBrachiomonas submarina var.pulsifera (Droop) CCAP 7/2A, is employed as a food organism in aquaculture; it can be cultured heterotrophically or mixotrophically. Growth rates and productivity under heterotrophic conditions were lower than those achieved under mixotrophic conditions. By reducing the osmotic potential of the medium, whilst simultaneously increasing the levels of nitrogen and phosphorus and using sodium acetate as a carbon source, a 20-fold increase in final yield was attained. This corresponded to a maximum culture of 9.02times 10⁶ cells ml^–1 and a dry weight of 2.51 g l^–1.Author for correspondence     

Algae as indicators of environmental change

Despite an increased awareness by governments and the general public of the need for protecting all types of aquatic habitats, human impacts continue to impair the services that these ecosystems provide. Increased monitoring activities that locus on all major biological compartments are needed to quantify the present condition of Earth's aquatic resources and to evaluate the effectiveness of regulations designed to rehabilitate damaged ecosystems. Algae are an ecologically important group in most aquatic ecosystems but are often ignored as indicators of aquatic ecosystem change. We attribute this situation both to an underappreciation of the utility of algal indicators among non-phycologists and to a lack of standardized methods for monitoring with algae.Because of their nutritional needs and their position at the base of aquatic foodwebs, algal indicators provide relatively unique information concerning ecosystem condition compared with commonly used animal indicators. Algae respond rapidly and predictably to a wide range of pollutants and, thus, provide potentially useful early warning signals of deteriorating conditions and the possible causes. Algal assemblages provide one of the few benchmarks for establishing historical water quality conditions and for characterizing the minimally impacted biological condition of many disturbed ecosystems. Preliminary comparisons suggest that algal indicators are a cost-effective monitoring tool as well.Based on available evidence from field studies, we recommend development of taxonomic indicators based on diatoms (Bacillariophyceae) as a standardized protocol for monitoring ecosystem change. Both population- and community-level indices have inherent strengths, and limitations and information from both levels of biological organization should be utilized in tandem. However, further information concerning species tolerances to a variety of anthropogenic stressors is needed if autecological indices are to be used routinely for monitoring purposes. While functional measures (e.g. productivity) may also prove useful as monitoring tools, further investigation is required to characterize the reliability of alternative methodologies and to assess the consistency of these indicators under varying field conditions.Author for correspondence     

Optimization and maintenance of soluble methane monooxygenase activity inMethylosinus trichosporium OB3b

Soluble methane monooxygenase (sMMO) maximization studies were carried out as part of a larger effort directed towards the development and optimization of an aqueous phase, multistage, membrane bioreactor system for treatment of polluted groundwater. A modified version of the naphthalene oxidation assay was utilized to determine the effects of methane:oxygen ratio, nutrient supply, and supplementary carbon sources on maximizing and maintaining sMMO activity inMethylosinus trichosporium OB3b.Methylosinus trichosporium OB3b attained peak sMMO activity (275–300 nmol of naphthol formed h^–1 mg of protein^–1 at 25°C) in early stationary growth phase when grown in nitrate mineral salts (NMS) medium. With the onset of methane limitation however, sMMO activity rapidly declined. It was possible to define a simplified nitrate mineral salts (NMS) medium, containing nitrate, phosphate and a source of iron and magnesium, which allowed reasonably high growth rates (_max 0.08 h^–1) and growth yields (0.4–0.5 g cells/g CH₄) and near maximal activities of sMMO. In long term batch culture incubations sMMO activity reached a stable plateau at approximately 45–50% of the initial peak level and this was maintained over several weeks. The addition of d-biotin, pyridoxine, and vitamin B₁₂ (cyanocobalamin) increased the activity level of sMMO in actively growing methanotrophs by 25–75%. The addition of these growth factors to the simplified NMS medium was found to increase the plateau sMMO level in long term batch cultures up to 70% of the original peak activity.Abbreviations sMMO soluble methane monooxygenase - pMMO particulate methane monooxygenase - NMS nitrate mineral salts - TCE trichloroethene - NADH reduced nicotinamide adenine dinucleotide     

Guanine nucleotide regulatory protein alterations in young Milan hypertensive strain rats

Vascular smooth muscle cell membranes from prehypertensive rats of the Milan hypertensive strain (MHS) were used to examine adenylyl cyclase activity and its regulation by guanine nucleotide regulatory proteins (G-proteins). Basal adenylyl cyclase activity was similar in MHS and Milan normontensive strain (MNS) membranes. Forsokolin (10^?4 M) produced a significantly greater stimulatory response in MHS membranes, but this was not observed with NaF (10^?2 M). Isoporterenol (10^?4 M) caused a significantly decreased stimulation of adenylyl cyclase activity in MHS membranes, while prostaglandin E₁ (10^?5 M) produced similar responses in the two strains. G_i function and GTP responses, as observed by biphasic effects of GTP on isoproterenol-stimulated membranes, were similar in both strains. The levels of G_i2α and G_qα/G₁₁α were similar in the two strains, while the levels of G_sα (44 and 42 kDa forms) and the β-subunit were significantly reduced by ～20% in MHS membranes. The α-subunit of G_i3 was dramatically reduced by ～80% in MHS membranes. The affinities of β-adrenergic receptors for the antagonist, cyanophindolol, were similar in the two strains; however, the number of β-adrenoceptors was substantially reduced in MHS membranes. These findings may be of relevance to altered vascular reactivity and transmembrane ion distribution observed in the MHS.     

Photosynthetic gas exchange response of poplars to steady-state and dynamic light environments

The steady-state and dynamic photosynthetic response of two poplar species (Populus tremuloides and P. fremontii) to variations in photon flux density (PFD) were observed with a field portable gas exchange system. These poplars were shown to be very shade intolerant with high light saturation (800 to 1300 mol photons m^–2 s^–1) and light compensation (70 to 100 mol m^–2 s^–1) points. Understory poplar leaves showed no physiological acclimation to understory light environments. These plants become photosynthetically induced quickly (10 min). Activation of Rubisco was the primary limitation for induction, with stomatal opening playing only a minor role. Leaves maintained high stomatal conductances and stomata were unresponsive to variations in PFD. Leaves were very efficient at utilizing rapidly fluctuating light environments similar to those naturally occurring in canopies. Post-illumination CO₂ fixation contributed proportionally more to the carbon gain of leaves during short frequent lightflecks than longer less frequent ones. The benefits of a more dynamic understory light environment for the carbon economy of these species are discussed.     

Genetic differentiation in carbon isotope discrimination and gas exchange in Pseudotsuga menziesii

Patterns of genetic variation in gas-exchange physiology were analyzed in a 15-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) plantation that contains 25 populations grown from seed collected from across the natural distribution of the species. Seed was collected from 33°30 to 53°12 north latitude and from 170 m to 2930 m above sea level, and from the coastal and interior (Rocky Mountain) varieties of the species. Carbon isotope discrimination () ranged from 19.70() to 22.43() and was closely related to geographic location of the seed source. The coastal variety (20.50 (SE=0.21)) was not significantly different from the interior variety (20.91 (0.15)). Instead, most variation was found within the interior variety; populations from the southern Rockies had the highest discrimination (21.53 (0.20)) (lowest water-use efficiency). Carbon isotope discrimination (), stomatal conductance to water vapor (g), the ratio of intercellular to ambient CO₂ concentration (c_i/c_a), and intrinsic water-use efficiency (A/g) were all correlated with altitude of origin (r=0.76, 0.73, 0.74, and –0.63 respectively); all were statistically significant at the 0.01 level. The same variables were correlated with both height and diameter at age 15 (all at P0.0005). Observed patterns in the common garden did not conform to our expectation of higher WUE, measured by both A/g and , in trees from the drier habitats of the interior, nor did they agree with published in situ observations of decreasing g and with altitude. The genetic effect opposes the altitudinal one, leading to some degree of homeostasis in physiological characteri tics in situ.     

Size and sex allocation in monoecious woody plants

The female size advantage hypothesis predicts that the allocation ratio of female: male reproductive effort should increase with plant size (total reproductive effort). A male height advantage hypothesis has also been proposed, based on the supposed greater advantage of height to male reproductive success in wind-pollinated plants. These ideas were tested with data for wind-pollinated, monoecious trees and shrubs which exhibit a suitably large range of sizes. Number of male inflorescences increased faster with size than did number of female inflorescences in 2 of 9 species; in the remaining 7 species there was no significant difference. The male:female ratio of inflorescence numbers increased with height in 4 of 7 species and did not change significantly in the remaining 3 species, as shown by regression. Height and size are highly correlated and so their effects could not be distinguished. The fact that many conifers place the female cones uppermost in the crown suggests that size and not height favors increased allocation to male function, as does well-established theory connecting the existence of male versus female size advantage to pollen and seed dispersal chacteristics. Regression analysis of the relation between male and female reproductive effort should be done by reduced major axis regression; ordinary least squares regression underestimates slopes; in this study opposite conclusions could be drawn from ordinary least squares and reduced major axis regressions.     

Sequential variation in the components of reproductive success in the distylousJasminum fruticans (Oleaceae)

A 2-year study of three natural populations of the distylousJasminum fruticans showed that mean fruit and seed production were significantly greater in shortstyled plants (thrums) than in long-styled plants (pins). In this study, we investigated the role of four sequential factors which may differentially influence fruit and seed set in the two floral morphs: (1) differences in flowering phenology, (2) a limitation of pollen transfer towards pins, (3) a differential capacity of the two morphs to act through famale and male function and (4) differential fruit abortion in the two morphs. Fruit set was significantly influenced by differences in flowering phenology although there were no differences in flowering time between the two morphs. supplementary pollinations in a natural population significantly increased fruit set and reduced the difference in fruit set between the two morphs in relation to controls, indicating a limitation on pollen transfer which was most severe towards pin stigmas. In reciprocal crosses, seed set was significantly dependent on the paternal and maternal identity of the pin parent. There was no significant variation among thrums for their performance as male or female parent. Furthermore, individual pin plants with relatively high percentage seed set as female parents gave poor seed set as male parents and vice-versa. Whereas fruit removal had no effect on seed number in thrum plants, a greater proportion of viable seeds were produced on pin plants which were left to naturally mature their fruits than on pins which had fruits artificially removed, suggesting the occurrence of selective fruit abortion in pins but not in thrums. The initially greater maternal fitness of thrums due to their greater success as pollen recipients may thus be opposed by increased viable seed set in the pins due to factors acting after the pollination stage. The relative reproductive success of floral morphs in the distylousJ. fruticans is thus differentially influenced by ecological factors occurring at different stages of the reproductive process.     

Molecular biology, genetics and regulation of nitrite reduction in higher plants

Nitrite reductase (ferredoxin:nitrite oxidoreductase, EC 1.6.6.1) carries out the six-electron reduction of nitrite to ammonium ions in the chloroplasts/plastids of higher plants. The complete or partial nucleotide sequences of a number of nitrite reductase apoprotein genes or cDNAs have been determined. Deduced amino acid sequence comparisons have identified conserved regions, one of which probably is involved in binding the sirohaem/4Fe4S centre and another in binding the electron donor, reduced ferredoxin. The nitrite reductase apoprotein is encoded by the nuclear DNA and is synthesised as a precursor carrying an N-terminal extension, the transit peptide, which acts to target the protein to, and within, the chloroplast/plastid. In those plants examined the number of nitrite reductase apoprotein genes per haploid genome ranges from one (barley, spinach) to four ( Nicotiana tabacum ). Mutants defective in the nitrite reductase apoprotein gene have been isolated in barley. During plastidogenesis in etiolated plants, synthesis of nitrite reductase is regulated by nitrate, light (phytochrome), and an uncharacterised 'plastidic factor' produced by functional chloroplasts. In leaves of green, white-light-grown plants up-regulation of nitrite reductase synthesis is achieved via nitrate and light and down-regulation by a nitrogenous end-product of nitrate assimilation, perhaps glutamine. A role for phytochrome has not been demonstrated in green, light-grown plants. Light regulation of nitrite reductase genes is related more closely to that of photosynthetic genes than to the nitrate reductase gene. In roots of green, white-light-grown plants nitrate alone is able to bring about synthesis of nitrite reductase, suggesting that the root may possess a mechanism that compensates for the light requirement seen in the leaf.