1,499 research outputs found
Kindia (Pavetteae, Rubiaceae), a new cliff-dwelling genus with chemically profiled colleter exudate from Mt Gangan, Republic of Guinea
A new genus Kindia (Pavetteae, Rubiaceae) is described with a single species, Kindia gangan, based on collections made in 2016 during botanical exploration of Mt Gangan, Kindia, Republic of Guinea in West Africa. The Mt Gangan area is known for its many endemic species including the only native non-neotropical Bromeliaceae Pitcairnia feliciana. Kindia is the fourth endemic vascular plant genus to be described from Guinea. Based on chloroplast sequence data, the genus is part of Clade II of tribe Pavetteae. In this clade, it is sister to Leptactina sensu lato (including Coleactina and Dictyandra). K. gangan is distinguished from Leptactina s.l. by the combination of the following characters: its epilithic habit; several-flowered axillary inflorescences; distinct calyx tube as long as the lobes; a infundibular-campanulate corolla tube with narrow proximal section widening abruptly to the broad distal section; presence of a dense hair band near base of the corolla tube; anthers and style deeply included, reaching about mid-height of the corolla tube; anthers lacking connective appendages and with sub-basal insertion; pollen type 1; pollen presenter (style head) winged and glabrous (smooth and usually hairy in Leptactina); orange colleters producing a vivid red exudate, which encircle the hypanthium, and occur inside the calyx and stipules. Kindia is a subshrub that appears restricted to bare, vertical rock faces of sandstone. Fruit dispersal and pollination by bats is postulated. Here, it is assessed as Endangered EN D1 using the 2012 IUCN standard. High resolution LC-MS/MS analysis revealed over 40 triterpenoid compounds in the colleter exudate, including those assigned to the cycloartane class. Triterpenoids are of interest for their diverse chemical structures, varied biological activities, and potential therapeutic value
Diets of Invasive Channel Catfish are Subsidized by Invasive Riparian Trees
Russian olive (Elaeagnus angustifolia) is an invasive, fruit- bearing riparian tree that dominates riparian zones of the San Juan River in the southwestern United States. Previous research in this river suggests olive fruit is common in diets of invasive channel catfish (Ictalurus punctatus), but its energetic importance is unknown (i.e. critical for catfish fitness vs. incidental consumption). We assessed Russian olive consumption in channel catfish diets bimonthly for 1 year, hypothesizing that olive consumption would be greatest during periods of high olive availability and low benthic aquatic invertebrate availability. We found that catfish consumed olive fruit throughout the year and that olive comprised up to 44% of total stomach contents by mass, with peaks in spring and fall. Regression models revealed the presence and mass of olive fruit in catfish stomachs were positively associated with catfish total length, with a significant interaction between water temperature and river discharge. Catfish were more likely to consume olive fruit during higher flows, regardless of temperature and at low discharge with higher temperature. Contrary to our hypothesis, neither olive nor benthic invertebrate availability were associated with olive presence in channel catfish diets. Nutrition analysis indicated that olive alone was a low-quality diet item but has the potential to provide a reliable energy source. We used seasonal data to estimate the energetic contribution of olive fruit to catfish populations using a bioen-ergetic model, which estimated that olive fruit accounted for 35.6% of energy (Joules) consumed by catfish populations and satisfied 38% of their metabolic demand. Our results suggest that Russian olive fruit is a significant subsidy to channel catfish in the San Juan River. However, more research is needed to determine the indirect effects of this interaction on native fishes and ecosystem function
Calcium transients in single adrenal chromaffin cells detected with aequorin
AbstractThe effect of 55 mM K+ and nicotine on intracellular free calcium was monitored in bovine adrenal chromaffin cells microinjected with aequorin. In contrast to results with quin 2, which suggested that stimulation of chromaffin cells resulted in sustained rises in free calcium, aequorin measurements showed that 55 mM K+ and nicotine resulted in a transient (60–90 s) elevation of free calcium. The peak free calcium and duration of the transient elicited by nicotine were dose-dependent. The concentration of nicotine (10 μM) giving a maximal secretory response gave a peak rise in free calcium of up to 1 μM. 55 mM K+ which only releases 30% of the catecholamine released by 10 μM nicotine generated a calcium transient indistinguishable from that due to 10 μM nicotine. These results support the idea that nicotinic agonists generate an alternative second messenger in addition to the rise in free calcium
Prevalence of asthma and asthma action plans in South Australia: population surveys from 1990 to 2001
The document attached has been archived with permission from the editor of the Medical Journal of Australia. An external link to the publisher’s copy is included.OBJECTIVES: To assess trends in the prevalence of self-reported doctor-diagnosed asthma, associated asthma related morbidity, and the uptake of written asthma action plans in South Australia, 1990–2001. DESIGN, SETTING AND PARTICIPANTS: Surveys by telephone interview of the South Australian population between 1990 and 2001, and interview of participants in their own homes by trained health interviewers. MAIN OUTCOME MEASURES: Asthma prevalence, percentage of patients with written action plans, and asthma associated morbidity. RESULTS: The reported prevalence of doctor-diagnosed asthma has increased from 8% (95% CI, 6.4%–9.6%) in 1990 to 12.8% (95% CI, 11.4%–14.2%) in 2001. Morbidity, as measured by wakening at night (daily or weekly) and days lost from normal activities because of asthma, has remained constant over the decade. The percentage of patients with written asthma action plans increased to a peak of 42.3% (95% CI, 40.3%–44.3%) in 1995, but then declined to 22.2% (95% CI, 20.7%–23.7%) in 2001. CONCLUSIONS: The prevalence of asthma has increased while morbidity has remained constant, indicating that the burden of asthma has increased. The associated decline in the percentage of patients with asthma action plans in recent years is cause for concern.David H Wilson, Robert J Adams, Sarah L Appleton, Graeme Hugo, David Wilkinson, Janet Hiller, Philip Ryan, Julianne Cheek and Richard E Ruffi
Kupeantha (Coffeeae, Rubiaceae), a new genus from Cameroon and Equatorial Guinea
Two new coffee relatives (tribe Coffeeae, Rubiaceae), discovered during botanical expeditions to Cameroon, are examined for generic placement, and the placement of three previously known species (Argocoffeopsis fosimondi, A. spathulata and Calycosiphonia pentamera) is reinvestigated using plastid sequence (accD-psa1, rpl16, trnL-F) and morphological data. Seed biochemistry of the new species and pollen micromorphology (only one of the two species) are also studied. Based on the plastid sequence data, the new taxa are nested in a wellsupported monophyletic group that includes Argocoffeopsis and Calycosiphonia. Within this clade, three well-supported subclades are recovered that are morphologically easy to diagnose: (1) Calycosiphonia (excluding C. pentamera), (2) Argocoffeopsis (excluding A. fosimondi and A. spathulata), and (3) a clade including the above excluded species, in addition to the new species. Based on the results, Kupeantha, a new genus of five species, is described, including two new Critically Endangered taxa from the Highlands of Cameroon: Kupeantha ebo and K. kupensis. Phytochemical analysis of Kupeantha seeds reveals compounds assigned as hydroxycinnamic acid derivatives, amino acids and ent-kaurane diterpenoids; caffeine was not detected. Kupeantha is the first new genus described in tribe Coffeeae in 40 years
Effects of Long-Term Hypoxia on Enzymes of Carbohydrate Metabolism in the Gulf killifish, Fundulus grandis
The goal of the current study was to generate a comprehensive, multi-tissue perspective of the effects of chronic hypoxic exposure on carbohydrate metabolism in the Gulf killifish Fundulus grandis. Fish were held at approximately 1.3·mg·l–1 dissolved oxygen (~3.6·kPa) for 4·weeks, after which maximal activities were measured for all glycolytic enzymes in four tissues (white skeletal muscle, liver, heart and brain), as well as for enzymes of glycogen metabolism (in muscle and liver) and gluconeogenesis (in liver). The specific activities of enzymes of glycolysis and glycogen metabolism were strongly suppressed by hypoxia in white skeletal muscle, which may reflect decreased energy demand in this tissue during chronic hypoxia. In contrast, several enzyme specific activities were higher in liver tissue after hypoxic exposure, suggesting increased capacity for carbohydrate metabolism. Hypoxic exposure affected fewer enzymes in heart and brain than in skeletal muscle and liver, and the changes were smaller in magnitude, perhaps due to preferential perfusion of heart and brain during hypoxia. The specific activities of some gluconeogenic enzymes increased in liver during long-term hypoxic exposure, which may be coupled to increased protein catabolism in skeletal muscle. These results demonstrate that when intact fish are subjected to prolonged hypoxia, enzyme activities respond in a tissue-specific fashion reflecting the balance of energetic demands, metabolic role and oxygen supply of particular tissues. Furthermore, within glycolysis, the effects of hypoxia varied among enzymes, rather than being uniformly distributed among pathway enzymes
Control of breathing and respiratory gas exchange in high-altitude ducks native to the Andes
We examined the control of breathing and respiratory gas exchange in six species of high-altitude duck that independently colonized the high Andes. We compared ducks from high-altitude populations in Peru (Lake Titicaca at ∼3800 m above sea level; Chancay River at ∼3000–4100 m) with closely related populations or species from low altitude. Hypoxic ventilatory responses were measured shortly after capture at the native altitude. In general, ducks responded to acute hypoxia with robust increases in total ventilation and pulmonary O2 extraction. O2 consumption rates were maintained or increased slightly in acute hypoxia, despite ∼1–2°C reductions in body temperature in most species. Two high-altitude taxa – yellow-billed pintail and torrent duck – exhibited higher total ventilation than their low-altitude counterparts, and yellow-billed pintail exhibited greater increases in pulmonary O2 extraction in severe hypoxia. In contrast, three other high-altitude taxa – Andean ruddy duck, Andean cinnamon teal and speckled teal – had similar or slightly reduced total ventilation and pulmonary O2 extraction compared with low-altitude relatives. Arterial O2 saturation (SaO2) was elevated in yellow-billed pintails at moderate levels of hypoxia, but there were no differences in SaO2 in other high-altitude taxa compared with their close relatives. This finding suggests that improvements in SaO2 in hypoxia can require increases in both breathing and haemoglobin–O2 affinity, because the yellow-billed pintail was the only high-altitude duck with concurrent increases in both traits compared with its low-altitude relative. Overall, our results suggest that distinct physiological strategies for coping with hypoxia can exist across different high-altitude lineages, even among those inhabiting very similar high-altitude habitats
Systems Integration and Test of the Lunar Flashlight Spacecraft
Lunar Flashlight is a 6U CubeSat launching in late 2022 or early 2023 that will search for surface water ice content in permanently shadowed regions at the south pole of the Moon using infrared relative reflectance spectroscopy. The mission will act as a technology demonstration of an Advanced Spacecraft Energetic NonToxic (ASCENT) green propulsion system and active laser spectroscopy within the CubeSat form-factor. This paper provides an overview of the entire Systems Integration and Test campaign which took place at the Jet Propulsion Laboratory and the Georgia Institute of Technology. From initial testing of the isolated avionics and payload subsystems to the final tests with a fully integrated spacecraft, the project’s integration and test campaign is reviewed, with a focus on lessons learned
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