The Diversity of Coral Reefs: What Are We Missing?

Tropical reefs shelter one quarter to one third of all marine species but one third of the coral species that construct reefs are now at risk of extinction. Because traditional methods for assessing reef diversity are extremely time consuming, taxonomic expertise for many groups is lacking, and marine organisms are thought to be less vulnerable to extinction, most discussions of reef conservation focus on maintenance of ecosystem services rather than biodiversity loss. In this study involving the three major oceans with reef growth, we provide new biodiversity estimates based on quantitative sampling and DNA barcoding. We focus on crustaceans, which are the second most diverse group of marine metazoans. We show exceptionally high numbers of crustacean species associated with coral reefs relative to sampling effort (525 species from a combined, globally distributed sample area of 6.3 m(2)). The high prevalence of rare species (38% encountered only once), the low level of spatial overlap (81% found in only one locality) and the biogeographic patterns of diversity detected (Indo-West Pacific>Central Pacific>Caribbean) are consistent with results from traditional survey methods, making this approach a reliable and efficient method for assessing and monitoring biodiversity. The finding of such large numbers of species in a small total area suggests that coral reef diversity is seriously under-detected using traditional survey methods, and by implication, underestimated.     

Inhibition of energy-transducing functions of chloroplast membranes by lipophilic iron chelators

Lipophilic metal chelators inhibit various energy-transducing functions of chloroplasts. The following observations were made.1. Photophosphorylation coupled to any known mode of electron transfer, i.e. whole-chain noncyclic, the partial noncyclic Photosystem I or Photosystem II reactions, or cyclic, is inhibited by several lipophilic chelators, but not by hydrophilic chelators.2. The light- and dithioerythritol-dependent Mg²⁺-ATPase was also inhibited by the lipophilic chelators.3. Electron transport through either partial reaction, Photosystem I or Photosystem II was not inhibited by lipophilic chelators. Whole-chain coupled electron transport was inhibited by bathophenanthroline, and the inhibition was not reversed by uncouplers. The diketone chelators diphenyl propanedione and nonanedione inhibited the coupled, whole-chain electron transport and the inhibition was reversed by uncouplers, a pattern typical of energy transfer inhibitors.The electron transport inhibition site is localized in the region of plastoquinone → cytochrome f. This inhibition site is consistent with other recent work (Prince et al. (1975) FEBS Lett. 51, 108 and Malkin and Aparicio (1975) Biochem. Biophys. Res. Commun. 63, 1157) showing that a non-heme iron protein is present in chloroplasts having a redox potential near +290 mV. A likely position for such a component to function in electron transport would be between plastoquinone and cytochrome f, just where our data suggests there to be a functional metalloprotein.4. Some of the lipophilic chelators induce H⁺ leakiness in the chloroplast membrane, making interpretation of their phosphorylation inhibition difficult. However, 1–3 mM nonanedione does not induce significant H⁺ leakiness, while inhibiting ATP formation and the Mg²⁺-ATPase. Nonanedione, at those concentrations, causes a two- to four-fold increase in the extent of H⁺ uptake.5. These results are consistent with, but do not prove, the involvement of a non-heme iron or a metalloprotein in chloroplast energy transduction.     

Isolation of sulfate‐reducing bacteria from deep sediment layers of the pacific ocean

Bacterial populations exist at great depths in marine sediments, but little is known about the type and characteristics of organisms in this unique bacterial environment. Cascadia Margin sediments from the Pacific Ocean have deep bacterial activity and bacterial populations, which are stimulated around a gas hydrate zone (215–225 m below sea floor [mbsf]). Bacterial sulfate reduction is the dominant anaerobic process within these sediments, and the depth distribution of sulfate‐reducing activity corresponds with distributions of viable sulfate‐reducing bacteria (SRB). Anaerobically stored sediments from this site were used to isolate sulfate‐reducing bacteria using a temperature‐gradient system, elevated pressure and temperatures, different media, and a range of growth substrates. A variety of enrichments on lactate were obtained from 0.5 and 222 mbsf, with surprisingly more rapid growth from the deeper sediments. The temperature range of enrichments producing strong growth from 222 mbsf was markedly wider than those from the near surface sediment (15–45°C and 9–19°C, respectively). This presumably reflects a temperature increase in deeper sediments. Only a few of these enrichments were successfully isolated due to very slow or no growth on subculture, despite the use of a wide range of different media and growth conditions. Psychrophilic and mesophilic sulfate‐reducing isolates were obtained from 0.5 m depth. As the minimum growth temperature of the mesophile (probably a Desulfotomaculum sp.) was above the in situ temperature of 3°C, it must have been present in the sediment as spores. A larger number of isolates (23) was obtained from 222 mbsf, and these barophilic SRB were closely related (based on 16S rRNA gene analysis), but not identical to, Desulfovibrio profundus, recently isolated from deep sediments from the Japan Sea. Bacteria related to D. profundus may be widespread in deep marine sediments.     

Toxicity of cadmium and zinc mixtures to the decaudized cercarial life span of Diplostomum spathaceum

The effects of cadmium and zinc mixtures at concentrations ranging from 0.1 to 10,000 microg l(-1) on the life-span of decaudized cercarial bodies (cercariae that have shed their tails) of Diplostomum spathaceum (Trematoda: Diplostomatidae) was investigated. Cercariae were exposed to metal mixtures of equal and unequal concentrations, and a low-dose pre-treatment followed by a high-dose exposure mixtures. Metal mixtures demonstrated variable effects on decaudized cercariae either by increasing or reducing their life-span compared to single metal exposures dependent on concentration and the type of mixed metal treatment. Prolonged exposure to equal metal mixtures at low concentrations (0.1-100 microg l(-1)) resulted in a reduction in the life-span of decaudized cercariae at 0.1 and 100 microg l(-1) in those individuals decaudized during the initial 24 h exposure period compared with those decaudized during the final 24 h period of cercarial survival, whilst in controls there was no significant life-span change between the two time periods. Decaudized cercariae which were exposed to low concentrations (0.1-100 microg l(-1)) of equal metal mixtures were also evaluated for their role as an indicator of larval 'fitness' for migrating through the tissues of their target fish host for those individuals decaudized during the initial 24 h exposure period, and demonstrated only a limited change in their life-span compared to control and single metal exposures. The importance of metal mixtures in parasite establishment in the fish host is discussed.     

Differential effects of interleukin-7 and interleukin-15 on NK cell anti-human immunodeficiency virus activity

The ability of interleukin-7 (IL-7) and IL-15 to expand and/or augment effector cell functions may be of therapeutic benefit to human immunodeficiency virus (HIV)-infected patients. The functional effects of these cytokines on innate HIV-specific immunity and their impact on cells harboring HIV are unknown. We demonstrate that both IL-7 and IL-15 augment natural killer (NK) function by using cells (CD3(-) CD16(+) CD56(+)) from both HIV-positive and -negative donors. Whereas IL-7 enhances NK function through upregulation of Fas ligand, the effect of IL-15 is mediated through upregulation of tumor necrosis factor-related apoptosis-inducing ligand. The difference in these effector mechanisms is reflected by the ability of IL-15-treated but not IL-7-treated NK cells to reduce the burden of replication-competent HIV in autologous peripheral blood mononuclear cells (PBMC) (infectious units per million for control NK cells, 6.79; for IL-7-treated NK cells, 236.17; for IL-15-treated cells, 1.01; P = 0.01 versus control). In addition, the treatment of PBMC with IL-15-treated but not IL-7-treated NK cells causes undetectable HIV p24 (five of five cases), HIV RNA (five of five cases), or HIV DNA (three of five cases). These results support the concept of adjuvant immunotherapy of HIV infection with either IL-7 or IL-15 but suggest that the NK-mediated antiviral effect of IL-15 may be superior.     

Citrate oscillates in liver and pancreatic beta cell mitochondria and in INS-1 insulinoma cells

Oscillations in citric acid cycle intermediates have never been previously reported in any type of cell. Here we show that adding pyruvate to isolated mitochondria from liver, pancreatic islets, and INS-1 insulinoma cells or adding glucose to intact INS-1 cells causes sustained oscillations in citrate levels. Other citric acid cycle intermediates measured either did not oscillate or possibly oscillated with a low amplitude. In INS-1 mitochondria citrate oscillations are in phase with NAD(P) oscillations, and in intact INS-1 cells citrate oscillations parallel oscillations in ATP, suggesting that these processes are co-regulated. Oscillations have been extensively studied in the pancreatic beta cell where oscillations in glycolysis, NAD(P)/NAD(P)H and ATP/ADP ratios, plasma membrane electrical activity, calcium levels, and insulin secretion have been well documented. Because the mitochondrion is the major site of ATP synthesis and NADH oxidation and the only site of citrate synthesis, mitochondria need to be synchronized for these factors to oscillate. In suspensions of mitochondria from various organs, most of the citrate is exported from the mitochondria. In addition, citrate inhibits its own synthesis. We propose that this enables citrate itself to act as one of the cellular messengers that synchronizes mitochondria. Furthermore, because citrate is a potent inhibitor of the glycolytic enzyme phosphofructokinase, the pacemaker of glycolytic oscillations, citrate may act as a metabolic link between mitochondria and glycolysis. Citrate oscillations may coordinate oscillations in mitochondrial energy production and anaplerosis with glycolytic oscillations, which in the beta cell are known to parallel oscillations in insulin secretion.     

Comparative Studies on Plastoquinones: V. Changes in Lipophilic Chloroplast Quinones during Development

Changes of lipophilic chloroplast quinones in corn, oats, peas, and Vicia faba are reported after 0, 4, 8, 12, 16, 20, 24, 48, 72, or 96 hours of exposure to light. There is a pronounced increase in plastoquinone A and chlorophyll levels and slight increase, in plastoquinone C_1-6, vitamin K₁, and α-tocopherylquinone content. Coenzyme Q levels, on the other hand, show little change upon exposure to light.