Energy Transducing Roles of Antiporter-like Subunits in Escherichia coli NDH-1 with Main Focus on Subunit NuoN (ND2)

The proton-translocating NADH-quinone oxidoreductase (complex I/NDH-1) contains a peripheral and a membrane domain. Three antiporter-like subunits in the membrane domain, NuoL, NuoM, and NuoN (ND5, ND4 and ND2, respectively), are structurally similar. We analyzed the role of NuoN in Escherichia coli NDH-1. The lysine residue at position 395 in NuoN (_NLys³⁹⁵) is conserved in NuoL (_LLys³⁹⁹) but is replaced by glutamic acid (_MGlu⁴⁰⁷) in NuoM. Our mutation study on _NLys³⁹⁵ suggests that this residue participates in the proton translocation. Furthermore, we found that _MGlu⁴⁰⁷ is also essential and most likely interacts with conserved _LArg¹⁷⁵. Glutamic acids, _NGlu¹³³, _MGlu¹⁴⁴, and _LGlu¹⁴⁴, are corresponding residues. Unlike mutants of _MGlu¹⁴⁴ and _LGlu¹⁴⁴, mutation of _NGlu¹³³ scarcely affected the energy-transducing activities. However, a double mutant of _NGlu¹³³ and nearby _KGlu⁷² showed significant inhibition of these activities. This suggests that _NGlu¹³³ bears a functional role similar to _LGlu¹⁴⁴ and _MGlu¹⁴⁴ but its mutation can be partially compensated by the nearby carboxyl residue. Conserved prolines located at loops of discontinuous transmembrane helices of NuoL, NuoM, and NuoN were shown to play a similar role in the energy-transducing activity. It seems likely that NuoL, NuoM, and NuoN pump protons by a similar mechanism. Our data also revealed that _NLys¹⁵⁸ is one of the key interaction points with helix HL in NuoL. A truncation study indicated that the C-terminal amphipathic segments of _NTM14 interacts with the _Mβ sheet located on the opposite side of helix HL. Taken together, the mechanism of H⁺ translocation in NDH-1 is discussed.     

Glycine neurotransmitter transporters: an update

Glycine accomplishes several functions as a transmitter in the central nervous system(CNS). As an inhibitory neurotransmitter, it participates in the processing of motor and sensory information that permits movement, vision, and audition. This action of glycine is mediated by the strychnine-sensitive glycine receptor, whose activation produces inhibitory post-synaptic potentials. In some areas of the CNS, glycine seems to be co-released with GABA, the main inhibitory amino acid neurotransmitter. In addition, glycine modulates excitatory neurotransmission by potentiating the action of glutamate at N-methyl-D-aspartate (NMDA) receptors. It is believed that the termination of the different synaptic actions of glycine is produced by rapid reuptake through two sodium-and-chloride-coupled transporters, GLYT1 and GLYT2, located in the plasma membrane of glial cells or pre-synaptic terminals, respectively. Glycine transporters may become major targets for therapeutic of pathological alterations in synaptic function. This article reviews recent progress on the study of the molecular heterogeneity, localization, function, structure, regulation and pharmacology of the glycine transporter     

Engineered exosomes: A new promise for the management of musculoskeletal diseases

Background

Exosomes are nanovesicles actively secreted by potentially all cell types, including tumour cells, with the primary role of extracellular systemic communication mediators, both at autocrine and paracrine levels, at short and long distances. Recently, different studies have used exosomes as a delivery system for a plethora of different molecules, such as drugs, microRNAs and proteins. This has been made possible thanks to the simplicity in exosomes engineering, their great stability and versatility for applications in oncology as well as in regenerative medicine.

Predicting the cumulative effect of multiple disturbances on seagrass connectivity

The rate of exchange, or connectivity, among populations effects their ability to recover after disturbance events. However, there is limited information on the extent to which populations are connected or how multiple disturbances affect connectivity, especially in coastal and marine ecosystems. We used network analysis and the outputs of a biophysical model to measure potential functional connectivity and predict the impact of multiple disturbances on seagrasses in the central Great Barrier Reef World Heritage Area (GBRWHA), Australia. The seagrass networks were densely connected, indicating that seagrasses are resilient to the random loss of meadows. Our analysis identified discrete meadows that are important sources of seagrass propagules and that serve as stepping stones connecting various different parts of the network. Several of these meadows were close to urban areas or ports and likely to be at risk from coastal development. Deep water meadows were highly connected to coastal meadows and may function as a refuge, but only for non‐foundation species. We evaluated changes to the structure and functioning of the seagrass networks when one or more discrete meadows were removed due to multiple disturbance events. The scale of disturbance required to disconnect the seagrass networks into two or more components was on average >245 km, about half the length of the metapopulation. The densely connected seagrass meadows of the central GBRWHA are not limited by the supply of propagules; therefore, management should focus on improving environmental conditions that support natural seagrass recruitment and recovery processes. Our study provides a new framework for assessing the impact of global change on the connectivity and persistence of coastal and marine ecosystems. Without this knowledge, management actions, including coastal restoration, may prove unnecessary and be unsuccessful.     

S100a4-Cre×Ddr2flox/flox条件敲除小鼠的繁育及基因型鉴定

目的:利用Cre-LoxP重组酶系统构建成纤维细胞中Ddr2特异性敲除的纯合子小鼠并鉴定,为进一步研究Ddr2在肺纤维化中的作用提供基础。方法:将购买的Ddr2 loxp小鼠和成纤维细胞特异表达的S100a4-Cre小鼠分别繁殖与鉴定,然后将两种小鼠杂交与鉴定,最终得到基因型为Cre~× Ddr2~(flox/flox)的纯合子小鼠就是在成纤维细胞中Ddr2条件性敲除小鼠。结果:成功繁殖并用PCR技术准确鉴定了基因型为Cre~× Ddr2~(flox/flox)的纯合子小鼠,Western blot结果表明纯合子小鼠的肺成纤维细胞中Ddr2已缺失。结论:本研究利用Cre-LoxP系统成功构建了在成纤维细胞中Ddr2特异性敲除的纯合子小鼠,为进一步研究Ddr2在肺纤维化发展中的机制提供了研究平台。     

Über die Wirkung von Yohimbin auf das hypothalamisch-neurohypophysäre System der Ratte

Zusammenfassung Die Wirkung von Yohinibin HCl auf das neurosekretorische Hypothalamo-Neurohypophysensystem der Ratte wurde lichtmikroskopisch, insbesondere karyometrisch, untersucht.Unter der Einwirkung von Yohinibin, das subcutan injiziert wird, vermindert sich die Menge des lichtmikroskopisch sichtbaren Neurosekrets im gesamten sekretorischen Neuron. Die Kerndurchmesser der Zellen des Nucleus supraopticus nehmen leicht, aber signifikant zu. Die Abnahme des Neurosekretbestandes wird mit einer verstärkten Ausschüttung aus dem Hinterlappen und einem beschleunigten Transport in den Axonen erklärt. Die Zunahme der Kerndurchmesser kann als Ausdruck einer verstärkten Synthesetätigkeit betrachtet werden. Eine direkte Einwirkung des Yohimbins auf die sekretorischen Neurone ist denkbar, da es sich um einen an adrenerge Strukturen gebundenen Rezeptorenblocker handelt und adrenerge Synapsen im Bereich des neurosekretorischen Hypothalamo-Neurohypophysensystems nachgewiesen worden sind. Aber auch indirekte Wirkungen des Yohimbins auf das neurosekretorische System sind in Betracht zu ziehen, die auf dem Wege über eine Beeinflussung höherer Zentren und aufgrund einer zentralen Anti-Serotonin-Wirkung zustandekommen. Auf die Möglichkeit einer Beeinflussung der Gonadotropinkonzentration durch Yohinibin, die auf dem Wege über eine Veränderung des Funktionszustandes des neurosekretorischen Hypothalamo-Neurohypophysensystems zustande kommt, wird hingewiesen.

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Effects of yohimbine on the hypothalamo-neurohypophysial system of the ratLightmicroscopical investigations

Summary The effect of yohimbine HCl on the neurosecretory hypothalamo-neurohypophysial system of the rat has been investigated lightmicroscopically, and in particular, karyometrically.Under the influence of subcutaneously injected yohimbine the amount of the lightmicroscopically visible neurosecretory material decreases. The diameters of the nuclei of the nerve cells in the supraoptic nucleus increase slightly, but significantly. The diminution of the visible neurosecretory material is interpreted to represent the equivalent of an increased release from the posterior lobe and of an accelerated transport along the axons. The increase of the nuclear diameters is interpreted as an indication of intensified activity. A direct effect on the secretory neurons by yohimbine is imaginable, since yohimbine represents an adrenergic blocking agent, and adrenergic synapses occur in the neurosecretory hypothalamo-neurohypophysial system. But also indirect effects on the neurosecretory system by yohimbine have to be taken into consideration acting on higher centers on the base of a central antiserotonin-effect. Possibly yohimbine exerts its influence on the concentration of gonadotropins by inducing functional changes of the neurosecretory hypothalamo-neurohypophysial system.

     

Large‐scale,multidirectional larval connectivity among coral reef fish populations in the Great Barrier Reef Marine Park

Larval dispersal is the key process by which populations of most marine fishes and invertebrates are connected and replenished. Advances in larval tagging and genetics have enhanced our capacity to track larval dispersal, assess scales of population connectivity, and quantify larval exchange among no‐take marine reserves and fished areas. Recent studies have found that reserves can be a significant source of recruits for populations up to 40 km away, but the scale and direction of larval connectivity across larger seascapes remain unknown. Here, we apply genetic parentage analysis to investigate larval dispersal patterns for two exploited coral reef groupers (Plectropomus maculatus and Plectropomus leopardus) within and among three clusters of reefs separated by 60–220 km within the Great Barrier Reef Marine Park, Australia. A total of 69 juvenile P. maculatus and 17 juvenile P. leopardus (representing 6% and 9% of the total juveniles sampled, respectively) were genetically assigned to parent individuals on reefs within the study area. We identified both short‐distance larval dispersal within regions (200 m to 50 km) and long‐distance, multidirectional dispersal of up to ~250 km among regions. Dispersal strength declined significantly with distance, with best‐fit dispersal kernels estimating median dispersal distances of ~110 km for P. maculatus and ~190 km for P. leopardus. Larval exchange among reefs demonstrates that established reserves form a highly connected network and contribute larvae for the replenishment of fished reefs at multiple spatial scales. Our findings highlight the potential for long‐distance dispersal in an important group of reef fishes, and provide further evidence that effectively protected reserves can yield recruitment and sustainability benefits for exploited fish populations.     

Comparative phylogeography of the western Indian Ocean reef fauna

Assessing patterns of connectivity at the community and population levels is relevant to marine resource management and conservation. The present study reviews this issue with a focus on the western Indian Ocean (WIO) biogeographic province. This part of the Indian Ocean holds more species than expected from current models of global reef fish species richness. In this study, checklists of reef fish species were examined to determine levels of endemism in each of 10 biogeographic provinces of the Indian Ocean. Results showed that the number of endemic species was higher in the WIO than in any other region of the Indian Ocean. Endemic species from the WIO on the average had a larger body size than elsewhere in the tropical Indian Ocean. This suggests an effect of peripheral speciation, as previously documented in the Hawaiian reef fish fauna, relative to other sites in the tropical western Pacific. To explore evolutionary dynamics of species across biogeographic provinces and infer mechanisms of speciation, we present and compare the results of phylogeographic surveys based on compilations of published and unpublished mitochondrial DNA sequences for 19 Indo-Pacific reef-associated fishes (rainbow grouper Cephalopholis argus, scrawled butterflyfish Chaetodon meyeri, bluespot mullet Crenimugil sp. A, humbug damselfish Dascyllus abudafur/Dascyllus aruanus, areolate grouper Epinephelus areolatus, blacktip grouper Epinephelus fasciatus, honeycomb grouper Epinephelus merra, bluespotted cornetfish Fistularia commersonii, cleaner wrasse Labroides sp. 1, longface emperor Lethrinus sp. A, bluestripe snapper Lutjanus kasmira, unicornfishes Naso brevirosris, Naso unicornis and Naso vlamingii, blue-spotted maskray Neotrygon kuhlii, largescale mullet Planiliza macrolepis, common parrotfish Scarus psicattus, crescent grunter Terapon jarbua, whitetip reef shark Triaenodon obesus) and three coastal Indo-West Pacific invertebrates (blue seastar Linckia laevigata, spiny lobster Panulirus homarus, small giant clam Tridacna maxima). Heterogeneous and often unbalanced sampling design, paucity of data in a number of cases, and among-species discrepancy in phylogeographic structure precluded any generalization regarding phylogeographic patterns. Nevertheless, the WIO might have been a source of haplotypes in some cases and it also harboured an endemic clade in at least one case. The present survey also highlighted likely cryptic species. This may eventually affect the accuracy of the current checklists of species, which form the basis of some of the recent advances in Indo-West Pacific marine ecology and biogeography.