Ecological and genetic data indicate recovery of the endangered coral Acropora palmata in Los Roques, Southern Caribbean

The rapid decline of Acropora cervicornis and Acropora palmata has often been linked with coral reef deterioration in the Caribbean; yet, it remains controversial whether these species are currently recovering or still declining. In this study, the status of ten populations of A. palmata in Los Roques National Park (LRNP), Venezuela is presented. Six of these populations showed signs of recovery. Ten 80 m² belt-transects were surveyed at each of the ten reef sites. Within belt-transects, each colony was measured (maximum diameter and height) and its status (healthy, diseased or injured) was recorded. Populations in recovery were defined by a dominance of small to medium-sized colonies in densities >1 colony per 10 m², together with 75% undamaged colonies, a low prevalence of diseases (<10%), and a low density of predators (0.25 snails per colony). Based on allozyme analysis of seven polymorphic loci in four populations (N = 30), a moderate to high-genetic connectivity among these populations (F _ST = 0.048) was found with a predominance of sexual over asexual reproduction (N* : N = 1; N _go : N = 0.93–1). Both ecological and molecular data support a good prognosis for the recovery of this species in Los Roques.     

Nicotine and its metabolites. Radioimmunoassay for gamma-(3-pyridyl)-gamma-oxo-N-methylbutyramide

A radioimmunoassay has been developed for the nicotine metabolite γ-(3-pyridyl)-γ-oxo-N-methylbutyramide. The sensitivity and specificity of the assay allow the determination of this compound at the picomole level in the presence of several structurally related molecules including nicotine and seven other nicotine metabolites. The assay has been used to characterize the enzyme system present in rabbit liver extract responsible for the conversion of cotinine to the oxoamide, and to measure oxoamide levels in urine, sera, and amniotic fluid of smokers. High-pressure liquid chromatography was used as an independent method to follow the enzymatic oxidation and in conjunction with the radioimmunoassay to analyze the urine samples.     

Esophageal squamous cell carcinoma and adenocarcinoma in Malaysia – Pooled data from upper gastrointestinal centers in a multiethnic Asian population

BackgroundEsophageal cancer is the sixth leading cause of cancer death worldwide with considerable geographical histological variation There is a paucity of data in esophageal cancer in demographics, histology, and survival among the multi-ethnic Malaysian population. This paper is a review of esophageal cancer epidemiology and survival among esophageal cancer patients from data collected by the Malaysian Upper Gastrointestinal Surgical Society.MethodsThis is a multicenter retrospective observational study of esophageal cancer patients from six upper gastrointestinal surgical centers in Malaysia between 2005 and 2019. Patient characteristics, histological type and stage were compared and survival analyzed.ResultsThere were 820 patients with esophageal cancer included, where 442 (53.9 %) cases had squamous cell carcinoma (SCC) and 378 (46.1 %) had adenocarcinomas (AC). Malays were the predominant ethnicity with AC (66.7 %) while Indians were the ethnic majority (74.6 %) with SCC. Majority of patients (56.8 %) presented as stage IV disease. Overall, the 1-, 3-, and 5-years’ survival were 35.8 %, 13.8 % and 11.0 %, respectively. Surgical resection with curative intent yielded the best 5-year survival (29.4 %). Intervention in stage IV AC yielded superior survival when compared to SCC (median survival, 7.9 months vs 4.8 months; p, 0.018) Our series demonstrated an increase in AC to SCC over the last 15 years.ConclusionsThere was an ethnic preponderance seen between different histology in this region, not previously discussed. An increase in AC was observed over the last 15 years. Late diagnosis seen in most patients imparts poor prognosis as curative surgery affords the best outcome.     

Flavone-resistant Leishmania donovani Overexpresses LdMRP2 Transporter in the Parasite and Activates Host MRP2 on Macrophages to Circumvent the Flavone-mediated Cell Death

In parasites, ATP-binding cassette (ABC) transporters represent an important family of proteins related to drug resistance and other biological activities. Resistance of leishmanial parasites to therapeutic drugs continues to escalate in developing countries, and in many instances, it is due to overexpressed ABC efflux pumps. Progressively adapted baicalein (BLN)-resistant parasites (pB²⁵R) show overexpression of a novel ABC transporter, which was classified as ABCC2 or Leishmania donovani multidrug resistance protein 2 (LdMRP2). The protein is primarily localized in the flagellar pocket region and in internal vesicles. Overexpressed LdABCC2 confers substantial BLN resistance to the parasites by rapid drug efflux. The BLN-resistant promastigotes when transformed into amastigotes in macrophage cells cannot be cured by treatment of macrophages with BLN. Amastigote resistance is concomitant with the overexpression of macrophage MRP2 transporter. Reporter analysis and site-directed mutagenesis assays demonstrated that antioxidant response element 1 is activated upon infection. The expression of this phase II detoxifying gene is regulated by NFE2-related factor 2 (Nrf2)-mediated antioxidant response element activation. In view of the fact that the signaling pathway of phosphoinositol 3-kinase controls microfilament rearrangement and translocation of actin-associated proteins, the current study correlates with the intricate pathway of phosphoinositol 3-kinase-mediated nuclear translocation of Nrf2, which activates MRP2 expression in macrophages upon infection by the parasites. In contrast, phalloidin, an agent that prevents depolymerization of actin filaments, inhibits Nrf2 translocation and Mrp2 gene activation by pB²⁵R infection. Taken together, these results provide insight into the mechanisms by which resistant clinical isolates of L. donovani induce intracellular events relevant to drug resistance.     

ATP and AMP Mutually Influence Their Interaction with the ATP-binding Cassette (ABC) Adenylate Kinase Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) at Separate Binding Sites

Cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel in the ATP-binding cassette (ABC) transporter protein family. In the presence of ATP and physiologically relevant concentrations of AMP, CFTR exhibits adenylate kinase activity (ATP + AMP ⇆ 2 ADP). Previous studies suggested that the interaction of nucleotide triphosphate with CFTR at ATP-binding site 2 is required for this activity. Two other ABC proteins, Rad50 and a structural maintenance of chromosome protein, also have adenylate kinase activity. All three ABC adenylate kinases bind and hydrolyze ATP in the absence of other nucleotides. However, little is known about how an ABC adenylate kinase interacts with ATP and AMP when both are present. Based on data from non-ABC adenylate kinases, we hypothesized that ATP and AMP mutually influence their interaction with CFTR at separate binding sites. We further hypothesized that only one of the two CFTR ATP-binding sites is involved in the adenylate kinase reaction. We found that 8-azidoadenosine 5′-triphosphate (8-N₃-ATP) and 8-azidoadenosine 5′-monophosphate (8-N₃-AMP) photolabeled separate sites in CFTR. Labeling of the AMP-binding site with 8-N₃-AMP required the presence of ATP. Conversely, AMP enhanced photolabeling with 8-N₃-ATP at ATP-binding site 2. The adenylate kinase active center probe P¹,P⁵-di(adenosine-5′) pentaphosphate interacted simultaneously with an AMP-binding site and ATP-binding site 2. These results show that ATP and AMP interact with separate binding sites but mutually influence their interaction with the ABC adenylate kinase CFTR. They further indicate that the active center of the adenylate kinase comprises ATP-binding site 2.     

Enhanced biosynthesis of coagulation factor VIII through diminished engagement of the unfolded protein response

Human and porcine coagulation factor VIII (fVIII) display a biosynthetic efficiency differential that is being exploited for the development of new protein and gene transfer-based therapies for hemophilia A. The cellular and/or molecular mechanism(s) responsible for this phenomenon have yet to be uncovered, although it has been temporally localized to post-translational biosynthetic steps. The unfolded protein response (UPR) is a cellular adaptation to structurally distinct (e.g. misfolded) or excess protein in the endoplasmic reticulum and is known to be induced by heterologous expression of recombinant human fVIII. Therefore, it is plausible that the biosynthetic differential between human and porcine fVIII results from differential UPR activation. In the current study, UPR induction was examined in the context of ongoing fVIII expression. UPR activation was greater during human fVIII expression when compared with porcine fVIII expression as determined by ER response element (ERSE)-luciferase reporter activity, X-box-binding protein 1 (XBP1) splicing, and immunoglobulin-binding protein (BiP) up-regulation. Immunofluorescence microscopy of fVIII expressing cells revealed that human fVIII was notably absent in the Golgi apparatus, confirming that endoplasmic reticulum to Golgi transport is rate-limiting. In contrast, a significant proportion of porcine fVIII was localized to the Golgi indicating efficient transit through the secretory pathway. Overexpression of BiP, an integral UPR protein, reduced the secretion of human fVIII by 50%, but had no effect on porcine fVIII biosynthesis. In contrast, expression of BiP shRNA increased human fVIII expression levels. The current data support the model of differential engagement of UPR by human and porcine fVIII as a non-traditional mechanism for regulation of gene product biosynthesis.     

Mitochondrial Protein Acylation and Intermediary Metabolism: Regulation by Sirtuins and Implications for Metabolic Disease

The sirtuins are a family of NAD⁺-dependent protein deacetylases that regulate cell survival, metabolism, and longevity. Three sirtuins, SIRT3–5, localize to mitochondria. Expression of SIRT3 is selectively activated during fasting and calorie restriction. SIRT3 regulates the acetylation level and enzymatic activity of key metabolic enzymes, such as acetyl-CoA synthetase, long-chain acyl-CoA dehydrogenase, and 3-hydroxy-3-methylglutaryl-CoA synthase 2, and enhances fat metabolism during fasting. SIRT5 exhibits demalonylase/desuccinylase activity, and lysine succinylation and malonylation are abundant mitochondrial protein modifications. No convincing enzymatic activity has been reported for SIRT4. Here, we review the emerging role of mitochondrial sirtuins as metabolic sensors that respond to changes in the energy status of the cell and modulate the activities of key metabolic enzymes via protein deacylation.     

Human and Pneumococcal Cell Surface Glyceraldehyde-3-phosphate Dehydrogenase (GAPDH) Proteins Are Both Ligands of Human C1q Protein

C1q, a key component of the classical complement pathway, is a major player in the response to microbial infection and has been shown to detect noxious altered-self substances such as apoptotic cells. In this work, using complementary experimental approaches, we identified the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a C1q partner when exposed at the surface of human pathogenic bacteria Streptococcus pneumoniae and human apoptotic cells. The membrane-associated GAPDH on HeLa cells bound the globular regions of C1q as demonstrated by pulldown and cell surface co-localization experiments. Pneumococcal strains deficient in surface-exposed GAPDH harbored a decreased level of C1q recognition when compared with the wild-type strains. Both recombinant human and pneumococcal GAPDHs interacted avidly with C1q as measured by surface plasmon resonance experiments (K_D = 0.34–2.17 nm). In addition, GAPDH-C1q complexes were observed by transmission electron microscopy after cross-linking. The purified pneumococcal GAPDH protein activated C1 in an in vitro assay unlike the human form. Deposition of C1q, C3b, and C4b from human serum at the surface of pneumococcal cells was dependent on the presence of surface-exposed GAPDH. This ability of C1q to sense both human and bacterial GAPDHs sheds new insights on the role of this important defense collagen molecule in modulating the immune response.     

Synthetic Dimeric Aβ(28–40) Mimics the Complex Epitope of Human Anti-Aβ Autoantibodies against Toxic Aβ Oligomers

Covalently linked carboxyl-terminal segments of the β-amyloid peptide (Aβ) were tested for their qualification as minimal conformational epitopes of the naturally occurring human autoantibodies against β-amyloid (nAbs-Aβ). nAbs-Aβ specifically recognize the toxic oligomers of Aβ and not the monomeric or the fibrillar forms of Aβ. The synthetic dimers of Aβ(28–40) described herein mimic the toxic Aβ oligomers but are not kinetic intermediates with uncertain compositions. CD spectra identified a surprisingly rich conformational behavior of selected miniamyloids. We observed a highly cooperative conformational transition of β-sheet to α-helix upon the addition of the helix enforcing co-solvent hexafluoroisopropanol. The CD curves of dimer 9 resembled, in a completely reversible manner, the CD spectra measured during the irreversible fibrillation of the parent Aβ(1–40). Synthetic peptide epitopes with high affinities for nAbs-Aβ are needed to identify the physiological roles of nAbs-Aβ and are promising epitopes for vaccination experiments.     

Effects of Hydrogen Sulfide-releasing l-DOPA Derivatives on Glial Activation: POTENTIAL FOR TREATING PARKINSON DISEASE*

The main lesion in Parkinson disease (PD) is loss of substantia nigra dopaminergic neurons. Levodopa (l-DOPA) is the most widely used therapy, but it does not arrest disease progression. Some possible contributing factors to the continuing neuronal loss are oxidative stress, including oxidation of l-DOPA, and neurotoxins generated by locally activated microglia and astrocytes. A possible method of reducing these factors is to produce l-DOPA hybrid compounds that have antioxidant and antiinflammatory properties. Here we demonstrate the properties of four such l-DOPA hybrids based on coupling l-DOPA to four different hydrogen sulfide-donating compounds. The donors themselves were shown to be capable of conversion by isolated mitochondria to H₂S or equivalent SH⁻ ions. This capability was confirmed by in vivo results, showing a large increase in intracerebral dopamine and glutathione after iv administration in rats. When human microglia, astrocytes, and SH-SY5Y neuroblastoma cells were treated with these donating agents, they all accumulated H₂S intracellularly as did their derivatives coupled to l-DOPA. The donating agents and the l-DOPA hybrids reduced the release of tumor necrosis factor-α, interleukin-6, and nitric oxide from stimulated microglia, astrocytes as well as the THP-1 and U373 cell lines. They also demonstrated a neuroprotective effect by reducing the toxicity of supernatants from these stimulated cells to SH-SY5Y cells. l-DOPA itself was without effect in any of these assays. The H₂S-releasing l-DOPA hybrid molecules also inhibited MAO B activity. They may be useful for the treatment of PD because of their significant antiinflammatory, antioxidant, and neuroprotective properties.