Distribution and Numbers of Pygmies in Central African Forests

Pygmy populations occupy a vast territory extending west-to-east along the central African belt from the Congo Basin to Lake Victoria. However, their numbers and actual distribution is not known precisely. Here, we undertake this task by using locational data and population sizes for an unprecedented number of known Pygmy camps and settlements (n = 654) in five of the nine countries where currently distributed. With these data we develop spatial distribution models based on the favourability function, which distinguish areas with favourable environmental conditions from those less suitable for Pygmy presence. Highly favourable areas were significantly explained by presence of tropical forests, and by lower human pressure variables. For documented Pygmy settlements, we use the relationship between observed population sizes and predicted favourability values to estimate the total Pygmy population throughout Central Africa. We estimate that around 920,000 Pygmies (over 60% in DRC) is possible within favourable forest areas in Central Africa. We argue that fragmentation of the existing Pygmy populations, alongside pressure from extractive industries and sometimes conflict with conservation areas, endanger their future. There is an urgent need to inform policies that can mitigate against future external threats to these indigenous peoples’ culture and lifestyles.     

Inter-proteomic posttranslational modifications of the SARS-CoV-2 and the host proteins ‒ A new frontier

Posttranslational modification of proteins, which include both the enzymatic alterations of protein side chains and main-chain peptide bond connectivity, is a fundamental regulatory process that is crucial for almost every aspects of cell biology, including the virus-host cell interaction and the SARS-CoV-2 infection. The posttranslational modification of proteins has primarily been studied in cells and tissues in an intra-proteomic context (where both substrates and enzymes are part of the same species). However, the inter-proteomic posttranslational modifications of most of the SARS-CoV-2 proteins by the host enzymes and vice versa are largely unexplored in virus pathogenesis and in the host immune response. It is now known that the structural spike (S) protein of the SARS-CoV-2 undergoes proteolytic priming by the host serine proteases for entry into the host cells, and N- and O-glycosylation by the host cell enzymes during virion packaging, which enable the virus to spread. New evidence suggests that both SARS-CoV-2 and the host proteins undergo inter-proteomic posttranslational modifications, which play roles in virus pathogenesis and infection-induced immune response by hijacking the host cell signaling. The purpose of this minireview is to bring attention of the scientific community to recent cutting-edge discoveries in this understudied area. It is likely that a better insight into the molecular mechanisms involved may open new research directions, and thereby contribute to novel therapeutic modality development against the SARS-CoV-2. Here we briefly discuss the rationale and touch upon some unanswered questions in this context, especially those that require attention from the scientific community.     

The novel anticytomegalovirus compound AIC246 (Letermovir) inhibits human cytomegalovirus replication through a specific antiviral mechanism that involves the viral terminase

Human cytomegalovirus (HCMV) remains the leading viral cause of birth defects and life-threatening disease in transplant recipients. All approved antiviral drugs target the viral DNA polymerase and are associated with severe toxicity issues and the emergence of drug resistance. Attempts to discover improved anti-HCMV drugs led to the identification of the small-molecular-weight compound AIC246 (Letermovir). AIC246 exhibits outstanding anti-HCMV activity in vitro and in vivo and currently is undergoing a clinical phase IIb trial. The initial mode-of-action studies suggested that the drug acts late in the HCMV replication cycle via a mechanism distinct from that of polymerase inhibitors. Here, we extend our mode-of-action analyses and report that AIC246 blocks viral replication without inhibiting the synthesis of progeny HCMV DNA or viral proteins. The genotyping of mutant viruses that escaped AIC246 inhibition uncovered distinct point mutations in the UL56 subunit of the viral terminase complex. Marker transfer analyses confirmed that these mutations were sufficient to mediate AIC246 resistance. The mapping of drug resistance to open reading frame UL56 suggests that viral DNA processing and/or packaging is targeted by AIC246. In line with this, we demonstrate that AIC246 affects the formation of proper unit-length genomes from viral DNA concatemers and interferes with virion maturation. However, since AIC246-resistant viruses do not exhibit cross-resistance to previously published terminase inhibitors, our data suggest that AIC246 interferes with HCMV DNA cleavage/packaging via a molecular mechanism that is distinct from that of other compound classes known to target the viral terminase.     

Role of Ni in coupling angiotensin receptors to inhibition of adenylate cyclase in hepatocytes

Angiotensin II can inhibit glucagon-stimulated cyclic AMP production in hepatocytes and adenylate cyclase activity in hepatic membranes. Pertussis toxin, an exotoxin produced by Bordetella pertussis, was used to investigate the role of the inhibitory guanine nucleotide-binding regulatory protein of adenylate cyclase (Ni) in coupling angiotensin receptors to the adenylate cyclase system. An assay was developed using [32P] NAD+ to quantitate the amount of Ni protein in the membrane and the extent of its ADP-ribosylation catalyzed by toxin. The ability of angiotensin to inhibit adenylate cyclase and interact with its receptor was compared with the degree of modification of Ni in membranes prepared from isolated hepatocytes. In control membranes angiotensin II inhibited basal adenylate cyclase by 35%. When all of the Ni molecules in the membrane were ADP-ribosylated, angiotensin did not inhibit adenylate cyclase. However, the attenuation of angiotensin's effect on cyclase was not linearly correlated with the degree of modification of Ni; ADP-ribosylation of greater than 80% of the Ni was required before a reduction of the angiotensin effect was observed. A possible explanation for this finding is an excess of Ni molecules in the membrane (approximately 3.4 pmol/mg of membrane protein) over angiotensin II receptors (approximately 1.2 pmol/mg of membrane protein). 125I-angiotensin bound to sites in the membrane with two affinities. Computer fitting of the binding isotherms yielded parameters of N1 = 279 fmol/mg protein, Kd1 = 0.2 nM; N2 = 904 fmol/mg protein, Kd2 = 1.4 nM. When all of the Ni molecules in the membrane were ADP-ribosylated, angiotensin bound to only one site with binding parameters of N = 349 fmol/mg protein, Kd = 0.4 nM. GTP-gamma-S caused a 7-fold increase in the Kd of this site to 2.7 nM. Overall, the data indicate that the Ni protein mediates the effect of angiotensin on adenylate cyclase. The observation that GTP-gamma-S can markedly decrease the affinity of angiotensin receptors when all Ni molecules are ADP-ribosylated suggests that angiotensin receptors may couple to other GTP-binding proteins which may mediate the effects of angiotensin in other signal transduction systems.     

ADP-ribosylation of transducin by pertussis toxin

Transducin, the guanyl nucleotide-binding regulatory protein of retinal rod outer segments that couples the photon receptor, rhodopsin, with the light-activated cGMP phosphodiesterase, can be resolved into two functional components, T alpha and T beta gamma. T alpha (39 kDa), which is [32P]ADP-ribosylated by pertussis toxin and [32P]NAD in rod outer segments and in purified transducin, was also labeled by the toxin after separation from T beta gamma (36 kDa and approximately 10 kDa); neither component of T beta gamma was a pertussis toxin substrate. Labeling of T alpha was enhanced by T beta gamma and was maximal at approximately 1:1 molar ratio of T alpha : T beta gamma. Limited proteolysis by trypsin of T alpha in the presence of guanyl-5'-yl imidodiphosphate (Gpp(NH)p) resulted in the sequential appearance of proteins of 38 and 32 kDa. The amino terminus of both 38- and 32-kDa proteins was leucine, whereas that of T alpha could not be identified and was assumed to be blocked. The 32-kDa peptide was not a pertussis toxin substrate. Labeling of the 38-kDa protein was poor and was not enhanced by T beta gamma. Trypsin treatment of [32P]ADP-ribosyl-T alpha produced a labeled 37-38-kDa doublet followed by appearance of radioactivity at the dye front. It appears, therefore, that, although the 38-kDa protein was poor toxin substrate, it contained the ADP-ribosylation site. Without rhodopsin, labeling of T alpha (in the presence of T beta gamma) was unaffected by Gpp(NH)p, guanosine 5'-O-(thiotriphosphate) (GTP gamma S), GTP, GDP, and guanosine 5'-O-(thiodiphosphate) (GDP beta S) but was increased by ATP. When photolyzed rhodopsin and T beta gamma were present, Gpp(NH)p and GTP gamma S decreased [32P]ADP-ribosylation by pertussis toxin. Thus, pertussis toxin-catalyzed [32P]ADP-ribosylation of T alpha was affected by nucleotides, rhodopsin and light in addition to T beta gamma. The amino terminus of T alpha, while it does not contain the pertussis toxin ADP-ribosylation site, appeared critical to its reactivity.     

Social Networks and Knowledge Transmission Strategies among Baka Children,Southeastern Cameroon

The dynamics of knowledge transmission and acquisition, or how different aspects of culture are passed from one individual to another and how they are acquired and embodied by individuals, are central to understanding cultural evolution. In small-scale societies, cultural knowledge is largely acquired early in life through observation, imitation, and other forms of social learning embedded in daily experiences. However, little is known about the pathways through which such knowledge is transmitted, especially during middle childhood and adolescence. This study presents new empirical data on cultural knowledge transmission during childhood. Data were collected among the Baka, a forager-farmer society in southeastern Cameroon. We conducted structured interviews with children between 5 and 16 years of age (n?=?58 children; 177 interviews, with children being interviewed 1–6 times) about group composition during subsistence activities. Children’s groups were generally diverse, although children tended to perform subsistence activities primarily without adults and with same-sex companions. Group composition varied from one subsistence activity to another, which suggests that the flow of knowledge might also vary according to the activity performed. Analysis of the social composition of children’s subsistence groups shows that vertical and oblique transmission of subsistence-related knowledge might not be predominant during middle childhood and adolescence. Rather, horizontal transmission appears to be the most common knowledge transmission strategy used by Baka children during middle childhood and adolescence, highlighting the importance of other children in the transmission of knowledge.     

Bacterial adenylate cyclase increases cyclic AMP and hormone release in pituitary tumor cells

Calmodulin-activated, adenylate cyclase toxin, a virulence factor produced by the human respiratory pathogen Bordetella pertussis, elicits marked accumulation of cyclic AMP in cell lines from rat pituitary tumors. This effect is associated with and apparently responsible for an enhanced release of prolactin and/or growth hormone from GH3, GH4C1 and 235-1 cells. The utility of this novel toxin in probing cyclic AMP-mediated responses is supported by these observations and studies with pertussis and cholera toxins.     

T-Even Bacteriophage-Tolerant Mutants of Escherichia coli B II. Nucleic Acid Metabolism

T-even bacteriophage-tolerant mutants are strains of Escherichia coli which can adsorb T-even phages but cannot support the growth of infective virus. Under some conditions, the infected cells are not killed. Mutant cells infected by phage T6 are able to carry out several metabolic functions associated with normal virus development, including arrest of bacterial nucleic acid and protein synthesis, incorporation of isotopic precursors into viral nucleic acids and proteins, synthesis of early enzymes of deoxyribonucleic acid (DNA) metabolism, formation of rapidly sedimenting DNA intermediates, and formation of normal levels of early and late messenger ribonucleic acid species. Phage are unable to mutate to forms capable of growth on these mutants. The nature of the biochemical alteration leading to tolerance is still unknown.     

Cannabinoid Receptor-Regulated Cyclic AMP Accumulation in the Rat Striatum

The present study demonstrates that desacetyllevonantradol, a synthetic cannabinoid analog, reduces cyclic AMP levels in rat striatal slices stimulated with vasoactive intestinal peptide or SKF 38393, a D1-dopamine agonist. Desacetyllevonantradol and the D2 agonist LY 171555 both inhibited D1-stimulated cyclic AMP accumulation in the striatum. Spiperone, a specific D2-dopamine antagonist, fully reversed the inhibitory effect of LY 171555 but not that of desacetyllevonantradol, indicating that this cannabinoid response is not occurring through a D2-dopaminergic mechanism. Morphine also inhibited cyclic AMP accumulation in striatal slices stimulated with either SKF 38393 or vasoactive intestinal peptide. Naloxone, an opioid antagonist, fully reversed the effect of morphine but not that of desacetyllevonantradol, indicating that cannabinoid drugs are not acting via a mechanism involving opioid receptors. The response to maximally effective concentrations of desacetyllevonantradol was not additive to that of maximally effective concentrations of either morphine or LY 171555, suggesting that dopaminergic, opioid, and cannabinoid receptors may be present on the same populations of cells.