Family, friends, and community members gathered on Saturday at the Falmouth First Assembly Church to celebrate the life of 15-year-old Jahmarie Reid, a William Knibb High student who tragically lost his life at sea on August 27 in what is believed...

Kadian Morgan was overwhelmed with grief as she leaned against a wall outside her gate on Jackson Lane, East Kingston, yesterday, tears streaming down her face. Her 19-year-old son, Kayshan 'Bem Bem' Smith, was lying in the morgue after being...

A police sergeant who was shot and injured at his home in Portmore, St Catherine, on Thursday night succumbed to his injuries on Monday morning.

A father who pleaded guilty to sexually molesting his 13-year-old daughter was sentenced to several years of imprisonment in the St Catherine Circuit Court on Tuesday.

Infiltration of peripheral immune cells after blood-brain barrier dysfunction causes severe inflammation after a stroke. Although the endothelial glycocalyx, a network of membrane-bound glycoproteins and proteoglycans that covers the lumen of endothelial cells, functions as a barrier to circulating cells, the relationship between stroke severity and glycocalyx dysfunction remains unclear. In this study, glycosaminoglycans, a component of the endothelial glycocalyx, were studied in the context of ischemic stroke using a photochemically induced thrombosis mouse model. Decreased levels of heparan sulfate and chondroitin sulfate and increased activity of hyaluronidase 1 and heparanase (HPSE) were observed in ischemic brain tissues. HPSE expression in cerebral vessels increased after stroke onset and infarct volume greatly decreased after co-administration of N-acetylcysteine + glycosaminoglycan oligosaccharides as compared with N-acetylcysteine administration alone. These results suggest that the endothelial glycocalyx was injured after the onset of stroke. Interestingly, scission activity of proHPSE produced by immortalized endothelial cells and HEK293 cells transfected with hHPSE1 cDNA were activated by acrolein (ACR) exposure. We identified the ACR-modified amino acid residues of proHPSE using nano LC–MS/MS, suggesting that ACR modification of Lys139 (6-kDa linker), Lys107, and Lys161, located in the immediate vicinity of the 6-kDa linker, at least in part is attributed to the activation of proHPSE. Because proHPSE, but not HPSE, localizes outside cells by binding with heparan sulfate proteoglycans, ACR-modified proHPSE represents a promising target to protect the endothelial glycocalyx.

α-Linked galactose is a common carbohydrate motif in nature that is processed by a variety of glycoside hydrolases from different families. Terminal Galα1–3Gal motifs are found as a defining feature of different blood group and tissue antigens, as well as the building block of the marine algal galactan λ-carrageenan. The blood group B antigen and linear α-Gal epitope can be processed by glycoside hydrolases in family GH110, whereas the presence of genes encoding GH110 enzymes in polysaccharide utilization loci from marine bacteria suggests a role in processing λ-carrageenan. However, the structure–function relationships underpinning the α-1,3-galactosidase activity within family GH110 remain unknown. Here we focus on a GH110 enzyme (PdGH110B) from the carrageenolytic marine bacterium Pseudoalteromonas distincta U2A. We showed that the enzyme was active on Galα1–3Gal but not the blood group B antigen. X-ray crystal structures in complex with galactose and unhydrolyzed Galα1–3Gal revealed the parallel β-helix fold of the enzyme and the structural basis of its inverting catalytic mechanism. Moreover, an examination of the active site reveals likely adaptations that allow accommodation of fucose in blood group B active GH110 enzymes or, in the case of PdGH110, accommodation of the sulfate groups found on λ-carrageenan. Overall, this work provides insight into the first member of a predominantly marine clade of GH110 enzymes while also illuminating the structural basis of α-1,3-galactoside processing by the family as a whole.

Proteins in the α-macroglobulin (αM) superfamily use thiol esters to form covalent conjugation products upon their proteolytic activation. αM protease inhibitors use theirs to conjugate proteases and preferentially react with primary amines (e.g. on lysine side chains), whereas those of αM complement components C3 and C4B have an increased hydroxyl reactivity that is conveyed by a conserved histidine residue and allows conjugation to cell surface glycans. Human α2-macroglobulin–like protein 1 (A2ML1) is a monomeric protease inhibitor but has the hydroxyl reactivity–conveying histidine residue. Here, we have investigated the role of hydroxyl reactivity in a protease inhibitor by comparing recombinant WT A2ML1 and the A2ML1 H1084N mutant in which this histidine is removed. Both of A2ML1s' thiol esters were reactive toward the amine substrate glycine, but only WT A2ML1 reacted with the hydroxyl substrate glycerol, demonstrating that His-1084 increases the hydroxyl reactivity of A2ML1's thiol ester. Although both A2ML1s conjugated and inhibited thermolysin, His-1084 was required for the conjugation and inhibition of acetylated thermolysin, which lacks primary amines. Using MS, we identified an ester bond formed between a thermolysin serine residue and the A2ML1 thiol ester. These results demonstrate that a histidine-enhanced hydroxyl reactivity can contribute to protease inhibition by an αM protein. His-1084 did not improve A2ML1's protease inhibition at pH 5, indicating that A2ML1's hydroxyl reactivity is not an adaption to its acidic epidermal environment.

Broad-specificity glycoside hydrolases (GHs) contribute to plant biomass hydrolysis by degrading a diverse range of polysaccharides, making them useful catalysts for renewable energy and biocommodity production. Discovery of new GHs with improved kinetic parameters or more tolerant substrate-binding sites could increase the efficiency of renewable bioenergy production even further. GH5 has over 50 subfamilies exhibiting selectivities for reaction with β-(1,4)–linked oligo- and polysaccharides. Among these, subfamily 4 (GH5_4) contains numerous broad-selectivity endoglucanases that hydrolyze cellulose, xyloglucan, and mixed-linkage glucans. We previously surveyed the whole subfamily and found over 100 new broad-specificity endoglucanases, although the structural origins of broad specificity remained unclear. A mechanistic understanding of GH5_4 substrate specificity would help inform the best protein design strategies and the most appropriate industrial application of broad-specificity endoglucanases. Here we report structures of 10 new GH5_4 enzymes from cellulolytic microbes and characterize their substrate selectivity using normalized reducing sugar assays and MS. We found that GH5_4 enzymes have the highest catalytic efficiency for hydrolysis of xyloglucan, glucomannan, and soluble β-glucans, with opportunistic secondary reactions on cellulose, mannan, and xylan. The positions of key aromatic residues determine the overall reaction rate and breadth of substrate tolerance, and they contribute to differences in oligosaccharide cleavage patterns. Our new composite model identifies several critical structural features that confer broad specificity and may be readily engineered into existing industrial enzymes. We demonstrate that GH5_4 endoglucanases can have broad specificity without sacrificing high activity, making them a valuable addition to the biomass deconstruction toolset.

Arabinogalactan proteins (AGPs) are plant proteoglycans with functions in growth and development. However, these functions are largely unexplored, mainly because of the complexity of the sugar moieties. These carbohydrate sequences are generally analyzed with the aid of glycoside hydrolases. The exo-β-1,3-galactanase is a glycoside hydrolase from the basidiomycete Phanerochaete chrysosporium (Pc1,3Gal43A), which specifically cleaves AGPs. However, its structure is not known in relation to its mechanism bypassing side chains. In this study, we solved the apo and liganded structures of Pc1,3Gal43A, which reveal a glycoside hydrolase family 43 subfamily 24 (GH43_sub24) catalytic domain together with a carbohydrate-binding module family 35 (CBM35) binding domain. GH43_sub24 is known to lack the catalytic base Asp conserved among other GH43 subfamilies. Our structure in combination with kinetic analyses reveals that the tautomerized imidic acid group of Gln263 serves as the catalytic base residue instead. Pc1,3Gal43A has three subsites that continue from the bottom of the catalytic pocket to the solvent. Subsite −1 contains a space that can accommodate the C-6 methylol of Gal, enabling the enzyme to bypass the β-1,6–linked galactan side chains of AGPs. Furthermore, the galactan-binding domain in CBM35 has a different ligand interaction mechanism from other sugar-binding CBM35s, including those that bind galactomannan. Specifically, we noted a Gly → Trp substitution, which affects pyranose stacking, and an Asp → Asn substitution in the binding pocket, which recognizes β-linked rather than α-linked Gal residues. These findings should facilitate further structural analysis of AGPs and may also be helpful in engineering designer enzymes for efficient biomass utilization.

Systemic antibody light chains (AL) amyloidosis is characterized by deposition of amyloid fibrils derived from a particular antibody light chain. Cardiac involvement is a major risk factor for mortality. Using MAS solid-state NMR, we studied the fibril structure of a recombinant light chain fragment corresponding to the fibril protein from patient FOR005, together with fibrils formed by protein sequence variants that are derived from the closest germline (GL) sequence. Both analyzed fibril structures were seeded with ex-vivo amyloid fibrils purified from the explanted heart of this patient. We find that residues 11-42 and 69-102 adopt β-sheet conformation in patient protein fibrils. We identify arginine-49 as a key residue that forms a salt bridge to aspartate-25 in the patient protein fibril structure. In the germline sequence, this residue is replaced by a glycine. Fibrils from the GL protein and from the patient protein harboring the single point mutation R49G can be both heterologously seeded using patient ex-vivo fibrils. Seeded R49G fibrils show an increased heterogeneity in the C-terminal residues 80-102, which is reflected by the disappearance of all resonances of these residues. By contrast, residues 11-42 and 69-77, which are visible in the MAS solid-state NMR spectra, show 13Cα chemical shifts that are highly like patient fibrils. The mutation R49G thus induces a conformational heterogeneity at the C terminus in the fibril state, whereas the overall fibril topology is retained. These findings imply that patient mutations in FOR005 can stabilize the fibril structure.

The dimeric ectonucleotidase CD73 catalyzes the hydrolysis of AMP at the cell surface to form adenosine, a potent suppressor of the immune response. Blocking CD73 activity in the tumor microenvironment can have a beneficial effect on tumor eradication and is a promising approach for cancer therapy. Biparatopic antibodies binding different regions of CD73 may be a means to antagonize its enzymatic activity. A panel of biparatopic antibodies representing the pairwise combination of 11 parental monoclonal antibodies against CD73 was generated by Fab-arm exchange. Nine variants vastly exceeded the potency of their parental antibodies with ≥90% inhibition of activity and subnanomolar EC50 values. Pairing the Fabs of parents with nonoverlapping epitopes was both sufficient and necessary whereas monovalent antibodies were poor inhibitors. Some parental antibodies yielded potent biparatopics with multiple partners, one of which (TB19) producing the most potent. The structure of the TB19 Fab with CD73 reveals that it blocks alignment of the N- and C-terminal CD73 domains necessary for catalysis. A separate structure of CD73 with a Fab (TB38) which complements TB19 in a particularly potent biparatopic shows its binding to a nonoverlapping site on the CD73 N-terminal domain. Structural modeling demonstrates a TB19/TB38 biparatopic antibody would be unable to bind the CD73 dimer in a bivalent manner, implicating crosslinking of separate CD73 dimers in its mechanism of action. This ability of a biparatopic antibody to both crosslink CD73 dimers and fix them in an inactive conformation thus represents a highly effective mechanism for the inhibition of CD73 activity.

Abnormal changes of neuronal Tau protein, such as phosphorylation and aggregation, are considered hallmarks of cognitive deficits in Alzheimer's disease. Abnormal phosphorylation is thought to precede aggregation and therefore to promote aggregation, but the nature and extent of phosphorylation remain ill-defined. Tau contains ∼85 potential phosphorylation sites, which can be phosphorylated by various kinases because the unfolded structure of Tau makes them accessible. However, methodological limitations (e.g. in MS of phosphopeptides, or antibodies against phosphoepitopes) led to conflicting results regarding the extent of Tau phosphorylation in cells. Here we present results from a new approach based on native MS of intact Tau expressed in eukaryotic cells (Sf9). The extent of phosphorylation is heterogeneous, up to ∼20 phosphates per molecule distributed over 51 sites. The medium phosphorylated fraction Pm showed overall occupancies of ∼8 Pi (± 5) with a bell-shaped distribution; the highly phosphorylated fraction Ph had 14 Pi (± 6). The distribution of sites was highly asymmetric (with 71% of all P-sites in the C-terminal half of Tau). All sites were on Ser or Thr residues, but none were on Tyr. Other known posttranslational modifications were near or below our detection limit (e.g. acetylation, ubiquitination). These findings suggest that normal cellular Tau shows a remarkably high extent of phosphorylation, whereas other modifications are nearly absent. This implies that abnormal phosphorylations at certain sites may not affect the extent of phosphorylation significantly and do not represent hyperphosphorylation. By implication, the pathological aggregation of Tau is not likely a consequence of high phosphorylation.

16 July 2020

Deadly clashes at the border between Armenia and Azerbaijan have followed renewed disappointment in the peace process, and cast a new shadow over its future.

16 September 2020

The passing of a new family protection law is a major step forward for a country which has long suffered from high levels of hidden domestic abuse. But much work remains to be done in ensuring the principles it enshrines are translated to practical action and support for victims.

In addition to their well-known role in the control of cellular proliferation and cancer, cell cycle regulators are increasingly identified as important metabolic modulators. Several GWAS have identified SNPs near CDKN2A, the locus encoding for p16INK4a (p16), associated with elevated risk for cardiovascular diseases and type-2 diabetes development, two pathologies associated with impaired hepatic lipid metabolism. Although p16 was recently shown to control hepatic glucose homeostasis, it is unknown whether p16 also controls hepatic lipid metabolism. Using a combination of in vivo and in vitro approaches, we found that p16 modulates fasting-induced hepatic fatty acid oxidation (FAO) and lipid droplet accumulation. In primary hepatocytes, p16-deficiency was associated with elevated expression of genes involved in fatty acid catabolism. These transcriptional changes led to increased FAO and were associated with enhanced activation of PPARα through a mechanism requiring the catalytic AMPKα2 subunit and SIRT1, two known activators of PPARα. By contrast, p16 overexpression was associated with triglyceride accumulation and increased lipid droplet numbers in vitro, and decreased ketogenesis and hepatic mitochondrial activity in vivo. Finally, gene expression analysis of liver samples from obese patients revealed a negative correlation between CDKN2A expression and PPARA and its target genes. Our findings demonstrate that p16 represses hepatic lipid catabolism during fasting and may thus participate in the preservation of metabolic flexibility.

Eight ways to build better African cities The World Today mhiggins.drupal 2 August 2022

Young professionals from across the continent tell Emmanuel Adegboye how city life could be improved: from high-speed rail to people-centred urban planning.

Ahmed Elsawy, 33, Director of Talent
Cairo, Egypt
We must amend employment law in Egypt to support individual contractors to match with the global demand for short-term and project-based assignments within the tech and service industries. While we have a new, decent education system, I think we should care more about foreign languages to have a higher rank when it comes to the global competition of skilled workers.

Iman Abubaker, 31, Urban Mobility Project Manager, WRI Africa
Addis Ababa, Ethiopia
Rapid urbanization and increased motorization have exacerbated the city’s urban challenges. Addis Ababa would benefit from safer street design and people-centred city planning. Urban amenities should be located within walking and cycling distances. For longer trips, the city needs to invest in improving the accessibility, safety, integration and multimodality of its public transport system. I would love to see more pockets of green spaces and parks all around the city. 

Bree, 31, Project Manager
Nairobi, Kenya
I have a love-hate relationship with Nairobi. I spent four years smack in the middle of the city while attending the University of Nairobi. Being in the middle of all the hustle and bustle made the transition to a sleepy-ish coastal town easy. I would happily trade matatus [shared taxis] for tuktuks any day. I do miss the conveniences that come with a big city like a 24-hour grocery store and delivery services on those lazy days.

Mfon Bassey, 30, Co-Founder, TalentX Africa
Lagos, Nigeria
The government should improve the road networks and public transport systems, because the common challenge most Lagosians face is commuting from point A to B without traffic. There are so many private cars on the road because the public transport system isn’t optimally efficient yet. Once you take away the commute time most workers spend just to get work done, we’ll surely have happier Lagosians.

Olga Kiconco, 32, Innovation Strategist
Kampala, Uganda
As one of Africa’s fastest-growing cities with a projected 112 per cent population growth by 2035, there are a number of critical changes that need to be made in preparation for this. Our leaders should embrace coherent policies that will catalyze socio-economic transformation. We need to hold them accountable for better infrastructure and delivery of public services, while taking personal responsibility to protect our environment against the prevalent threat of climate change.

Etienne Amougou, 30, Curator/Arts Project Manager
Yaounde, Cameroon
What would make Yaounde better would be a good ecosystem that provides more opportunities for young people. If it was possible, I would like to see the creation of more cultural spaces, like parks, zoos, cinemas and sport areas. Also, we could use a more effective approach to waste management – sometimes we have trash everywhere in the ’hood.

Valentino Fernandez, 23, Writer
Johannesburg, South Africa
 We need better transportation to bridge the inequality gap and allow the youth to access spaces to be inspired and create change. Apartheid spatial planning is still affecting us. People of colour were relegated to the outskirts of the city, and very little has changed. It’s virtually impossible to move out of your childhood home, which means you’re looking at a two-hour commute every morning and two more hours to get home. I would like a reliable, affordable, high-speed rail system.

Jean-Louis Mbaka, 34, Co-Founder and Director, Education at Kinshasa Digital
Kinshasa, DRC
Our youth must receive a sufficient education that is in line with the strategic requirements of their future workplaces. By 2030, more than 130 million jobs in Africa will require digital skills, according to the International Finance Corporation. To close the gap between the conventional educational system and the labour market, our organisation is providing training for digital jobs. Initiatives like ours must be supported if the current and next generations are to have the means for their economic and social advancement. Scaling up investments in vital facilities like the internet is also necessary.

Africa Aware: Drought in the Horn of Africa Audio aboudiaf.drupal 31 October 2022

This episode discusses how the Horn of Africa’s worst drought in 40 years is affecting more than 20 million people across several countries.

Abdirahman Abdishakur, Special Presidential Envoy for Drought Response for the Federal Republic of Somalia, outlines the Somali government’s planning to prevent famine.

Parvin Ngala, Regional Director at Oxfam International, highlights international efforts to respond to the drought, the importance of empowering civil society in these circumstances, and what long-term mitigation measures are necessary to avoid a return to this situation.

Fighting over ‘white gold’: Sesame in Ethiopia and Sudan Expert comment LJefferson 3 April 2023

The supply chain of a seemingly innocuous cash crop – sesame – has intersected with transnational conflict dynamics, exacerbating tensions between Ethiopia and Sudan.

Late 2020 saw the beginning of the devastating war in Tigray and the occupation of a disputed region on the Ethiopia–Sudan border – Al Fashaga – by the Sudanese army. These shocks disrupted settled patterns of land ownership and control in both Ethiopia’s volatile north and Sudan’s borderlands, historically the heart of the sesame and oilseed production that is economically vital to both countries.

These seemingly harmless cash crops are now embedded in local, subnational and national political contestations in both countries. Sesame value chains are being reshaped, with power and profits being used to entrench the grip of political and armed actors who are reinforcing new patterns of land control and driving informal and illicit trade – impacting the coping mechanisms of local communities and threatening to fuel further conflict.

Regional rivalries drive contestation over the Ethiopia supply chain

Internal borders between most of Ethiopia’s regions are marked by boundary disputes, which often degenerate into violent conflict. The most important is between the Tigray and Amhara regions. Since the war began in 2020, the Amhara region has annexed vast areas of western and southern Tigray, which the Amhara region claims were taken from them by Tigray 30 years ago, after the Tigray People’s Liberation Front (TPLF) dominated ethnic coalition came to power.

Ethiopia’s exports of spices, oilseeds and pulses brought in over half a billion dollars in 2021, roughly a quarter of the country’s total export revenues and second only to coffee. The sector has been rocked by the war in the north, which accounted for much of Ethiopia’s sesame production, with an estimated 500,000 hectares of sesame fields taken out of cultivation during the 2021 growing season. Conflict has exacerbated a steady decline in formal revenues from sesame exports, dropping over $115 million from 2016 to 2021.

Alongside falling production, the previously integrated value chain has been disrupted and decentralized by political fragmentation and land competition between Amharas and Tigrayans. Before the war, the agricultural sector in Western Tigray/Welkait was dominated by Tigrayan business interests, through the TPLF’s regional endowment fund EFFORT, a business conglomerate including subsidiaries such as Guna Trading House, and Hiwot Agricultural Mechanization.