Investigation of the Architecture and Age of Superlative Adansonia grandidieri from the Andombiry Forest, Madagascar

Over the past years, our research on baobabs mainly focused on the largest Malagasy species, namely the Reniala or Grandidier baobab (Adansonia grandidieri Baill.). The biggest A. grandidieri are located in the Morombe area, especially in the so-called Andombiry Forest. This giant forest of Reniala hosts well over 6000 mature individuals, out of which more than 30 have very large sizes, i.e., circumferences over 20 m. We investigated, measured and dated by AMS radiocarbon the largest specimens. We found that all large Grandidier baobabs are multi-stemmed. They mostly exhibit a closed ring-shaped structure, with a false cavity inside. In this architecture, which enables Grandidier baobabs to reach very large sizes, the stems that build the ring typically have similar ages. Here we present the AMS radiocarbon investigation of two large baobabs, A 215 (girth 21.50 m) and A 257 (girth 25.70 m). According to dating results, the baobab A 215 has an age of only 375 years. It consists of four fused stems and has a closed ring-shaped structure. The baobab A 257 has the second largest trunk of all known live Reniala trees. It also exhibits a closed ring-shaped structure, with five fused stems around a false cavity, which has an opening toward the exterior. The dating results indicate that A 257 is around 900 years old.

Macrophage aggresome-like induced structures are flexible organizing platforms for immune signaling

ABSTRACTMacrophages adopt a pro-inflammatory phenotype in response to environmental challenges in a process that often coincides with the formation of transient cytosolic p62/SQSTM1 inclusions containing ubiquitinated proteins in structures known as aggresome-like induced structures (ALIS). Although described as stress-induced inclusions that accumulate aggregated proteins, little direct evidence supports their hypothesized structural role in the context of immune stimulation. Here, we showed that these structures in primary macrophages are induced by multiple microbialbased ligands, including exposure to cytosolic double-stranded DNA. Rather than accumulating aggregated proteins, we observed that ubiquitinated proteins form a ring-shaped structure around the perimeter of these circular foci. We identified that different microbial stimuli induced the formation of ubiquitin-positive foci with distinct characteristics and we observed selective recruitment of context-dependent immune regulators. Our findings are consistent with a model where these ubiquitin-containing structures act as adaptable organizing centers for innate immune signaling.SUMMARYCharbonneau et al. demonstrate that ubiquitin- and p62-containing cytosolic ring-shaped structures induced by bacterial infections, microbial ligands and cytosolic double-stranded DNA contain context-dependent immune regulators, revealing an important insight on the cellular architecture required to coordinate signal transduction in macrophage.

Compact CPW-fed super wideband planar elliptical antenna

A compact co-planar waveguide (CPW) fed planar elliptical antenna has been designed and presented for super wideband (SWB) characteristics. The designed antenna has an overall size of 30 × 30 × 1.57 mm3, and it consists of an elliptical patch radiator fed using a modified 50 Ω CPW-fed tapered microstrip feed line. By using a semi-ring shaped structure with a tapered feed line, an impedance bandwidth of 180.66% has been observed from 1.27 to 25 GHz with a ratio bandwidth of 19.68:1. To validate simulation results, the designed antenna has been fabricated and measured, and a reasonable agreement has been observed between simulated and measured results. It has also been observed that the designed antenna offers good radiation properties over the entire operating bandwidth. The simulated average gain and radiation efficiency of the proposed SWB antenna is noted to be 4.3 dBi and 95.77%, respectively; while the measured average gain and radiation efficiency is 3.8 dBi and 94.69%, respectively.

Age and architecture of the largest African Baobabs from Mayotte, France

The volcanic Comoro Islands, located in the Indian Ocean in between mainland Africa and Madagascar, host several thousand African baobabs (Adansonia digitata). Most of them are found in Mayotte, which currently belongs to France, as an overseas department. Baobabs constitute a reliable archive for climate change and millennial specimens were recently used as proxies for paleoclimate reconstructions in southern Africa. We report the investigation of the largest two baobabs of Mayotte, the Big baobab of Musical Plage and the largest baobab of Plage N’Gouja. The Big baobab of Musical Plage exhibits a cluster structure and consists of 5 fused stems, out of which 4 are common stems and one is a false stem. The baobab of Plage N’Gouja has an open ring-shaped structure and consists of 7 partially fused stems, out of which 3 stems are large and old, while 4 are young. Several wood samples were collected from both baobabs and analyzed via radiocarbon dating. The oldest dated sample from the baobab of Musical Plage has a radiocarbon date of 275 ± 25 BP, which corresponds to a calibrated calendar age of 365 ± 15 yr. On its turn, the oldest sample from Plage N’Gouja has a radiocarbon date of 231 ± 20 BP, corresponding to a calibrated age of 265 ± 15 yr. These results indicate that the Big baobab of Musical Plage is around 420 years old, while the baobab of Plage N’Gouja has an age close to 330 years. In present, both baobabs are in a general state of deterioration with many broken or damaged branches, and the Baobab of Plage N’Gouja has several missing stems. These observations suggest that the two baobabs are in decline and, most likely, close to the end of their life cycle.

Age and architecture of the largest African Baobabs from Mayotte, France

The volcanic Comoro Islands, located in the Indian Ocean in between mainland Africa and Madagascar, host several thousand African baobabs (Adansonia digitata). Most of them are found in Mayotte, which currently belongs to France, as an overseas department. We report the investigation of the largest two baobabs of Mayotte, the Big baobab of Musical Plage and the largest baobab of Plage N’Gouja. The Big baobab of Musical Plage exhibits a cluster structure and consists of 5 fused stems, out of which 4 are common stems and one is a false stem. The baobab of Plage N’Gouja has an open ring-shaped structure and consists of 7 partially fused stems, out of which 3 stems are large and old, while 4 are young. Several wood samples were collected from both baobabs and analyzed via radiocarbon dating. The oldest dated sample from the baobab of Musical Plage has a radiocarbon date of 275 ± 25 BP, which corresponds to a calibrated calendar age of 365 ± 15 yr. On its turn, the oldest sample from Plage N’Gouja has a radiocarbon date of 231 ± 20 BP, which translates into a calibrated age of 265 ± 15 yr. These results indicate that the Big baobab of Musical Plage is around 420 years old, while the baobab of Plage N’Gouja has an age close to 330 years. In present, both baobabs are in a general state of deterioration with many broken or damaged branches, and the Baobab of Plage N’Gouja has several missing stems. These observations suggest that the two baobabs are in decline and, most likely, close to the end of their life cycle.

Bacteriophage SP01 Gene Product 56 (gp56) Inhibits Bacillus subtilis Cell Division by Interacting with DivIC/FtsL to Prevent Pbp2B/FtsW Recruitment

ABSTRACTPrevious work identified gp56, encoded by the lytic bacteriophage SP01, as responsible for inhibition of Bacillus subtilis cell division during its infection. Assembly of the essential tubulin-like protein FtsZ into a ring-shaped structure at the nascent site of cytokinesis determines the timing and position of division in most bacteria. This FtsZ ring serves as a scaffold for recruitment of other proteins into a mature division-competent structure permitting membrane constriction and septal cell wall synthesis. Here we show that expression of the predicted 9.3-kDa gene product 56 (gp56) of SP01 inhibits latter stages of B. subtilis cell division without altering FtsZ ring assembly. GFP-tagged gp56 localizes to the membrane at the site of division. While its localization permits recruitment of early division proteins, gp56 interferes with the recruitment of late division proteins, including Pbp2b and FtsW. Imaging of cells with specific division components deleted or depleted and two-hybrid analysis suggest that gp56 localization and activity depends on its interaction with mid-recruited proteins DivIC and/or FtsL. Together these data support a model where gp56 interacts with a central part of the division machinery to disrupt late recruitment of the division proteins involved in septal cell wall synthesis.IMPORTANCEResearch over the past decades has uncovered bacteriophage-encoded factors that interfere with host cell shape or cytokinesis during viral infection. Phage factors that cause cell filamentation that have been investigated to date all act by targeting FtsZ, the conserved prokaryotic tubulin homolog that composes the cytokinetic ring in most bacteria and some groups of archaea. However, the mechanism of several identified phage factors that inhibit cytokinesis remain unexplored, including gp56 of bacteriophage SP01 of Bacillus subtilis. Here, we show that unlike related published examples of phage inhibition of cyotkinesis, gp56 blocks B. subtilis cell division without targeting FtsZ. Rather, it utilizes the assembled FtsZ cytokinetic ring to localize to the division machinery and block recruitment of proteins needed for the septal cell wall synthesis.

Age, Growth and Death of a National Icon: The Historic Chapman Baobab of Botswana

The year 2016 witnessed the fall of a symbol of the botanical world: the historic Chapman baobab of Botswana. This article presents the results of our investigation of the standing and fallen tree. The Chapman baobab had an open ring-shaped structure composed of six partially fused stems. Several wood samples collected from the stems prior and after their collapse were analysed by using radiocarbon dating. The radiocarbon date of the oldest sample was 1381 ± 22 BP, which corresponds to a calibrated age of 1345 (+10, −15) calendar years. The dating results show that the six stems of the Chapman baobab belonged to three different generations, which were 1350–1400, 800–1000 and 500–600 years old. The growth rate variation of the largest and oldest stem is presented and correlated with the climate evolution in the area over the past 1000 years. The factors that determined the sudden fall and death of the Chapman baobab are also presented and discussed.

γ-Tubulin–γ-Tubulin Interactions as the Basis for the Formation of a Meshwork

In cytoplasm, protein γ-tubulin joins with various γ-tubulin complex proteins (GCPs) to form a heterotetramer γ-tubulin small complex (γ-TuSC) that can grow into a ring-shaped structure called the γ-tubulin ring complex (γ-TuRC). Both γ-TuSC and γ-TuRC are required for microtubule nucleation. Recent knowledge on γ-tubulin with regard to its cellular functions beyond participation in its creation of microtubules suggests that this protein forms a cellular meshwork. The present review summarizes the recognized functions of γ-tubulin and aims to unite the current views on this protein.

Extreme jet distortions in low-z radio galaxies

Jets often display bends and knots at which the flows change character. Extreme distortions have implications for the nature of jet flows and their interactions. We present the results of three radio mapping campaigns. The distortion of 3CRR radio galaxy NGC 7385 is caused by a collision with a foreground magnetised gas cloud which causes Faraday rotation and free-free absorption, and is triggered into star formation. For NGC 6109 the distortion is more extreme, creating a ring-shaped structure, but no deflector can be identified in cold or hot gas. Similar distortions in NGC 7016 are apparently associated with an X-ray gas cavity, and the adjacent NGC 7018 shows filaments drawn out beyond 100 kpc. Encounters with substructures in low-density, magnetised, intergalactic gas are likely causes of many of these features.