Geology and Geochemistry of the Chromiferous Mineralization in the External Zone of the Pan-African Dahomeyides Belt,Northwestern Benin(Gulf of Guinea,West Africa)

Occurrences of chromium mineral exist in Bénin within the external nappes of the Pan-African Dahomeyides belt. These chromite deposits are podiform types and hosted in the serpentinite. Blackish color, the chromite appears under microscope in transmitted light, as cracked phenocrystals with tangles of the serpentinite venules. Chemical analyses using X-ray fluorescence spectrometer showed the chromite ore consists of about 38% Cr2O3 and total (Cr2O3 + Al2O3) is 60%. This chromiferous mineralisation resulted from the magmatic cumulates formation by fractional crystallization of an ultramafic magma.

Modelling of the variation of granular base materials resilient modulus with material characteristics and humidity conditions

This study aims to quantify the susceptibility of granular materials used in pavements to changes in moisture content and propose a correlation model to incorporate this susceptibility into seasonal analyses.The fines content and the percentage of fractured coarse aggregates were identified as direct indicators of the resilient modulus susceptibility to changes in water content.The results showed that the percentage of fractured coarse aggregates particles(FR)has a more significant impact on the resilient modulus(Er)of crushed granular materials used in pavement construction than the combined indicator of the fines content and sample volumetrics(nf).Crushed granular materials with a higher percentage of fractured coarse aggregates are relatively insensitive to changes in the degree of saturation,but become more sensitive as the fine fraction porosity decreases.An adjusted model was proposed based on the existing formulation,but considers a complex parameter to describe and adjust the sensitivity of base granular materials to variations in moisture content with respect to fabrication charac-teristics,fines content and volumetric properties.The model shows that the variation of Er values is below10%for fully crushed granular materials.However,it reaches approximately±12%for materials with 75%of crushed coarse aggregates andþ40%and-25%for materials with FR=50%.This model could help select good ag-gregates characteristics and adjust grain-size distribution for environments where significant moisture content variations can occur in the pavement system,such as in the Province of Quebec(Canada).As it is based on pa-rameters that can be easily determined or estimated,it also represents a valuable tool for detailed design and analysis that can consider material characteristics.

Evaluation of a Rapid Diagnostic Test, Boson Biotech SARS CoV-2 Ag, for the Detection of SARS-CoV-2 in Gabon

1) Background: Rapid and acurate diagnostic testing for case identification, quarantine, and contact tracing is essential for managing the COVID 19 pandemic. Rapid antigen detection tests are available, however, it is important to evaluate their performances before use. We tested a rapid antigen detection of SARS-CoV-2, based on the immunochromatography (Boson Biotech SARS-CoV-2 Ag Test (Xiamen Boson Biotech Co., Ltd., China)) and the results were compared with the real time reverse transcriptase-Polymerase chain reaction (RT-PCR) (Gold standard) results;2) Methods: From November 2021 to December 2021, samples were collected from symptomatic patients and asymptomatic individuals referred for testing in a hospital during the second pandemic wave in Gabon. All these participants attending “CTA Angondjé”, a field hospital set up as part of the management of COVID-19 in Gabon. Two nasopharyngeal swabs were collected in all the patients, one for Ag test and the other for RT-PCR;3) Results: A total of 300 samples were collected from 189 symptomatic and 111 asymptomatic individuals. The sensitivity and specificity of the antigen test were 82.5% [95%CI 73.8 - 89.3] and 97.9 % [95%CI 92.2 - 98.2] respectively, and the diagnostic accuracy was 84.4% (95% CI: 79.8 - 88.3%). The antigen test was more likely to be positive for samples with RT-PCR Ct values ≤ 32, with a sensitivity of 89.8%;4) Conclusions: The Boson Biotech SARS-CoV-2 Ag Test has good sensitivity and can detect SARS-CoV-2 infection, especially among symptomatic individuals with low viral load. This test could be incorporated into efficient testing algorithms as an alternative to PCR to decrease diagnostic delays and curb viral transmission.

Molecular Detection of Resistance and Virulence Genes in Coagulase Negative Staphylococci Isolated from Blood Cultures at the University Teaching Hospital of Bouake

Introduction: Coagulase-negative staphylococci (CoNS) are currently recognized as genuine pathogens. However, little is known about the resistance and virulence genes that explain their pathogenicity in hospitals in Cte d'Ivoire. The aim of this study was to contribute to the genotypic identification of resistance and virulence genes in CoNS isolated from blood cultures at the University Teaching Hospital (CHU) of Bouak, in order to improve patient management. Material and Methods: This was a descriptive study conducted from September to December 2023. The CoNS isolates studied came from the collection of strains isolated from blood cultures of febrile patients hospitalized or attending consultations at the CHU of Bouak. The strains were analyzed using conventional simplex PCR. Results: Of the 45 isolates analyzed, 46.7% carried both the aacA-aphD and tetK genes and 40% carried the mecA gene. With regard to virulence genes, only the LukS-PV gene was observed in S. epidermidis and S. haemolyticus isolates. Conclusion: The high prevalence of CoNS isolates carrying the mecA gene and the presence of virulence genes observed in this study give cause for concern in hospitals. It is important to develop comprehensive surveillance strategies against nosocomial and multi-resistant infections at the CHU of Bouak.

Production of Yam Tubers Using Seed Tubers from Vitroplants Regenerated from Aerial Stems in the Yam Species Dioscorea alata (L.) and Dioscorea cayenensis-rotundata (L. & P.) in Côte d’Ivoire

The aim of this study is to produce large quantities of yam tubers in the field from seed tubers derived from vitroplants regenerated from aerial stem cuttings and farmers’ tuber seeds. Seed tubers from ten yam cultivars, including five from Dioscorea alata (cDa083, cDa053, cDa115, cDa150 and cDa266) and five from Dioscorea cayenensis-rotundata (cDr015, cDr027, cDr150, cDr206 and cDr148) with distinct agro-morphological characteristics, were used as material. A completely randomized block design with 3 replications was used. In each block, all cultivars and seed types were represented. When put into cultivation, the tubers produced by the vitroplants all germinated and gave 100% healthy plants, compared with 86% to 100% healthy plants for the seed tubers produced by the farmers. Yields per hectare ranged from 10 to 25 tonnes for seed tubers produced by in vitro plants, and from 4 to 9 tons for seed tubers produced by farmers. Seed tubers from vitroplants can therefore be recommended to farmers as a solution to the problem of seed tuber unavailability.

内蒙古北部苏尼特左旗蓝片岩岩石学和年代学研究

在苏尼特左旗以南地区的中古生代造山带的混杂岩带内发现了以岩块形式出现的蓝片岩 ,其矿物组合为斜长石 +阳起石 +蓝闪石 +绿帘石 +榍石。蓝片岩化学成分说明由基性火山岩变质而成。矿物化学分析表明 ,蓝片岩中角闪石可分为钙质、钙钠质和钠质 3类。钙质闪石均为阳起石 ,钙钠质闪石为蓝透闪石和冻蓝闪石 ,钠质闪石为蓝闪石和青铝闪石及少量镁钠闪石。利用Na(M4 )和AlⅣ 的含量推测本区钙质、钙钠质和钠质 3类闪石的压力从 0 3～ 0 7Gpa ,表明蓝片岩相变质作用的压力约为 0 7GPa。用化学反应限定蓝片岩的形成温度为 2 0 0～ 3 75℃左右。4 0 Ar 3 9Ar同位素年代学测定蓝闪石的等时线年龄为 3 83± 1 3Ma(1δ)。这些结果进一步证实沿贺根山—苏尼特左旗南是一条中古生代的缝合线 ,其俯冲—碰撞的标志即为混杂岩带以及其中的蓝片岩。

郯庐断裂带的两大发展阶段——广义的逆冲推覆断裂带和狭义的平移断裂带

笔者总结了近年来的研究成果认为,中国东部的郯庐断裂带自海西期以来经历了两个主要发展阶段:第一阶段是广义的郯庐断裂带发展阶段,晚三叠世—早侏罗世由于扬子地块与华北地块的碰撞,成为两地块的对接边界,具有逆冲推覆的性质,属广义的特提斯构造域。第二发展阶段从早白垩世以来,发展成为一条平移断裂带,属于狭义的环太平洋构造域的平移系统。岩相古地理资料显示了扬子地块与华北地块的对接始于晚二叠世早期;印支期的郯庐断裂带是一条由NE、NNE向展布的缓‘S’型的地块拼贴边界,在现今的郯庐断裂带上表现为残留的由北北西向南南东的斜向逆冲推覆的性质,中下构造层次表现为韧性逆冲推覆变形,上部构造层即前陆褶皱冲断带内的变形;应力场分析资料显示:早三叠世晚期开始地表浅部就有近南北向的挤压作用,左行走滑平移作用开始发育;早白垩世晚期开始转入引张伸展阶段,与中国东部的伸展作用一致;新近纪又转为近东西向挤压,发育逆冲兼右行走滑作用。

A Large-Scale Palaeozoic Dextral Ductile Strike-Slip Zone:the Aqqikkudug-Weiya Zone along the Northern Margin of the Central Tianshan Belt,Xinjiang,NW China

Abstract The nearly E-W-trending Aqqikkudug-Weiya zone, more than 1000 km long and about 30 km wide, is an important segment in the Central Asian tectonic framework. It is distributed along the northern margin of the Central Tianshan belt in Xinjiang, NW China and is composed of mylonitized Early Palaeozoic greywacke, volcanic rocks, ophiolitic blocks as a mélange complex, HP/LT-type bleuschist blocks and mylonitized Neoproterozoic schist, gneiss and orthogneiss. Nearly vertical mylonitic foliation and sub-horizontal stretching lineation define its strike-slip feature; various kinematic indicators, such as asymmetric folds, non-coaxial asymmetric macro- to micro-structures and C-axis fabrics of quartz grains of mylonites, suggest that it is a dextral strike-slip ductile shear zone oriented in a nearly E-W direction characterized by “flower” strusture with thrusting or extruding across the zone toward the two sides and upright folds with gently plunging hinges. The Aqqikkudug-Weiya zone experienced at least two stages of ductile shear tectonic evolution: Early Palaeozoic north vergent thrusting ductile shear and Late Carboniferous-Early Permian strike-slip deformation. The strike-slip ductile shear likely took place during Late Palaeozoic time, dated at 269±5 Ma by the40Ar/39Ar analysis on neo-muscovites. The strike-slip deformation was followed by the Hercynian violent S-type granitic magmatism. Geodynamical analysis suggests that the large-scale dextral strike-slip ductile shearing is likely the result of intracontinental adjustment deformation after the collision of the Siberian continental plate towards the northern margin of the Tarim continental plate during the Late Carboniferous. The Himalayan tectonism locally deformed the zone, marked by final uplift, brittle layer-slip and step-type thrust faults, transcurrent faults and E-W-elongated Mesozoic-Cenozoic basins.

Paleozoic Accretion-Collision Events and Kinematics of Ductile Deformation in the Eastern Part of the Southern-Central Tianshan Belt, China

The Tianshan range could have been built by both late Early Paleozoicaccretion and Late Paleozoic collision events. The late Early Paleozoic Aqqikkudug-Weiya suture ismarked by Ordovician ophiolitic melange and a Silurian flysch sequence, high-pressure metamorphicrelics, and mylonitized rocks. The Central Tianshan belt could principally be an Ordovician volcanicarc; whereas the South Tianshan belt, a back-arc basin. Macro- and microstructures, along withunconformities, provide some kinematic and chronological constraints on 2-phase ductile deformation.The earlier ductile deformation occurring at ca. 400 Ma was marked by north-verging ductileshearing, yielding granulite-bearing ophiolitic melange blocks and garnet-pyroxene-facies ductiledeformation, and the later deformation, a dextral strike-slip tectonic process, occurred during theLate Carboniferous-Early Permian. Early Carboniferous molasses were deposited unconformably onpre-Carboniferous metamorphic and ductilely sheared rocks, implying the end of the early orogeny.The large-scale ductile strike-slip along the Aqqikkudug-Weiya zone was possibly caused by thesecond tectonic event, the Hercynian collision between the northern Tarim block and the southernSiberian block. Late Paleozoic granitic magmatism and superimposed structures overprinted this EarlyPaleozoic deformation belt. Results of geometric and kinematic studies suggest that the primaryframework of the Southern-Central Tianshan belt, at least the eastern part of the Tianshan belt, wasbuilt by these two phases of accretion events.

Geochemical Features of the Two Early Paleozoic Ophiolitic Zones and Volcanic Rocks in the Central-Southern Tianshan Region, Xinjiang

This paper deals with the geochemical features of the two Early Paleozoic ophiolite zones in the central\|southern Tianshan region and the central Tianshan igneous rock belt between them. Study results suggest that the central Tianshan belt was an Ordovician volcanic arc with an affinity of continental crust, and the Kumux\|Hongliuhe ophiolitic zone that is located on the southern margin of central Tianshan has a crustal affinity to back\|arc marginal sea. The Aqqikkudug\|Weiya ophiolitic zone is an accretionary boundary between the Tuha continental block and the central Tianshan volcanic arc during Late Silurian to Devonian; Ordovician ophiolitic blocks, Silurian flysch sequence and HP metamorphic rock relics are distributed along the Aqqikkudug\|Weiya zone. Geochemically, ophiolitic rocks in the Aqqikkudug\|Weiya zone have an affinity to oceanic crust, reflecting a tectonic setting of paleo\|trench or subduction zone. The Early Carboniferous red molasses were deposited unconformably on the pre\|Carboniferous metamorphosed and ductile sheared volcanic and flysch rocks, providing an upper limit age of the central and southern Tianshan belts.

Late syn-to post-collisional magmatism in Madagascar:The genesis of the Ambalavao and Maevarano Suites

The East African Orogen involves a collage of Proterozoic microcontinents and arc terranes that became wedged between older cratonic blocks during the assembly of Gondwana.The Ediacaran-Cambrian Ambalavao and Maevarano Suites in Madagascar were emplaced during the waning orogenic stages and consist of weakly deformed to undeformed plutonic rocks and dykes of mainly porphyritic granite but also gabbro,diorite and charnockite.U-Pb geochronological data date emplacement of the Ambalavao Suite to between ca.580 Ma and 540 Ma and the Maevarano Suite to between ca.537 Ma and522 Ma.Major and trace element concentrations are consistent with emplacement in a syn-to postcollisional tectonic setting as A-type(anorogenic) suites.Oxygen(δ^(18)O of 5.27‰-7.45‰) and hafnium(ε(Hf)(t) of-27.8 to-12.3) isotopic data from plutons in the Itremo and Antananarivo Domains are consistent with incorporation of an ancient crustal source.More primitive δ^(18)O(5.27‰-5.32‰) andε(Hf)(t)(+0.0 to+0.2) isotopic values recorded in samples collected from the Ikalamavony Domain demonstrate the isotopic variation of basement sources present in the Malagasy crust.The Hf isotopic composition of Malagasy zircon are unlike more juvenile Ediacaran-Cambrian zircon sou rces elsewhere in the East African Orogen and,as such,Madagascar represents a distinct and identifiable detrital zircon source region in Phanerozoic sedimentary provenance studies.Taken together,these data indicate that high-T crustal anatexis,crustal assimilation and interaction of crustal material with mantle-derived melts were the processes operating during magma emplacement.This magmatism was coeval with polyphase deformation throughout Madagascar during the amalgamation of Gondwana and magmatism is interpreted to reflect lithospheric delamination of an extensive orogenic plateau.

Characteristics and potential analysis of Madagascar hydrocarbon-bearing basins

Madagascar becomes a large isolated island after its dislocation from East Africa at its western part during the opening of the Mozambique Channel and its separation from India at its eastern part during the opening of the basin of the Mascarene. From a stratigraphic point of view, Karroo of Madagascar shares substantial similarities with the stratigraphic strata of East Africa.While oil companies have taken a liking to the basins of East Africa, they also turn to the basins in the western part of Madagascar especially after the discovery of large oil fields at Tsimiroro and Bemolanga. According to the study of their geological history, the basins of Madagascar contain huge hydrocarbon potential. The western basins, which is more developed than the east coast of the island, have been the subject of many in-depth studies by numerous researchers. The cross-referencing of bibliographic data with geological studies, and knowledge of hydrocarbon formation and maturation stages, carried out in this study served to determine the nature of source rocks, reservoir rocks, bedrock and eventual trapping system of hydrocarbons in Madagascar. This study identified the properties of Madagascar source rocks, reservoir rocks, bedrock and the final oil and gas trap system by cross-referencing the literature and geological research, oil and gas formation and maturity stages, and shows that Madagascar has considerable hydrocarbon potential.

How can the forest sector mitigate climate change in a changing climate? Case studies of boreal and northern temperate forests in eastern Canada

Background:Forest based climate mitigation emerged as a key component of the Paris Agreement,and thus re-quires robust science to reduce uncertainties related to such strategies.The aim of this study was to assess and compare the cumulative effects on carbon dynamics of forest management and climate change on boreal and northern temperate forest sector in eastern Canada for the 2020–2100 period.Methods:We used the spatially explicit forest landscape model LANDIS-II and its extension Forest Carbon Suc-cession,in conjunction with the Carbon Budget Model for Harvested Wood Products framework.We simulated the dynamics of forest composition and carbon flows from forest ecosystems to wood products and their substitution effect on markets under increasing climate forcing,according to a tonne-year approach.Simulations were con-ducted for a series of forest management scenarios based on realistic practices principally by clearcut in the boreal territory and continuous-cover forestry in the northern temperate one.These scenarios included:i)a business-as-usual scenario(BaU),representing the current management strategy,ii)increased harvesting by 6.3%to 13.9%,iii)increased conservation(i.e.reduced harvesting by 11.1%to 49.8%),iiii)and a scenario representing the natural evolution of the forest landscape(i.e.without any management activity).Results:Our study revealed that increasing harvesting levels had contrasting effects on the mitigation potential in northern temperate(enhance net sequestration)and boreal forest sector(enhance net emissions)in comparison to the BaU from 2040 onwards,regardless of the future climate.Carbon storage in wood products and the substi-tution effect were not sufficient to offset carbon emissions from ecosystems.Moreover,climate change had a strong impact on the capacity of both landscapes to act as carbon sinks.Northern temperate landscapes became a net source of carbon over time due to their greater vulnerability to climate change than boreal landscapes.Conclusions:Our study highlights the need to consider the initial landscape characteristics in simulations to maximize the mitigation potential of alternative forest management strategies.The optimal management solution can be very different according to the characteristics of forest ecosystems.This opens the possibility of optimizing management for specific forest stands,with the objective of maximizing the mitigation potential of a given landscape.

Geochemistry of the volcanic rocks from Bioko Island(“Cameroon Hot Line”)： Evidence for plume-lithosphere interaction

Bioko Island（3008 m a.s.l） is located in the presently more active volcanic zone of the Cameroon Line and composed essentially of alkaline basalts and hawaiites, and lesser mugearites. The rocks show microlitic porphyritic texture with phenocrysts of olivine（83% 〈 Fo 〈 87%） and clinopyroxene in a matrix of plagioclase, clinopyroxene and oxides. Hawaiites and mugearites also include phenocrysts of plagioclase（An62-67Ab35-32Or3-1）. Major element variation diagrams show an increase in Si O2, Al2O3, Na2 O and K2 O with increasing Mg O for the studied rock groups. The rocks are characterized by low（^86Sr/^87Sr）i ratios（0.70320e0.70406）, high 3Nd（t） values（2.56e4.33） and high（^206Pb/^204Pb）i ratios（20.032e20.035） values.Basalts are enriched in LILE and LREE, and have（Hf/Sm）N= 0.57e1.16. These geochemical signatures are similar to those of the Mount Cameroon rocks, and might be attributed to low degrees of partial melting from a garnet-amphibole-bearing mantle source. The trace elements and isotopic compositions suggest that the parental magma source might have involved HIMU- and EM1-components.

Aptian-Late Cenomanian Fluvio-Lacustrine Lithofacies and Palynomorphs from Mamfe Basin, Southwest Cameroon, West Africa

The sedimentary sequences in the Mamfe Basin are generally thought of as continental (fluvio-lacustrine) in origin. But the wide spread occurrence of salt springs and salt accumulations and in places gypsum, often puts to question the exclusive continentality throughout this basin’s history. The sequences studied portray a wide range of complex lithologies and lithofacies relationships and include basal and intra-formational conglomerates, sandstones, shales, carbonaceous, carbonate and halite facies respectively. All these are well exposed at several outcrop sections distributed all over the basin with some measuring up to and above 30 m in height.?Sedimentary structures include: parallel aligned imbricated prismatic pebbles, plannar to trough-cross stratifications, fining upward grain size distribution and thin frequently alternating sandstone-shale beds. Palynological data have been obtained for the first time from the shally and carbonate intervals and integrated with five lithofacies associations, permitting the determination of the ages and paleo environmental reconstruction. The palynomorphs are characterized by pteridophytic spores dominated by?Cicatricosisporites?sp.,Cyathidites?sp. and?Deltoidspora?sp., pollen grains include gymnosperms dominated by?Classopollis annulatus?and?Classopollis todosus?and angiosperms represented by?Retitricolpites?sp. and?Retimoncolpites?sp., fungal remains include some hyphae and?Fusiformisporites?sp. Only a few dinoflagellate cysts dominantly?Spiniferites?were encountered at Nfaitok outcrop, suggesting a proximal sea water influence. A fluvial, lacustrine-deltaic and an anoxic deep bottom lake setting sub-environments were reconstructed with no marine strata encountered. The brines are here suggested to have originated from sea water splay over a barrier and complimented by the chemistry of the drained surrounding country rocks. The palynomorph assemblage suggests an Aptian-Turonian age for the studied sequences and a chronostratigraphic sequence in which the Nfaitok and Satom Bridge units are both Late Cenomanian-Turonian (lateral equivalents of each other) are younger and overlie the Aptian-Early-Cenomanian Okoyong sandstone unit.

Pigs receiving daily tailored diets using precision-feeding techniques have different threonine requirements than pigs fed in conventional phase-feeding systems

Background: There is large variation in amino acids requirements among pigs,hence feeding pigs individually with daily tailored diets or in groups with a single feed may require different levels of nutrients.Thus,the response to different threonine levels(70%,85%,100%,115%,and 130% of the ideal threonine:lysine protein ratio of 0.65) was studied in growing pigs raised in a conventional group phase-feeding(GPF) system or fed individually using individual precision-feeding(IPF) techniques.In a 21-day trial,110 barrows(25 ± 0.80 kg body weight) were housed in the same room and fed using electronic feeders.Five pigs per treatment were slaughtered at the end of the trial.Results: Threonine intake increased linearly for the IPF and GPF pigs(P < 0.05).Lysine intake was similar across the treatments.Average daily gain,gain:feed ratio,and protein deposition were affected linearly by threonine level(P < 0.05)in both feeding systems.Protein deposition in the GPF pigs was maximized at 150 g/d and a 0.65 threonine:lysine ratio,whereas protein deposition increased linearly in the IPF pigs.Plasma Met and serine levels were 11 and 7% higher,respectively,in the IPF pigs than in the GPF pigs(P < 0.05).Dietary threonine increased(P < 0.05)threonine concentration in the longissimus dorsi in a quadratic manner in the IPF pigs,whereas there was no effect in the GPF pigs.Longissimus dorsi collagen decreased as dietary threonine increased in the IPF and GPF pigs(P < 0.10).Carcass muscle crude protein was 2% higher in the GPF pigs than in the IPF pigs(P < 0.05).Conclusions: Individual pigs are able to modulate growth and the composition of growth according to threonine intake.The average amino acid ratio value that is currently used for GPF cannot be used for IPF.

Haplotype-resolved genome assembly and allele- specific gene expression in cultivated ginger

Ginger(Zingiber officinale)is one of the most valued spice plants worldwide;it is prized for its culinary and folk medicinal applications and is therefore of high economic and cultural importance.Here,we present a haplotype-resolved,chromosome-scale assembly for diploid ginger anchored to 11 pseudochromosome pairs with a total length of 3.1 Gb.Remarkable structural variation was identified between haplotypes,and two inversions larger than 15Mb on chromosome 4 may be associated with ginger infertility.We performed a comprehensive,spatiotemporal,genome-wide analysis of allelic expression patterns,revealing that most alleles are coordinately expressed.The alleles that exhibited the largest differences in expression showed closer proximity to transposable elements,greater coding sequence divergence,more relaxed selection pressure,and more transcription factor binding site differences.We also predicted the transcription factors potentially regulating 6-gingerol biosynthesis.Our allele-aware assembly provides a powerful platform for future functional genomics,molecular breeding,and genome editing in ginger.

Spinel-Bearing Lherzolite Xenoliths from Hossere Garba(Likok,Adamawa-Cameroon):Mineral Compositions and Geothermobarometric Implications

Spinel-bearing lherzolite xenoliths from the Hossere Garba (1272 m.a.s.l) volcano on the Adamawa Plateau, is located in Likok village, at about 35 km to WSW of Ngaoundere. These xenoliths (~11 cm size) have been sampled into the host basaltic lava flows from the NE flank of the Hossere Garba volcano. These xenoliths characterized by porphyroclastic texture consisted of olivine (~55 vol.%), orthopyroxene (~19 vol.%) and clinopyroxene (~21 vol.%) crystals. Spinel crystals (~5 vol.%) are red brown and interstitial between the crystals of olivine and pyroxenes. CaO contents are low (<0.08 wt%) in olivine and similar to those estimated (CaO: 0.05 - 0.1 wt%) for the mantle origin. The values of AlVI/AlIV ratio range between 1.1 and 1.3 for the Cr-diopside crystals from Hossere Garba xenoliths. The constant value of the volumes V(Cell) and V(M1) for clinopyroxene compositions, indicates the similar pressures. Hossere Garba represents a residual sequence issued from partial melting of a mantle source. Similar compositions have been recorded in minerals of ultramafic xenoliths from other ultramafic xenoliths domains of the Cameroon Line and the Adamawa Plateau.

Phylogeny of the Order Bacillales inferred from 3’16S rDNA and 5’16S-23S ITS nucleotide sequences

A short 220 bp sequence was used to study the taxonomic organization of the bacterial Order Bacillales. The nucleotide sequences of the 3’ end of the 16S rDNA and the 16S-23S Internal transcribed spacer (ITS) were determined for 32 Bacillales species and strains. The data for 40 additional Bacillales species and strains were retrieved directly from Genbank. Together, these 72 Bacillales species and strains encompassed eight families and 21 genera. The 220 bp se- quence used here covers a conserved 150 bp sequence located at the 3’ end of the 16S rDNA and a conserved 70 bp sequence located at the 5’ end of the 16S-23S ITS. A neighbor-joining phylogenetic tree was inferred from comparative analyses of all 72 nucleotide sequences. Eight major Groups were revealed. Each Group was sub-divided into sub-groups and branches. In general, the neighbor-joining tree presented here is in agreement with the currently accepted phylogeny of the Order Bacillales based on phenotypic and genotypic data. The use of this 220 bp sequence for phylogenetic analyses presents several advantages over the use of the entire 16S rRNA genes or the generation of extensive phenotypic and genotypic data. This 220 bp sequence contains 150 bp at the 3’ end of the 16S rDNA which allows discrimination among distantly related species and 70 bp at the 5’ end of the 16S-23S ITS which, owing to its higher percentage of nucleotide sequence divergence, adds discriminating power among closely related species from same genus and closely related genera from same family. The method is simple, rapid, suited to large screening programs and easily accessible to most laboratories.

Chromosome-scale assembly and evolution of the tetraploid Salvia splendens (Lamiaceae) genome

Polyploidization plays a key role in plant evolution,but the forces driving the fate of homoeologs in polyploid genomes,i.e.,paralogs resulting from a whole-genome duplication(WGD)event,remain to be elucidated.Here,we present a chromosome-scale genome assembly of tetraploid scarlet sage(Salvia splendens),one of the most diverse ornamental plants.We found evidence for three WGD events following an older WGD event shared by most eudicots(theγevent).A comprehensive,spatiotemporal,genome-wide analysis of homoeologs from the most recent WGD unveiled expression asymmetries,which could be associated with genomic rearrangements,transposable element proximity discrepancies,coding sequence variation,selection pressure,and transcription factor binding site differences.The observed differences between homoeologs may reflect the first step toward sub-and/or neofunctionalization.This assembly provides a powerful tool for understanding WGD and gene and genome evolution and is useful in developing functional genomics and genetic engineering strategies for scarlet sage and other Lamiaceae species.