SEASONAL HEAT BUDGET IN THE TROPICAL WESTERN PACIFIC OCEAN IN A GLOBAL GCM Ⅱ. IN FIVE SUBREGIONS

The general features of the seasonal suuface heat budget in the tropical western Pacific Ocean,20°S-20°N, western boundary-160°E, were documented by Qu (1995) using a high-resolution generalcirculation model (GCM, Semtner & Chervin,1992) ard existing observations.Close inspection of thesmaller areas, with the whole region further partitioned into six parts, showed different mechanisms balancethe seasonal surface heat budget in different parts of the region The results of study on five subregionsare detailed in this article. In the equatorial (3°S - 3°N) aed North Equatorial Countercurrent(3°N-9°N) region, the surface the flux the does not change significantly throughout the year, so the surface heat content is determined largely by vertical motion near the equator and roughly helf due to horizontal and halfdue to vertical circulation in the region of the North Equatorial Countercurrent(NECC). In the othersubregions (9°N-20°N, 20°S -11°S aed 11°S -3°S ), however, in addition to ocean

A high-performance liquid chromatography with fluorescence detection method for the simultaneous quantitation of monoamine neurotransmitters and their metabolites in subregions of rat brain

Abstract： In the presem study, we simultaneously quantified the levels of monoamine neurotransmitters （MANTs） and their metabolites （levodopa, norepinephrine, epinephrine, dopamine, 5-HT, 3,4-dihydroxyphenylacetic acid, homovanillic acid and 5-hydroxyindole-3-acetic acid） in different brain subregions of rats using a newly developed simple, sensitive and selective high-performance liquid chromatography with fluorescence detection （HPLC-FLD） method. In this new HPLC-FLD method, analytes were directly extracted and separated without deriveatization step within 20 min. The FLD wavelength was set at 280 nm and 330 nm for excitation and emission, respectively. The analytes were separated on an Agilent Eclipse Plus Cls column （4.6 mm×150 mm, 5.0 μm） equipped with an Agilent XDB-C18 security guard column （4.6 mm×12.5 mm, 5.0 lam）, and the column temperature was maintained at 35 ℃. The mobile phase for elution was isocratic. The mobile phase consisted of citric acid buffer （50 mmol/L citric acid, 50 mmol/L sodium acetate, 0.5 mmol/L octane sulfonic acid sodium salt, 0.5 mmol/L Na2EDTA and 5 mmol/L triethylamine, pH 3.8） and methanol （90：10, v/v） at a flow rate of 1.0 mL/min. The detection limit （DL） was 0.9-23 nM for all the MANTs and their metabolites with a sample volume of 50 μL. The method was shown to be highly reproducible in terms of peak area （intraday, 0.08%-1.85% RSD, n = 5）. The simultaneous measurement of these MANTs and their metabolites improved our understanding of the neurochemistry in the central nervous system （CNS） in relation to different addictive drugs （methamphetamine, heroin and their mixture） in drug-addicted rat models.

Altered functional connectivity networks of hippocampal subregions in remitted late-onset depression:a longitudinal resting-state study

The regional specifi city of hippocampal abnormalities in late-life depression（LLD） has been demonstrated in previous studies. In this study,we sought to examine the functional connectivity（FC） patterns of hippocampal subregions in remitted late-onset depression（r LOD）,a special subtype of LLD. Fourteen r LOD patients and 18 healthy controls underwent clinical and cognitive evaluations as well as resting-state functional magnetic resonance imaging scans at baseline and at ~21 months of follow-up. Each hippocampus was divided into three parts,the cornu ammonis（CA）,the dentate gyrus,and the subicular complex,and then six seed-based hippocampal subregional networks were established.Longitudinal changes of the six networks over time were directly compared between the rL OD and control groups. From baseline to follow-up,the r LOD group showed a greater decline in connectivity of the left CA to the bilateral posterior cingulate cortex/precuneus（PCC/PCUN）,but showed increased connectivity of the right hippocampal subregional networks with the frontal cortex（bilateral medial prefrontal cortex/anterior cingulate cortex and supplementary motor area）. Further correlative analyses revealed thatthe longitudinal changes in FC between the left CA and PCC/PCUN were positively correlated with longitudinal changes in the Symbol Digit Modalities Test（r = 0.624,P = 0.017） and the Digit Span Test（r = 0.545,P = 0.044） scores in the r LOD group. These results may provide insights into the neurobiological mechanism underlying the cognitive dysfunction in r LOD patients.

Iterative Subregion Correction Preconditioners with Adaptive Tolerance for Problems with Geometrically Localized Stiffness

We present a class of preconditioners for the linear systems resulting from a finite element or discontinuous Galerkin discretizations of advection-dominated problems.These preconditioners are designed to treat the case of geometrically localized stiffness,where the convergence rates of iterative methods are degraded in a localized subregion of the mesh.Slower convergence may be caused by a number of factors,including the mesh size,anisotropy,highly variable coefficients,and more challenging physics.The approach taken in this work is to correct well-known preconditioners such as the block Jacobi and the block incomplete LU(ILU)with an adaptive inner subregion iteration.The goal of these preconditioners is to reduce the number of costly global iterations by accelerating the convergence in the stiff region by iterating on the less expensive reduced problem.The tolerance for the inner iteration is adaptively chosen to minimize subregion-local work while guaranteeing global convergence rates.We present analysis showing that the convergence of these preconditioners,even when combined with an adaptively selected tolerance,is independent of discretization parameters(e.g.,the mesh size and diffusion coefficient)in the subregion.We demonstrate significant performance improvements over black-box preconditioners when applied to several model convection-diffusion problems.Finally,we present performance results of several variations of iterative subregion correction preconditioners applied to the Reynolds number 2.25×10^(6)fluid flow over the NACA 0012 airfoil,as well as massively separated flow at 30°angle of attack.

Effect of hyperthermia on calbindin-D 28k immunoreactivity in the hippocampal formation following transient global cerebral ischemia in gerbils

Calbindin D-28K （CB）, a Ca2＋-binding protein, maintains Ca2＋ homeostasis and protects neurons against various insults. Hyperthermia can exacerbate brain damage produced by ischemic insults. However, little is reported about the role of CB in the brain under hyperthermic condition during ischemic insults. We inves- tigated the effects of transient global cerebral ischemia on CB immunoreactivity as well as neuronal damage in the hippocampal formation under hyperthermic condition using immunohistochemistry for neuronal nuclei （NeuN） and CB, and Fluoro-Jade B histofluorescence staining in gerbils. Hyperthermia （39.5 ＋ 0.2~C） was induced for 30 minutes before and during transient ischemia. Hyperthermic ischemia resulted in neu- ronal damage/death in the pyramidal layer of CA1-3 area and in the polymorphic layer of the dentate gyrus at 1, 2, 5 days after ischemia. In addition, hyperthermic ischemia significantly decreaced CB immunoreac- tivity in damaged or dying neurons at 1, 2, 5 days after ischemia. In brief, hyperthermic condition produced more extensive and severer neuronal damage/death, and reduced CB immunoreactivity in the hippocampus following transient global cerebral ischemia. Present findings indicate that the degree of reduced CB immu- noreactivity might be related with various neuronal damage/death overtime and corresponding areas after ischemic insults.

Analyses of spring mean circulations for major andminor dust storm years in China-Mongolia area

To better understand the dust storm (hereafter DS) inducing circulation in the China-Mongolia (CM) DS activity area,the spring mean circulation features and differences on lower levels in three subregions of the CM DS area for the majorandminor-DS years have,as a whole (not partly),been analyzed,utilizing the National Centers for Environmental Prediction and the National Center for Atmospheric Research (NCEP/NCAR) reanalyzed gridded data,the observed DS frequency data in the CM area,and the composite analysis method.The main conclusions are as follows:(1) Judging from the differences in the DS-inducing systems,dust origins,paths of invading cold air,and main DS-strike areas,the whole CM DS area is roughly divided into the three subre-gions:the East-,Middleand West-CM subregions (in this paper,referred to as E-,M-,and W-CM).(2) In major DSs during spring over the E-CM,the middleand lower-level troughs or cyclones over the Japan Sea and northeastern China (NEC) domi-nate.The invading cold air along the northeastern (NE) or north by east (NE) path often causes the DS in the E-CM region.But nearly the opposite is true inminor DS during spring in E-CM.(3) In the major DS during spring over the M-CM region,the Mongolian troughs or cyclones are the main DS-inducing systems.The strong invading cold air along the northwestern (NW)or north by west (Nw) path causes the DSs in the M-CM region.(4) In the major DSs during spring over the W-CM region,the South Xinjiang heat lows prevail,the intruding cold air has a western path,and creates the DSs in South Xinjiang.(5) In the past 50 years,the DSs over the M-CM region have had the most severe impact on the preceding three subregions of the CM DS area.Overall,DS activities over all of three regions of the CM area decreased in the past (particularly,over Mand W-CM regions since the mid-1980s.But there existed a short and sudden increasing in E-CM in the years 2000-2002.(6) It is circulation changes and desertification evolutions that cause the yearly and decadal changes of DS in CM area,especially the former.With the backdrop of global warming in the future,perhaps the decreased DS activities over Mand W-CM will persist for some time again,and special attention should be paid to ones over E-CM or to the individual DS events over Mand W-CM.

A new subregion mesh method for the investigation of the elastic-plastic impact in flexible multibody systems

Impact processes between flexible bodies often lead to local stress concentration and wave propagation of high frequency. Therefore, the modeling of flexible multibody systems involving impact should consider the local plastic deformation and the strict requirements of the spatial discretization. Owing to the nonlinearity of the stiffness matrix, the reduction of the element number is extremely important. For the contact-impact problem, since different regions have different requirements regarding the element size, a new subregion mesh method is proposed to reduce the number of the unnecessary elements. A dynamic model for flexible multibody systems with elastic-plastic contact impact is established based on a floating frame of reference formulation and complete Lagrange incremental nonlinear finite-element method to investigate the effect of the elastic-plastic deformation as well as spatial discretization. Experiments on the impact between two bodies are carried out to validate the correctness of the elastic-plastic model. The proposed formulation is applied to a slider-crank system with elastic-plastic impact.

Two Efficient Techniques to Simplify the Excitation Setting Problem in R-FDTD Algorithm

As a lately developed technique for FDTD, R FDTD (reduced FDTD) algorithm is complicated for dealing with the problem of excitation setting. In order to get rid of such difficulty, two simple techniques are proposed. One technique is to classify field points into two types according to the value of electric divergence equation. The other technique is subregion connection. The corresponding modified R FDTD can not only inherit the memory efficient character, but also eliminate the complexity aroused by the existence of excitation and conductors. Simulation results are compared between those obtained from traditional FDTD and those from R FDTD. Good agreement is observed.

Exploring the potential to enhance drug distribution in the brain subregion via intranasal delivery of nanoemulsion in combination with borneol as a guider

The number of people with Alzheimer’s disease(AD)is increasing annually,with the nidus mainly concentrated in the cortex and hippocampus.Despite of numerous efforts,effective treatment of AD is still facing great challenges due to the blood brain barrier(BBB)and limited drug distribution in the AD nidus sites.Thus,in this study,using vinpocetine(VIN)as a model drug,the objective is to explore the feasibility of tackling the above bottleneck via intranasal drug delivery in combination with a brain guider,borneol(BOR),using nanoemulsion(NE)as the carrier.First of all,the NE were prepared and characterized.In vivo behavior of the NE after intranasal administration was investigated.Influence of BOR dose,BOR administration route on drug brain targeting behavior was evaluated,and the influence of BOR addition on drug brain subregion distribution was probed.It was demonstrated that all the NE had comparable size and similar retention behavior after intranasal delivery.Compared to intravenous injection,improved brain targeting effect was observed by intranasal route,and drug targeting index(DTI)of the VIN–NE group was 154.1%,with the nose-to-brain direct transport percentage(DTP)35.1%.Especially,remarkably enhanced brain distribution was achieved after BOR addition in the NE,with the extent depending on BOR dose.VIN brain concentration was the highest in the VIN-1-BOR-NE group at BOR dose of 1 mg/kg,with the DTI reaching 596.1%and the DTP increased to 83.1%.BOR could exert better nose to brain delivery when administrated together with the drug via intranasal route.Notably,BOR can remarkably enhance drug distribution in both hippocampus and cortex,the nidus areas of AD.In conclusion,in combination with intranasal delivery and the intrinsic brain guiding effect of BOR,drug distribution not only in the brain but also in the cortex and hippocampus can be enhanced significantly,providing the perquisite for improved therapeutic efficacy of AD.

An assessment of China’s participation in polar subregional organizations

International cooperation is vital for the polar regions.China’s past polar cooperation has tended to focus on intergovernmental and bilateral mechanisms rather than regional cooperation.However,regional and subregional cooperation is playing an increasing role in the polar regions with the rapid development of geopolitics and global climate change.Involvement in three subregional polar organizations—the Asian Forum for Polar Sciences(AFoPS),the Pacific Arctic Group(PAG),and the China-Nordic Arctic Research Center(CNARC)—in the last two decades reflects China’s improved skills and flexibility in participating in international polar cooperation and represents an exercise in the“win-win”principle under China’s Arctic policy.This paper presents a review of the development of polar subregional cooperation,examines China’s participation in three of subregional organizations and provides feasible suggestions for China’s future engagement with these organizations.

Adaptive Noise Detector and Partition Filter for Image Restoration

The random-value impulse noise(RVIN)detection approach in image denoising,which is dependent on manually defined detection thresholds or local window information,does not have strong generalization performance and cannot successfully cope with damaged pictures with high noise levels.The fusion of the K-means clustering approach in the noise detection stage is reviewed in this research,and the internal relationship between the flat region and the detail area of the damaged picture is thoroughly explored to suggest an unique two-stage method for gray image denoising.Based on the concept of pixel clustering and grouping,all pixels in the damaged picture are separated into various groups based on gray distance similarity features,and the best detection threshold of each group is solved to identify the noise.In the noise reduction step,a partition decision filter based on the gray value characteristics of pixels in the flat and detail areas is given.For the noise pixels in flat and detail areas,local consensus index(LCI)weighted filter and edge direction filter are designed respectively to recover the pixels damaged by the RVIN.The experimental results show that the accuracy of the proposed noise detection method is more than 90%,and is superior to most mainstream methods.At the same time,the proposed filtering method not only has good noise reduction and generalization performance for natural images and medical images with medium and high noise but also is superior to other advanced filtering technologies in visual effect and objective quality evaluation.

APPLICATION OF SUBREGION FUNCTION METHOD FOR SOLVING BEAM-BOARD STRUCTURE

In this paper, the solution to the structure consisting of a bead and a board is given as a result of the application of the subregion function method which was suggested in ref. [1]. The same problem is also computed with finite element method. The comparison between the two results shows that the application of the subregion function in the method of weighted residuals is practical and effective, especially for solving compound structures.

Prevalence estimates of Opisthorchis viverrini and Clonorchis sinensis infection in the Greater Mekong subregion:a systematic review and meta-analysis

Background Opisthorchiasis and clonorchiasis,caused by Opisthorchis viverrini and Clonorchis sinensis,respectively,are significant yet neglected foodborne trematodiases in the Great Mekong Subregion(GMS).Despite the reporting of the prevalence of these human liver flukes in the region over the past decades,there has been a lack of a comprehensive and systematic consolidation of this data.Therefore,we aimed to conduct a thorough systematic review and meta-analysis to synthesize and analyze time-trend prevalence estimates of both O.viverrini and C.sinensis across the GMS for the past 30 years.Methods This study undertakes a systematic review using a comprehensive search for published articles in PubMed,EMBASE,Scopus,Cochrane and Thai Journal Online databases until early 2023.The pooled prevalence of O.viverrini and C.sinensis infection was analyzed through a random-effects meta-analysis,with meta-regression analysis used to quantify associations with study characteristics.Sub-group analysis was conducted,whenever comparison data were available,to assess the risk of O.viverrini and C.sinensis infection in each GMS country.Heterogeneity among studies was assessed using the Q statistic and quantified by using the I^(2)Index.Results From a total of 2997 articles,155 articles comprising 218 datasets and 751,108 participants were included for review.The GMS prevalence of O.viverrini was 21.11%[45,083/260,237;95%confidence interval(CI):17.74-24.47%].Pooled prevalence estimates were highly observed in Laos(34.06%,95%CI:26.85-41.26%),followed by Thailand(18.19%,95%CI:13.86-22.51%),and Cambodia(10.48%,95%CI:5.52-15.45%).Myanmar and Vietnam had limited data sources for calculation.Clonorchis sinensis infection in GMS was 25.33%(95%CI:18.32-32.34%),with Guangxi,China,exhibiting the highest prevalence rates at 26.89%(95%CI:18.34-35.43%),while Vietnam had a prevalence rate of 20.30%(95%CI:9.13-31.47%).O.viverrini prevalence decreased significantly over time,whereas C.sinensis infection appeared to be stable consistently over time in both China and Vietnam.Conclusions This comprehensive study,drawing from the largest datasets to date,offers an in-depth systematic prevalence review of human liver flukes in the Greater Mekong Subregion.It underscores the imperative for systematic surveillance,data collection,and the implementation of intervention and control measures for these infectious diseases of poverty.

Changed ACC-DMN functional connectivity after acupuncture with deqi for functional dyspepsia treatment

Objective:To clarify altered whole brain functional connectivity of the anterior cingulate cortex(ACC)in functional dyspepsia(FD)patients,and then to explore cerebral influence of acupuncture with deqi treating for FD.Methods:Thirty-two FD patients and 35 healthy subjects(HS)were firstly scanned by the resting-state blood oxygenation level-dependent functional magnetic resonance imaging(BOLD-fMRI)to compare differences of ACC-based functional connectivity(FC).Then 32 FD patients were randomized to receive 20 sessions’acupuncture treatment with(n=16)and without deqi(n=16),as well as underwent functional magnetic resonance imaging(fMRI)scans after treatment.After group re-division according to deqi response,changes of ACC subregions-based resting-state FC(rsFC)were compared between the actual with and without deqi group.Two seeds with bilateral of each were selected as regions of interest(ROIs)of the ACC,including two from the dorsal ACC:S2(BA24)(x=±5,y=2,z=46,r=3.5 mm)and two from the pregenual ACC:17(BA24)(x=±5,y=38,z=6,r=3.5 mm).The clinical changes of the Nepean Dyspepsia Index(NDI)that measuring symptoms and quality of life(QOL)were also used to further assess the correlation with ACC subregions rsFC in FD patients.Results:Compared to HS,FD patients showed significantly increased ACC subregions rsFC with left fusiform gyrus,temporal cortex,hippocampus(HIPP)/amygdala,temporal pole,and right INS,superior occipital gyrus,and bilateral precuneus,superior parietal lobule(SPL),and decreased rsFC with left postcentral/precentral gyrus(PoG/PrG),supplementary motor area(SMA)and right cerebellum.32 FD patients which were then re-divided into the actual deqi group(n=16)and actual without deqi group(n=16).The decrease of the NDI symptom score(pre-pos)in the actual deqi group was significantly greater than that in the actual without deqi group(P<0.05).Among the two groups,the actual deqi group showed increased ACC subregions rsFC with right SMA and bilateral PrG/PoG,and decreased rsFC with right precuneus,middle occipital gyrus,bilateral posterior cingulate cortex(PCC),HIPP/paraHIPP,angular gyrus and SPL after treatment.In addition,the changed NDI QOL scores(pre-post)of the actual deqi group was significantly positively correlated with their Fisher’s transformed Z value of the altered ACC subregion(left I7)rsFC with right SPL(r=-0.597,P=0.04<0.05,FDR corrected P>0.05).Conclusion:The results tested the hypothesis that the advantage of deqi on efficacy is related to affecting the ACC subregions rsFC.It suggested that deqi might participate in the adaptive modulation of disrupted relationship between the ACC subregions and the default mode network(DMN).

Regional superficial amygdala resting-state functional connectivity in adults infers childhood maltreatment severity

Background:Childhood maltreatment(CM)is a potential risk factor for some neuropsychiatric disorders in adulthood(e.g.depression and anxiety)and alters trajectories of brain development.Accumulating evidence suggests that functional connectivity of the limbic system,especially the amygdala,is highly associated with childhood maltreatment,although not all studies have found this.These inconsistent results may be due to differential alterations of amygdala resting-state functional connectivity(rsFC)following childhood maltreatment.Objective:Our aim was to investigate the relationship between the rsFC of amygdala subregions and CM severity,as well as to develop a stable rsFC-based model for inferring the severity of CM.Methods:In this study,we employed the Childhood Trauma Questionnaire(CTQ)to assess CM severity in each individual.We explored the relationship between the rsFC of amygdala subregions(i.e.centromedial-CMA,basolateral-BLA,superficial-SFA amygdala)and CM experience in a discovery dataset of n=110 healthy Chinese participants by linear multiple regression analysis.Subsequent dimensional and categorical approach were performed to elucidate the relationship between rsFCs and CM severity and CM subtypes,respectively.A support vector regression model was then conducted to validate the associations between rsFCs and total CTQ scores.Moreover,we also verified the model into another independent replication dataset(n=38).Results:Our findings suggested that childhood maltreatment was negatively associated with rsFC between the right superficial amyg-dala and perigenual anterior cingulate cortex(pgACC)/postcentral gyrus(PCG)but not the other two amygdala subregions.Moreover,SFA-pgACC coupling was more associated with physical neglect whereas the SFA-PCG was more related to emotional neglect.In addi-tion,supervised machine learning confirmed that using these two rsFCs as predictors could stably estimate continuous maltreatment severity in both discovery and replication datasets.Conclusion:The current study supports that the rsFCs of superficial amygdala are related to childhood maltreatment and which may be a potential biomarker for the effects of childhood maltreatment-related psychiatric disorders(i.e.depression and anxiety).

Axonal degeneration in the anterior insular cortex is associated with Alzheimer’s co-pathology in Parkinson’s disease and dementia with Lewy bodies

Background:Axons,crucial for impulse transmission and cellular trafficking,are thought to be primary targets of neurodegeneration in Parkinson’s disease(PD)and dementia with Lewy bodies(DLB).Axonal degeneration occurs early,preceeding and exceeding neuronal loss,and contributes to the spread of pathology,yet is poorly described outside the nigrostriatal circuitry.The insula,a cortical brain hub,was recently discovered to be highly vulnerable to pathology and plays a role in cognitive deficits in PD and DLB.The aim of this study was to evaluate morphological features as well as burden of proteinopathy and axonal degeneration in the anterior insular sub-regions in PD,PD with dementia(PDD),and DLB.Methods:α-Synuclein,phosphorylated(p-)tau,and amyloid-βpathology load were evaluated in the anterior insular(agranular and dysgranular)subregions of post-mortem human brains(n=27).Axonal loss was evaluated using modified Bielschowsky silver staining and quantified using stereology.Cytoskeletal damage was comprehensively studied using immunofluorescent multi-labelling and 3D confocal laser-scanning microscopy.Results:Compared to PD and PDD,DLB showed significantly higherα-synuclein and p-tau pathology load,argyrophilic grains,and more severe axonal loss,particularly in the anterior agranular insula.Alternatively,the dysgranular insula showed a significantly higher load of amyloid-βpathology and its axonal density correlated with cognitive performance.p-Tau contributed most to axonal loss in the DLB group,was highest in the anterior agranular insula and significantly correlated with CDR global scores for dementia.Neurofilament and myelin showed degenerative changes including swellings,demyelination,and detachment of the axon-myelin unit.Conclusions:Our results highlight the selective vulnerability of the anterior insular sub-regions to various converging pathologies,leading to impaired axonal integrity in PD,PDD and DLB,disrupting their functional properties and potentially contributing to cognitive,emotional,and autonomic deficits.

Transcriptome landscape of the early Brassica napus seed

Brassica napus L.(canola) is one of the world’s most economically important oilseeds. Despite our growing knowledge of Brassica genetics, we still know little about the genes and gene regulatory networks underlying early seed development. In this work, we use laser microdissection coupled with RNA sequencing to profile gene activity of both the maternal and filial subregions of the globular seed. We find subregions of the chalazal end including the chalazal endosperm, chalazal proliferating tissue, and chalazal seed coat, have unique transcriptome profiles associated with hormone biosynthesis and polysaccharide metabolism. We confirm that the chalazal seed coat is uniquely enriched for sucrose biosynthesis and transport, and that the chalazal endosperm may function as an important regulator of the maternal region through brassinosteroid synthesis. The chalazal proliferating tissue,a poorly understood subregion, was specifically enriched in transcripts associated with megasporogenesis and trehalose biosynthesis, suggesting this ephemeral structure plays an important role in both sporophytic development and carbon nutrient balance, respectively. Finally, compartmentalization of transcription factors and their regulatory circuits has uncovered previously unknown roles for the chalazal pole in early seed development.

Distinct edaphic habitats are occupied by discrete legume assemblages with unique indicator species in the Cape Peninsula of South Africa

Aims the Cape Peninsula is a small area(471 km2)situated on the south-westernmost tip of the Core Cape Subregion(CCR)of South Africa.Within the Cape Peninsula,Fabaceae are the third most species-rich plant family(162 species)and they have the second highest number of endemic species after the Ericaceae.However,legumes are not the dominant taxa in the vegetation.they tend to show patchy distributions within the landscape and different species assemblages usually occupy particular niches at any given locality.the present study undertook to establish if edaphic factors influence legume species distribution in the Cape Peninsula and to determine the key indicator species for the different assemblages.Methods Soils from 27 legume sites,spanning all major geological substrates of the Cape Peninsula,were analysed for 31 chemical and physi-cal properties.Legume species present at each site were recorded and a presence/absence matrix was generated.Cluster analysis and discriminant function analysis(DFA)were run to group the sites based on overall similarity in edaphic characteristics and to identify the soil parameters contributing towards discriminating the groups.Canonical correspondence analysis(CCA)was used to test for a cor-relation between legume species compositions and edaphic factors.the strength of the association between legume species and site groupings based on edaphic properties was assessed using indicator species analysis.Important findings Based on similarity in overall soil characteristics,the sites formed three clusters:one comprising sites of sandstone geology,one with dune sand sites and the third cluster comprising sites of both shale and granite geologies(hereafter referred to as soil types).the DFA confirmed the distinctness of these clusters and the CCA showed a significant correlation between legume species composition and edaphic factors.the key edaphic parameters were clay content,iron(Fe),potassium(K),sulphur(S)and zinc(Zn).these findings reveal that the Cape Peninsula is edaphically heterogeneous and edaphically distinct habitats contain discrete legume species assemblages that can be distinguished by unique indicator species.Furthermore,multiple soil parameters,rather than a single parameter,are involved.therefore,edaphic factors play a significant role in driving the distribution of legume species in the Cape Peninsula and discrete legume species assemblages occupy distinct habitats.