环境有机碳源抑制食弧菌嗜盐噬菌弧菌(Halobacteriovorax vibrionivorans)的捕食生长

【背景】蛭弧菌类群(Bdellovibrio-And-Like Organisms,BALOs)的生长所需碳源主要来源于宿主菌,而环境中各类碳源对其生长的影响还有待探究。【目的】探究不同环境有机碳源对食弧菌嗜盐噬菌弧菌(Halobacteriovorax vibrionivorans)捕食生长的影响,为其后续捕食机制和微生物菌剂的应用研究提供理论基础。【方法】以溶藻弧菌(Vibrio alginolyticus)为宿主,采用96孔板测定细胞吸光度法和双层平板法测定不同糖类化合物、酵母提取物和胰蛋白胨对食弧菌嗜盐噬菌弧菌Y22捕食生长的影响,设置热致死宿主和活宿主、人工海水和Tris-HCl (25 g/L NaCl)培养体系的对比试验,结合菌株基因组信息分析,探索其可能的生长影响机制。【结果】食弧菌嗜盐噬菌弧菌Y22不具备转运外界糖类的相关基因,不能利用环境中的糖类物质作为碳源;宿主溶藻弧菌可以利用蔗糖、麦芽糖、甘露醇生长且产酸,降低人工海水混合培养体系的pH值,从而抑制菌株Y22的捕食;葡萄糖不仅可以改变人工海水混合培养体系的pH值,而且可影响宿主的细胞特性,抑制菌株Y22的捕食识别过程;宿主无法利用淀粉、α-乳糖生长,该类碳源不影响菌株Y22捕食生长。菌株Y22具有蛋白和多肽膜转运蛋白基因,可以通过分解并摄取宿主细胞蛋白质类物质以获取碳源和氮源。外源添加质量浓度为1-5 g/L酵母提取物和胰蛋白胨都会抑制菌株Y22捕食生长,抑制效果随浓度增加而加强,酵母提取物浓度超过4g/L、胰蛋白胨浓度超过5g/L,菌株Y22捕食现象几乎不可见,抑制效果最强。【结论】环境中糖类可通过影响宿主菌代谢产酸或细胞特性,从而影响食弧菌嗜盐噬菌弧菌的捕食生长。食弧菌嗜盐噬菌弧菌可以吸收利用环境中的蛋白或多肽,并因此抑制其捕食生长。该研究结果将为嗜盐噬菌弧菌捕食机制的进一步探究和嗜盐噬菌弧菌微生物菌剂的开发应用提供重要的理论基础。     

蛭弧菌类菌株JU-PX1的生物学特性和16S rDNA序列分析

[目的]研究蛭弧菌类菌株JU-PX1的噬菌特性、形态特征,并分析16S rDNA序列从而对其进行种属鉴定.[方法]采用双层平板法和三角瓶培养法研究蛭弧菌类菌株JU-PX1的噬菌特性,通过光镜和电镜观察其形态,利用16S rDNA序列的蛭弧菌类特异性引物以及细菌通用引物进行PCR扩增.[结果]JU-PX1对10株宿主菌中的6株具有噬菌作用,特别对大肠杆菌和副溶血弧菌侵噬能力较强.菌体呈弧状或杆状,单极鞭毛,大小为(0.2-0.5) μm×(0.8-1.2) μm,在其增殖阶段也有长约3.2 μm的较长个体.扩增后分别获得了一段长为831 bp和1 515 bp的DNA序列,进一步通过NCBI BLAST和MEGA 5.10等软件分析并构建了系统发育树.[结论]蛭弧菌类菌株JU-PX1属于噬菌弧菌属(Bacteriovorax),与海岸噬菌弧菌(Bv.litoralis)亲缘关系最近,两者的16S rDNA序列相似性为93％.     

一株宽谱裂解性溶藻弧菌噬菌体ФV170的分离鉴定及生物学特性

【背景】溶藻弧菌(Vibrio alginolyticus)是水产养殖中重要的条件致病菌,对海水养殖业造成了极大的危害。传统的抗生素疗法引发的耐药问题已经成为全球面临的严峻挑战之一,而作为可替代抗生素的噬菌体疗法已被证实能够有效治疗弧菌病。【目的】深入研究溶藻弧菌噬菌体ФV170的生物学特性,为该菌株在水产动物病害控制中的应用提供数据支持。【方法】以溶藻弧菌V170为宿主菌,采用斑点法从凡纳滨对虾养殖水体中筛选噬菌体,并以双层平板法对噬菌体进行纯化、生长、效价等方面的研究;利用电镜观察噬菌体形态;通过酶切方法分析噬菌体的基因组大小及其类型。【结果】分离得到一株宽谱裂解性噬菌体ФV170,其噬菌斑边缘整齐且通透,12 h直径达1.5 mm。鉴定结果显示,噬菌体ФV170头部为正廿面体的立体对称结构,直径为60 nm-65 nm,尾部长为65 nm-75 nm,宽14 nm-18 nm,核酸类型为dsDNA,基因组大小约为45 kb,对氯仿不敏感,属于有尾噬菌体目(Caudovirales)肌尾噬菌体科(Myoviridae)。此外,噬菌体ФV170可裂解15株溶藻弧菌中的7株,属于种内宽谱;最佳感染复数为0.01;一步生长曲线显示潜伏期为10 min,裂解量为101.3;对65°C以上温度敏感。【结论】分离得到一株宽谱裂解性溶藻弧菌噬菌体,该噬菌体具有治疗海水养殖过程中溶藻弧菌病的潜力。     

湛江海水虾池免培养蛭弧菌类生物的多样性

摘要:【目的】揭示湛江地区海水虾池蛭弧菌类生物(Bdellovibrio-and-like organisms,BALOs)多样性特点,为了解BALOs在虾池生态系统中的作用与合理应用其防治养殖对虾细菌病害提供基础。【方法】从8个热带海水虾池采集水样,提取总DNA,利用BALOs科特异引物对水样总DNA进行扩增,通过构建16S rRNA基因克隆文库与系统发育分析,对虾池水体BALOs多样性和种群结构进行研究。【结果】从嗜盐噬菌弧菌科(Halobacteriovoracaceae)和吞菌弧菌科(Peredibacteraceae)克隆文库中分别获得726个和664个有效克隆子,在16S rRNA基因序列99.5%相似性水平上分别划分为68和44个OTUs(operational taxonomic units)。在16S rRNA基因序列97%相似性上,嗜盐噬菌弧菌可划分为37个种群,且绝大多数属于未培养型,但仅有的5个可培养类群占总文库克隆数量43.5%,其中可培养类群IX 和未培养类群B28分别是最优势和次优势者;吞菌弧菌文库共包含28个种群,未培养类群pa12最为优势,唯一可培养类群A3.12是第2优势者。嗜盐噬菌弧菌与吞菌弧菌多样性大小随盐度高低呈相反趋势,但两者合起来的总BALOs 多样性大小在不同虾池间则比较接近。【结论】湛江地区海水虾池中普遍存在高度多样的嗜盐噬菌弧菌和吞菌弧菌种群,盐度显著影响虾池BALOs种群结构组成。     

两种培养基对对虾苗池海洋蛭弧菌的分离及其多样性分析

【目的】明确海水(Sw)和聚蛋白胨20(Pp20)两种双层琼脂培养基对海洋蛭弧菌的分离计数效果,了解对虾苗池可培养海洋蛭弧菌多样性。【方法】采用双层平板法,比较Sw和Pp20培养基对2株海洋蛭弧菌和对虾苗池未知海洋蛭弧菌的计数效果。通过宿主范围测试和16S rRNA基因序列分析评估两种培养基分离苗池海洋蛭弧菌的多样性。【结果】宿主菌含量高时,Sw培养基对两株已知海洋蛭弧菌的计数值均显著高于(P0.05)Pp20。Sw和Pp20培养基从同一苗池水样分别分离得到21和22株蛭弧菌。根据宿主裂解范围差异,43株分离物可分为15种裂解模式,其中Sw和Pp20培养基各分离到12和8种。16S rRNA基因序列分析表明,所有分离物都被鉴定为噬菌弧菌属(Bacteriovorax)菌株,并可分为6个类群,Sw和Pp20培养基分别分离到6和4个类群。【结论】Sw培养基在分离计数海洋蛭弧菌及其多样性检测上效果均优于Pp20;对虾苗池可培养海洋蛭弧菌具有较高多样性,并以类群XIII、X及一个潜在新类群为优势种群。     

九龙江口沉积物TCBS(Thiosulfate Citrate Bile Salts Sucrose)菌群的分布

【目的】调查九龙江流域对厦门海域潜在的病原菌"污染",为相关侵染性病害的预防和控制提供有价值的资料。【方法】通过TCBS(Thiosulfate Citrate Bile Salts Sucrose)培养基从九龙江河口沉积物中分离到158株细菌,应用16S rRNA基因-RFLP(限制性酶切图谱多样性分析)及16S rRNA基因序列分析等方法对158株细菌进行分子鉴定。【结果】研究结果表明九龙江口沉积物中分布的TCBS菌群分别属于7个属,其中假单胞菌属(Pseudomonas)占28%,气单胞菌属(Aeromonas)占24%,假交替单胞菌属(Pseudoalteromonas)占19%,希瓦氏菌属(Shewanella)占13%,芽孢杆菌属(Bacillus)占11%,弧菌属(Vibrio)占4%,嗜冷杆菌属(Psychrobacter)占1%。不同站位TCBS菌群的组成及各菌群的相对差异明显,其中上游区域以非嗜盐或耐盐细菌为主,下游区域以嗜盐细菌和耐盐细菌为主,具有典型的河口细菌分布特征。盐度对各TCBS菌群的分布具有重要的影响。弧菌在整个河口区所占的比例不大(6%-19%)且集中在下游区域。【结论】九龙江口存在大量的条件致病菌,其中以气单胞菌属为代表的耐盐菌,对厦门海域存在陆源性污染的风险;绝大多数弧菌属于海洋土著细菌,正常情况下(非流行性弧菌病期间)非来源于九龙江冲淡水的直接污染。     

裂解性弧菌噬菌体的分离及生理特性

[目的]弧菌是水产养殖生物中常见的病原菌,本研究旨在寻求水产养殖病害可能的生物防治途径.[方法]本文于2006年春季、2005年秋季从沿岸海水及淡水湖采样,通过"双层平板法"分离裂解性弧菌噬菌体;对噬菌体及宿主进行电镜形态观测,同时采用16S rDNA分子测序技术鉴定宿主,并对噬菌体进行生理特性测定.[结果]从10个样品中分离出96株弧菌、2株裂解性噬菌体(Vibrio/XM/P1、Vibrio/XM/P2),噬菌体宿主分别属于Vibrio alginolyticus(溶澡弧菌)和Vibrio anguillarum(鳗弧菌);噬菌体头部都呈六边形,Vibrio/XM/P2有尾;两株噬菌体活性最适pH分别为7、8,最适温度分别为25℃、30℃,并都对高温和紫外线敏感;Vibrio/XM/P1对乙醚、氯仿不敏感,Vibrio/XM/P2对乙醚、氯仿敏感.     

一株转化琼胶为新琼寡糖菌株的筛选及鉴定

摘要:【目的】筛选一株可以将琼胶转化为新琼寡糖的菌株,并对该菌株进行鉴定。【方法】从紫菜生长区域采集紫菜和该区域海水,用含1‰琼胶的培养基富集培养,逐级稀释涂布、平板划线进行初筛,液体培养进行复筛,DNS法测定琼胶降解产物中还原糖的含量。通过16S rDNA序列分析,结合菌体形态、菌落特征及生理生化特性,确立该菌的系统发育学地位。【结果】从紫菜振荡液中筛选出一株可以产琼胶酶的菌株HJPHYXJ-1,该菌属于革兰氏阴性菌,16S rDNA序列同源性与需钠弧菌(Vibrio natriegens)的达到了99%,结合形态特征和生理生化实验结果鉴定该菌为需钠弧菌。HPLC法测定酶解产物为新琼寡糖。【结论】HJPHYXJ-1被筛选用于转化琼胶,酶解产物的聚合度在2－12 之间,是以二糖为单位的新琼寡糖,该菌产生的酶为β-琼胶酶。     

高温海藻床中微生物的分离鉴定及其耐热、耐盐特性研究

【目的】对印度洋卡利安达岛海洋热泉周边的高温海藻床中的微生物进行分离培养和16S rDNA种属鉴定,并研究其耐热和耐盐特性。【方法】采集海藻床中马尾藻、沉积物和海水样品,采用MGYTC培养基,分别于55°C和30°C对样品中的微生物进行培养和分离纯化;采用16S rDNA鉴定种属并构建进化树;研究培养温度和盐度对几种菌株生长的影响。【结果】共获得4个纲、9个属的12种菌株,与已知种属的相似度高于98%。芽孢杆菌纲嗜热放线菌科2个属的菌株和芽孢杆菌属菌株在55°C培养时获得,为嗜热菌株;其中高温放线糖莱斯菌(Laceyella sacchari)和热噬淀粉芽孢杆菌(Bacillus thermoamylovorans)可以在0 90的盐度范围生长。γ-变形菌纲希瓦氏属的Shewanella upenei、Shewanella algidipiscicola和鲍希瓦氏菌(Shewanella haliotis)可适应30°C 55°C的生长环境。【结论】研究获得的菌株,具有耐热、耐盐或对温度适应范围广等特性,有望成为生物技术领域的新资源;分离获得的Tepidibacter formicigenes,深海微小杆菌(Exiguobacterium profundum)和魔鬼弧菌(Vibrio diabolicus)曾被报道来源于深海热液区,这对于阐明海洋热泉与深海热液环境的内在联系提供了参考。     

四个类群海洋蛭弧菌类生物生长特性的比较

研究了噬菌弧菌科(Bacteriovoracaceae) 4个类群共12株海洋蛭弧菌类生物(Bdellovibrio- and-like organisms, BALOs)的生长温度和盐度范围及其对6种常见对虾病原弧菌的裂解能力, 并通过透射电镜分析了其中4个代表菌株的形态特征。结果表明, 同一群或亚群内菌株的生长温度或盐度相同, 即类群IV、VI、IX、X菌株的生长温度范围分别为20°C~35°C、15°C~35°C、15°C~ 40°C和10°C~40°C, 最适生长温度为30°C或35°C; 生长盐度范围分别为5‰~40‰、2.5‰~30‰、5‰~60‰和5‰~60‰, 最适生长盐度分别为10‰、5‰、20‰和20‰。测试的6种弧菌中有3种可被全部BALOs裂解, 而其它弧菌仅被部分BALOs裂解, 但即使同一类群菌株, 对某些弧菌也表现不同的裂解能力。形态上, 4株不同类群BALOs均呈典型的弧状细胞, 具极生单鞭毛。     

Foreign exploration for Scirtothrips perseae Nakahara (Thysanoptera: Thripidae) and associated natural enemies on avocado (Persea americana Miller)

Scirtothrips perseae Nakahara was discovered attacking avocados in California, USA, in 1996. Host plant surveys in California indicated that S. perseae has a highly restricted host range with larvae being found only on avocados, while adults were collected from 11 different plant species. As part of a management program for this pest, a “classical” biological control program was initiated and foreign exploration was conducted to delineate the home range of S. perseae, to survey for associated natural enemies and inventory other species of phytophagous thrips on avocados grown in Mexico, Guatemala, Costa Rica, the Dominican Republic, Trinidad, and Brazil. Foreign exploration efforts indicate that S. perseae occurs on avocados grown at high altitudes (>1500 m) from Uruapan in Mexico south to areas around Guatemala City in Guatemala. In Costa Rica, S. perseae is replaced by an undescribed congener as the dominant phytophagous thrips on avocados grown at high altitudes (>1300 m). No species of Scirtothrips were found on avocados in the Dominican Republic, Trinidad, or Brazil. In total, 2136 phytophagous thrips were collected and identified, representing over 47 identified species from at least 19 genera. The significance of these species records is discussed. Of collected material 4% were potential thrips biological control agents. Natural enemies were dominated by six genera of predatory thrips (Aeolothrips, Aleurodothrips, Franklinothrips, Leptothrips, Scolothrips, and Karnyothrips). One genus each of parasitoid (Ceranisus) and predatory mite (Balaustium) were found. Based on the results of our sampling techniques, prospects for the importation of thrips natural enemies for use in a “classical” biological control program in California against S. perseae are not promising.     

Structural Peculiarities of Na+,K+-ATPase Isozymes from the Calf Brain

Functionally active preparations of Na⁺,K⁺-ATPase isozymes from calf brain that contain catalytic subunits of three types (1, 2, and 3) were obtained using two approaches: a selective removal of contaminating proteins by the Jorgensen method and a selective solubilization of the enzyme with subsequent reconstitution of their membrane structure by the Esmann method. The ouabain inhibition constants were determined for the isozymes. The real isozyme composition of the Na⁺ pump from the grey matter containing glial cells and the brain stem containing neurons was determined. The plasma membranes of glial cells were shown to contain mainly Na⁺,K⁺-ATPase of the 11 type and minor amounts of isozymes of the 22(1) and the 31(2) type. The axolemma contains 21 and 31 isozymes. A carbohydrate analysis indicated that 11 enzyme preparations from the brain grey matter substantially differ from the renal enzymes of the same composition in the glycosylation of the 1 isoform. An enhanced sensitivity of the 3 catalytic subunit of Na⁺,K⁺-ATPase from neurons to endogenous proteolysis was found. A point of specific proteolysis in the amino acid sequence PNDNR⁴⁹² Y⁴⁹³ was localized (residue numbering is that of the human 3 subunit). This sequence corresponds to one of the regions of the greatest variability in 1-, 2-, 3-, and 4-subunits, but at the same time, it is characteristic of the 3 isoforms of various species. The presence of the 3 isoform of tubulin (cytoskeletal protein) was found for the first time in the high-molecular-mass Na⁺,K⁺-ATPase 31 isozyme complex isolated from the axolemma of brain stem neurons, and its binding to the 3 catalytic subunit was shown.     

1H and13C-NMR analysis of four pentasaccharides from urine of blood-group A and B,Leb adults. Confirmation of the structure of two new oligosaccharides: Fuc(α1–2)[GalNAc(α1–3)]Gal(β1–3)[Fuc(α1–4)]Glc and Fuc(α1–2)[Gal(α1–3)]Gal(β1–3)[Fuc(α1–4)]Glc

The major pentasaccharides Fuc(1-2)[GalNAc(1-3)]Gal(1-4)[Fuc(1-3)]Glc and Fuc(1-2) [Gal(1-3)]Gal(1-4)[Fuc(1-3)]Glc, which are normally present in the urine of bloodgroup A Le^b and B Le^b healthy subjects, were each found to be contaminated by a minor component when analysed by¹H-NMR. The determination of these structures, Fuc(1-2) [GalNAc(1-3)]Gal(1-3)[Fuc(1-4)]Glc and Fuc(1-2) [Gal(1-3)]Gal(1-3)[Fuc(1-4)]Glc, was based on the results of methylation analysis and¹H/¹³C-NMR spectroscopy.Abbreviations HPLC high performance liquid chromatography - GLC gas liquid chromatography - NMR nuclear magnetic resonance - COSY correlation spectroscopy - Gal d-galactopyranose - GalNAc 2-acetamido-2-deoxy-d-galactopyranose - Glc d-glucopyranose - Fuc l-fucopyranose - LNDFH I lacto-N-difucohexaose I (Le^b determinant     

Characterization of SSEA-1 glycolipids from the brain of a patient with fucosidosis

Neutral glycolipids from the brain of a patient with Fucosidosis were analyzed and two complex glycolipids containing five and eight sugars were isolated from the cortical grey matter. These two glycolipids reacted with antibodies recognizing the SSEA-1 [Le^x(X)] carbohydrate determinant. SSEA-1 glycolipids are normally expressed in human embryonic brain but are found in only small amounts in postnatal human brain. The accumulation of the two SSEA-1 glycolipids in Fucosidosis brain thus represents a defect which affects the normal developmentally regulated decrease in postnatal, expression of these glycolipids, and may be a contributing factor in the abnormal brain development associated with the disease. Chemical characterization of the two isolated glycolipids by gas chromatographic and mass spectrometric analyses has identified the two glycolipids as lacto-N-fucopentaosylceramide (III) and difucosyl-neolactonorhexaosylceramide.Abbreviations DCl direct chemical ionization - FAB tastatiom bombardment - GC gas chromatography - GSLs glycosphingolipids - MS mass spectrometry - SSEA-1 stage specific embryonic antigen-1 - TLC thin layer chromatographys     

The evolution of the Hox cluster: insights from outgroups

Two burgeoning research trends are helping to reconstruct the evolution of the Hox cluster with greater detail and clarity. First, Hox genes are being studied in a broader phylogenetic sampling of taxa: the past year has witnessed important new data from teleost fishes, onychophorans, myriapods, polychaetes, glossiphoniid leeches, ribbon worms, and sea anemones. Second, commonly accepted notions of animal relationships are being challenged by alternative phylogenetic hypotheses that are causing us to rethink the evolutionary relationships of important metazoan lineages, especially arthropods, annelids, nematodes, and platyhelminthes.     

N-andO-glycosylation of glycoprotein C synthesized by Herpes simplex virus type 1-infected ricin resistant cells

The progeny of Herpes simplex virus type 1 (HSV-1) grown in ricin-resistant 14 cells (Ric^R14) lackingN-acetylglucosaminyltransferase I was released in the extracellular medium at a very low rate. By using a monoclonal antibody immobilized on Sepharose we purified from HSV-1-infected Ric^R14 cells a viral glycoprotein (gC), which carries bothN-andO-linked oligosaccharides. Glycopeptides obtained from [³H]mannoselabeled gC by Pronase digestion were entirely susceptible to endo--N-acetylglucosaminidase H, and the major oligosaccharide released was Man₄GlcNAc. The accumulation of this high-mannose species was related to the enzymic defect of the host cells and to the long retention of the viral glycoprotein within the cells. The extent ofO-glycosylation evaluated in [¹⁴C]glucosamine-labeled gC from Ric^R14 cells as compared to that of gC from wild type cells did not appear to be significantly modified.Abbreviations Con A concanavalin A - BHK cells baby hamster kidney cells - HSV Herpes simplex virus     

Elucidation of Structure of Lipid A from the Marine Gram-Negative Bacterium Pseudoalteromonas haloplanktis ATCC 14393T

The chemical structure of lipid A, from the marine -proteobacterium Pseudoalteromonas haloplanktis 14393, a main product of lipopolysaccharide hydrolysis (1% AcOH), was determined using chemical methods and NMR spectroscopy. The lipid A was shown to be -1,6-glucosaminobiose 1,4-diphosphate acylated with two (R)-3-hydroxyalkanoic acid residues at C3 and C3 and amidated with one (R)-3-hydroxydodecanoyl and one (R)-3-dodecanoyloxydodecanoyl residue at N2 and N2, respectively.     

Phylogeny of cardinalfishes (Teleostei: Gobiiformes: Apogonidae) and the evolution of visceral bioluminescence

The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.     

Molecular phylogeny of Phebalium (Rutaceae: Boronieae) and related genera based on the nrDNA regions ITS 1+2

Parsimony analyses of the internal transcribed spacer regions of nuclear ribosomal DNA (ITS 1 & ITS 2) for 38 taxa sampled from the Phebalium group (Rutaceae: Boronieae) and two outgroups confirm that, with the exception of Phebalium sensu stricto and Rhadinothamnus, six of the currently recognised genera within the group are monophyletic. The data indicate that Phebaliums. str. is paraphyletic with respect to Microcybe, and Rhadinothamnus is paraphyletic with respect to Chorilaena. Rhadinothamnus and Chorilaena together are the sister group to Nematolepis. Drummondita, included as an outgroup taxon, clustered within the ingroup as sister to Muiriantha and related to Asterolasia.The phylogeny suggests that the evolution of major clades within a number of these genera (e.g. Phebalium) relates to vicariance events between eastern and south-western Australia. Leionema is an eastern genus, with the most basal taxon being the morphologically distinct Leionema ellipticum from northern Queensland. Leionema also includes one species from New Zealand, but this species (as with some others) proved difficult to sequence and its phylogenetic position remains unknown. Taxonomic changes at the generic level are recommended.The authors wish to thank Paul G.Wilson, PERTH, for advice and discussion, and Paul Forster, BRI, for collecting and providing material of Leionema ellipticum. The project was supported by a Melbourne University Postgraduate Award (to BM), the Australian Biological Resources Study (ABRS), Australian Systematic Botany Society and Wolf Den (Australia) Investments.