The two‐component histidine kinase Fhk1 controls stress adaptation and virulence of Fusarium oxysporum

Fungal histidine kinases (HKs) have been implicated in different processes, such as the osmostress response, hyphal development, sensitivity to fungicides and virulence. Members of HK class III are known to signal through the HOG mitogen‐activated protein kinase (MAPK), but possible interactions with other MAPKs have not been explored. In this study, we have characterized fhk1, encoding a putative class III HK from the soil‐borne vascular wilt pathogen Fusarium oxysporum. Inactivation of fhk1 resulted in resistance to phenylpyrrole and dicarboximide fungicides, as well as increased sensitivity to hyperosmotic stress and menadione‐induced oxidative stress. The osmosensitivity of Δfhk1 mutants was associated with a striking and previously unreported change in colony morphology. The Δfhk1 strains showed a significant decrease in virulence on tomato plants. Epistatic analysis between Fhk1 and the Fmk1 MAPK cascade indicated that Fhk1 does not function upstream of Fmk1, but that the two pathways may interact to control the response to menadione‐induced oxidative stress.     

脱氧鬼臼毒素对美洲大蠊的毒力及几种酶系的影响

采用药膜法测试了脱氧鬼臼毒素对美洲大蠊Periplaneta americana初孵若虫的触杀活性,并测定了其对成虫中枢神经系统乙酰胆碱酯酶（AChE）和腺苷三磷酸酶(ATPase)离体活性的影响。结果表明：脱氧鬼臼毒素对美洲大蠊初孵若虫具有较强的毒杀活性,在接触时间24、48、72和96 h 的LC₅₀分别为26.26、4.68、1.51和0.62 μg/cm²;其对AChE没有明显影响; 对Na⁺ -K⁺ -ATPase有明显抑制作用,并存在浓度 效应关系,IC₅₀为44.9 μmol/L; 对Ca²⁺-Mg²⁺-ATPase表现出低剂量激活,高剂量抑制的现象。结果提示美洲大蠊的AChE不是脱氧鬼臼毒素靶标,而ATPase可能是脱氧鬼臼毒素的重要靶标之一。     

Chirocentrids as engrauloids: evidence from suspensorium,branchial arches,and infraorbital bones (Clupeomorpha,Teleostei)

The Chirocentridae is a family of highly specialized large predatory clupeomorphs composed of two species from coastal waters of the Indian and western Pacific Oceans. Peculiarities of the anatomy of these fishes have puzzled ichthyologists who attempted to resolve their phylogenetic relationships. Despite controversy, it is currently accepted that the Chirocentridae is a family of Clupeiformes, included with the Clupeidae in the superfamily Clupeoidea. New data support an alternative hypothesis. Seven previously unreported derived character states from the suspensorium, branchial arches, and infraorbitals strongly indicate a hitherto unsuspected sister group relationship between the Chirocentridae and Engrauloidea, which comprises approximately 140 species of the commercially important fishes known as anchovies. These are character states: (1) the anterior margin of metapterygoid located anterior to the quadrate; (2) the ventral limb of hyomandibula and quadrate not separated by the metapterygoid; (3) the posterodorsal margin of metapterygoid in line with the condyle of articulation of the hyomandibula with the opercle; (4) the presence of a laminar outgrowth of the anterior margin of the quadrate; (5) the endochondral portion of the quadrate in the shape of an isosceles triangle; (6) the presence and arrangement of autogenous tooth plates on ceratobranchials 1 to 3; and (7) posterior region of infraorbital 1 well developed and extending along the ventral margin of infraorbital 2. Three of those character states are further modified and hypothesized as synapomorphies of the Engrauloidea: (1′) a substantial portion of the metapterygoid situated anterodorsal to the quadrate, (2′) articulation between the ventral limb of the hyomandibula and the quadrate, and (7′) infraorbitals 1 and 3 articulating by means of a well‐developed laminar process of the posterior region of infraorbital 1. The separation of the dorsal, paired elements of the branchial arches of the Chirocentridae and representative Engrauloidea is apomorphic within the Clupeoidei, and constitutes circumstantial evidence for the sister group relationship between those clades. Microphagy within the Engrauloidea is secondary, homoplastic to the same condition present in other clades of the Clupeiformes. The decomposition of character complexes into discrete morphological characters and its use in phylogenetic inference is discussed. The sister group relationship between the Chirocentridae and Engrauloidea renders the Clupeoidea paraphyletic. A new classification of the Clupeoidei, with the inclusion of the Chirocentridae in the Engrauloidea, is proposed. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 156 , 363–383.