Scd1 ab-Xyk : a new asebia allele characterized by a CCC trinucleotide insertion in exon 5 of the stearoyl-CoA desaturase 1 gene in mouse

We describe here a spontaneous, autosomal recessive mutant mouse suffering from skin and hair defects, which arose in the outbred Kunming strain. By haplotype analysis and direct sequencing of PCR products, we show that this mutation is a new allele of the asebia locus with a naturally occurring mutation in the Scd1 gene (a CCC insertion at nucleotide position 835 in exon 5), which codes for stearoyl-CoA desaturase 1. This mutation introduces an extra proline residue at position 279 in the Scd1 protein. The mutant mice, originally designated km/km but now assigned the name Scd1 ^ab-Xyk (hereafter abbreviated as ab ^Xyk / ab ^Xyk ), have a similar gross and histological phenotype to that reported for previously characterized allelic asebia mutations ( Scd1 ^ab , Scd1 ^abJ , Scd1 ^ab2J , and Scd1 ^tm1Ntam ). Histological analysis showed they were also characterized by hypoplasic sebaceous glands and abnormal hair follicles. In a cross between Kunming- ab ^Xyk / ab ^Xyk and ABJ/Le- ab ^J / ab ^J mice, all the progeny showed the same phenotype, indicating that the two mutations were non-complementing and therefore allelic. Comparisons with the other four allelic mutants indicate that the Scd1 ^ab-Xyk mutation causes the mildest change in Scd1 function. This new mouse mutant is a good model not only for the study of scarring alopecias in humans, which are characterized by hypoplasic sebaceous glands, but also for studying the structure and function of the Scd1 protein.Communicated by G. ReuterThe first two authors contribute equally to this work     

Mapping of susceptibility to Marek's disease within the major histocompatibility (B) complex by refined typing of White Leghorn chickens

The major histocompatibility (B) complex of a distinct commercial pure White Leghorn chicken line was characterized using serological, biochemical and restriction fragment length polymorphism (RFLP) typing. Line B chickens displayed a high recombination frequency within the B complex. Three recombinant haplo-types were identified. The influence of these haplotypes was determined in relation to the haplotypes B^l9 and B²¹ on their resistance to Marek's disease (MD) in an experimental infection with the virus. Offspring of sires with a recombinant haplotype in combination with B¹⁹ or B²¹, and dams, which were homozygous B¹⁹/B¹⁹ or B²¹/B²¹ were infected. The B type of the offspring had a significant effect upon survival. Animals with B complex types B²¹/B²¹, B¹³⁴/B²¹ and B²³⁴/B²¹ were relatively resistant to MD (24–32% mortality), whereas B¹⁹/B¹⁹ birds were highly susceptible (68% mortality). Animals with a recombinant halpotype B^19r21 (B-G²¹, B-F¹⁹) were equally susceptible to MD as birds with the complete B¹⁹ haplotype. In contrast to earlier publications, resistance was not inherited as a dominant trait. Apparently, B¹⁹ was associated with a dominant susceptibility. The gene(s) associated with the B complex and involved in resistance to MD were localized within the B-F/B-L region. However, the association with a presumably non-coding subregion of B-G could not be excluded.     

Phylogeny and classification of Aedini (Diptera: Culicidae), based on morphological characters of all life stages

Higher‐level relationships within Aedini, the largest tribe of Culicidae, are explored using morphological characters of eggs, fourth‐instar larvae, pupae, and adult females and males. In total, 172 characters were examined for 119 exemplar species representing the existing 12 genera and 56 subgenera recognized within the tribe. The data for immature and adult stages were analysed separately and in combination using equal (EW) and implied weighting (IW). Since the classification of Aedini is based mainly on adult morphology, we first tested whether adult data alone would support the existing classification. Overall, the results of these analyses did not reflect the generic classification of the tribe. The tribe as a whole was portrayed as a polyphyletic assemblage of Aedes and Ochlerotatus within which eight (EW) or seven (IW) other genera were embedded. Strict consensus trees (SCTs) derived from analyses of the immature stages data were almost completely unresolved. Combining the adult and immature stages data resulted in fewer most parsimonious cladograms (MPCs) and a more resolved SCT than was found when either of the two data subsets was analysed separately. However, the recovered relationships were still unsatisfactory. Except for the additional recovery of Armigeres as a monophyletic genus, the groups recovered in the EW analysis of the combined data were those found in the EW analysis of adult data. The IW analysis of the total data yielded eight MPCs consisting of three sets of two mutually exclusive topologies that occurred in all possible combinations. We carefully studied the different hypotheses of character transformation responsible for each of the alternative patterns of relationship but were unable to select one of the eight MPCs as a preferred cladogram. Overall, the relationships within the SCT of the eight MPCs were a significant improvement over those found by equal weighting. Aedini and all existing genera except Ochlerotatus and Aedes were recovered as monophyletic. Ochlerotatus formed a polyphyletic assemblage basal to Aedes. This group included Haemagogus and Psorophora, and also Opifex in a sister‐group relationship with Oc. (Not.) chathamicus. Aedes was polyphyletic relative to seven other genera, Armigeres, Ayurakitia, Eretmapodites, Heizmannia, Udaya, Verrallina and Zeugnomyia. With the exception of Ae. (Aedimorphus), Oc. (Finlaya), Oc. (Ochlerotatus) and Oc. (Protomacleaya), all subgenera with two or more species included in the analysis were recovered as monophyletic. Rather than leave the generic classification of Aedini in its current chaotic state, we decided a reasonable and conservative compromise classification would be to recognize as genera those groups that are ‘weighting independent’, i.e. those that are common to the results of both the EW and IW analyses of the total data. The SCT of these combined analyses resulted in a topology of 29 clades, each comprising between two and nine taxa, and 30 taxa (including Mansonia) in an unresolved basal polytomy. In addition to ten genera (Armigeres, Ayurakitia, Eretmapodites, Haemagogus, Heizmannia, Opifex, Psorophora, Udaya, Verrallina and Zeugnomyia), generic status is proposed for the following: (i) 32 existing subgenera of Aedes and Ochlerotatus, including nine monobasic subgenera within the basal polytomy, i.e. Ae. (Belkinius), Ae. (Fredwardsius), Ae. (Indusius), Ae. (Isoaedes), Ae. (Leptosomatomyia), Oc. (Abraedes), Oc. (Aztecaedes), Oc. (Gymnometopa) and Oc. (Kompia); (ii) three small subgenera within the basal polytomy that are undoubtedly monophyletic, i.e. Ae. (Huaedes), Ae. (Skusea) and Oc. (Levua), and (iii) another 20 subgenera that fall within the resolved part of the SCT, i.e. Ae. (Aedes), Ae. (Alanstonea), Ae. (Albuginosus), Ae. (Bothaella), Ae. (Christophersiomyia), Ae. (Diceromyia), Ae. (Edwardsaedes), Ae. (Lorrainea), Ae. (Neomelaniconion), Ae. (Paraedes), Ae. (Pseudarmigeres), Ae. (Scutomyia), Ae. (Stegomyia), Oc. (Geoskusea), Oc. (Halaedes), Oc. (Howardina), Oc. (Kenknightia), Oc. (Mucidus), Oc. (Rhinoskusea) and Oc. (Zavortinkius). A clade consisting of Oc. (Fin.) kochi, Oc. (Fin.) poicilius and relatives is raised to generic rank as Finlaya, and Downsiomyia Vargas is reinstated from synonymy with Finlaya as the generic name for the clade comprising Oc. (Fin.) leonis, Oc. (Fin.) niveus and their relatives. Three other species of Finlaya?Oc. (Fin.) chrysolineatus, Oc. (Fin.) geniculatus and Oc. (Fin.) macfarlanei? fall within the basal polytomy and are treated as Oc. (Finlaya) incertae sedis. Ochlerotatus (Ochlerotatus) is divided into three lineages, two of which, Oc. (Och.) atropalpus and Oc. (Och.) muelleri, are part of the basal polytomy. The remaining seven taxa of Oc. (Ochlerotatus) analysed, including the type species, form a reasonably well‐supported group that is regarded as Ochlerotatus s.s. Ochlerotatus (Rusticoidus) is retained as a subgenus within Ochlerotatus s.s. Ochlerotatus (Nothoskusea) is recognized as a subgenus of Opifex based on two unique features that support their sister‐group relationship. A new genus, Tanakaius gen. nov. , is proposed for Oc. (Fin.) togoi and the related species Oc. (Fin.) savoryi. The taxonomic status and generic placement of all currently valid species of Aedini are listed in an appendix. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 142 , 289?368.     

Three members of the S multigene family are linked to the S locus of Brassica

Two self-incompatibility genes in Brassica, SLG and SRK (SLG encodes a glycoprotein; SRK encodes a receptor-like kinase), are included in the S multigene family. Products of members of the S multigene family have an SLG-like domain (S domain) in common, which may function as a receptor. In this study, three clustered members of the S multigene family, BcRK1, BcRL1 and BcSL1, were characterized. BcRK1 is a putative functional receptor kinase gene expressed in leaves, flower buds and stigmas, while BcRL1 and BcSL1 are considered to be pseudogenes because deletions causing frameshifts were identified in these sequences. Sequence and expression pattern of BcRK1 were most similar to those of the Arabidopsis receptor-like kinase gene ARK1, indicating that BcRK1 might have a function similar to that of ARK1, in processes such as cell expansion or plant growth. Interestingly, the region containing BcRK1, BcRL1 and BcSL1 is genetically linked to the S locus and the physical distance between SLG, SRK and the three S-related genes was estimated to be less than 610 kb. Thus the genes associated with self-incompatibility exist within a cluster of S-like genes in the genome of Brassica. Received: 15 April 1997 / Accepted: 13 June 1997     

Food attraction and population growth of fungivorous nematodes with different fungi

Food attraction of the fungivorous nematodes Aphelenchus avenae and Aphelenchoides spp. to seven fungal species (Pyrenochaeta lycopersici, Botrytis cinerea, Rhizoctonia solani strains AG 3 and AG 2‐1, Verticillium dahliae, Pochonia bulbillosa, Mortierella hyalina and Trichoderma harzianum) was determined on agar plates by counting the number of test nematodes present on the mycelium of each fungus 24 h after inoculation. Population growth of A. avenae and Aphelenchoides spp. on five of the seven fungi included in the attraction test (P. lycopersici, R. solani strain AG 3, V. dahliae, P. bulbillosa and T. harzianum) was also determined on agar plates by counting nematode numbers every week during a 6‐week period. A. avenae and Aphelenchoides spp. were attracted to all the fungi tested. A. avenae was preferentially attracted to V. dahliae (P < 0.0001), and Aphelenchoides spp. did not show any preference except for low attraction to R. solani. A. avenae and Aphelenchoides spp. reproduced on all fungal species tested. After 6 weeks of incubation, the highest number of nematodes was found on P. lycopersici and P. bulbillosa, while the lowest number occurred on R. solani for A. avenae and on T. harzianum for Aphelenchoides spp. The suitability of a fungus as a host was not clearly related to the attraction to that fungus.     

Molecular structure of rare but geographically widespread sn-glycerol-3-phosphate dehydrogenase ‘ultra-fast’ electrophoretic alleles in Drosophila melanogaster

Six naturally occurring but rare alleles of sn-glycerol-3-phosphate dehydrogenase (Gpdh) in Drosophila melanogaster have been investigated in this study. They all belong to a class of Gpdh ^UF (ultra-fast) alleles, because their electrophoretic mobilities are faster than that of the Gpdh ^F (fast) allele. The Gpdh ^UF variants are widespread, and have been reported from five continents. DNA sequence analysis has shown that the change in electrophoretic mobility was in each allele caused by a single amino acid residue substitution in the encoded protein. In the Xiamen ^UF allele it is a substitution of lysine (AAA) to asparagine (AAT) in exon 1 (residue 3). An asparagine (AAT) to aspartate (GAT) change was found in exon 6 (residue 336) in the Iowa ^UF and Netherlands ^UF alleles. The mobility of the Raleigh ^UF allele was altered by a valine (GTG) to glutamate (GAG) substitution in exon 3 (residue 76). Two mutations were detected in the Brazzaville ^UF allele: a lysine (AAG) to methionine (ATG) substitution in exon 2 (residue 68) is responsible for the ultra-fast phenotype of this variant, while a tyrosine (TAT) to phenylalanine (TTT) substitution in exon 4 (residue 244) is not expected to alter the electrophoretic mobility of the encoded protein. These results indicate that the Gpdh ^UF alleles originate from different mutational events, and only two of them — Iowa ^UF and Netherlands ^UF — might share a common ancestry. The GPDH activity of the Iowa ^UF allele is intermediate between those of the Gpdh ^S and Gpdh ^F control stocks. The other Gpdh ^UF variants have lower activities than the controls: Xiamen ^UF -83%, Raleigh ^UF -80% and Brazzaville ^UF -73% of the Gpdh ^F control.     

Self-compatible peach (<Emphasis Type="Italic">Prunus persica</Emphasis>) has mutant versions of the <Emphasis Type="Italic">S</Emphasis> haplotypes found in self-incompatible <Emphasis Type="Italic">Prunus</Emphasis> species

This study demonstrates that self-compatible (SC) peach has mutant versions of S haplotypes that are present in self-incompatible (SI) Prunus species. All three peach S haplotypes, S ¹ , S ² , and S ^2m , found in this study encode mutated pollen determinants, SFB, while only S ^2m has a mutation that affects the function of the pistil determinant S-RNase. A cysteine residue in the C5 domain of the S ^2m -RNase is substituted by a tyrosine residue, thereby reducing RNase stability. The peach SFB mutations are similar to the SFB mutations found in SC haplotypes of sweet cherry (P. avium) and Japanese apricot (P. mume). SFB ¹ of the S ¹ haplotype, a mutant version of almond (P. dulcis) S ^k haplotype, encodes truncated SFB due to a 155 bp insertion. SFB ² of the S ² and S ^2m haplotypes, both of which are mutant versions of the S ^a haplotype in Japanese plum (P. salicina), encodes a truncated SFB due to a 5 bp insertion. Thus, regardless of the functionality of the pistil determinant, all three peach S haplotypes are SC haplotypes. Our finding that peach has mutant versions of S haplotypes that function in almond and Japanese plum, which are phylogenetically close and remote species, respectively, to peach in the subfamily Prunoideae of the Roasaceae, provides insight into the SC/SI evolution in Prunus. We discuss the significance of SC pollen part mutation in peach with special reference to possible differences in the SI mechanisms between Prunus and Solanaceae.     

The paracellular channel for water secretion in the upper segment of the Malpighian Tubule of Rhodnius prolixus

Lumen to bath J ₁₂/C ₁ and bath to lumen J ₂₁/ C ₂ fluxes per unit concentration of 19 probes with diameters (d ^m) ranging from 3.0–30.0 Å (water, urea, erythritol, mannitol, sucrose, raffinose and 13 dextrans with d ^m 9.1–30.0 Å) were measured during volume secretion (J _v ) in the upper segment of the Malpighian Tubule of Rhodnius by perfusing lumen and bath with ¹⁴C or ³H-labeled probes. J _net=(J ₁₂/C ₁ – J ₂₁/C ₂) was studied as a function of J _v · J _v was varied by using different concentrations of 5-hydroxy tryptamine. J _net for ³H-water was not different from J _v We found: (i) A strong correlation between J _net and J _v for 8 probes d ^m =3.0–11.8 Å (group a probes), indicating that the convective component of J _net is more important than its diffusive component and than unstirred layers effects which are negligible. Therefore group a probes are solvent dragged as they cross the epithelium, (ii) There is no correlation between J _net and J _v for 11 probes with d ^m=11.8–30 Å (group b). Therefore these probes must cross the epithelium by diffusion and not by solvent drag, (iii) In a plot of J _net/J _v vs. d ^m group a probes show a steep linear relation with a slope = –0.111, while for group b probes the slope is –0.002. Thus there is a break between groups a and b in this plot. We tried to fit the data with models for restricted diffusion and convention through cylindrical or parallel slit pathways. We conclude that (i) group a probes are dragged by water through an 11.0 Å-wide slit, (ii) Most of J _v must follow an extracellular noncytosolic pathway, (iii) Group b probes must diffuse through a 42 Å-wide slit, (iv) A cylindrical pathway does not fit the data.E.G. is a Visiting Scientist at IVIC. It is a pleasure to thank Drs. A.E. Hill and Bruria Shachar-Hill for their suggestion of the use of dextrans, their instruction and help with the dextran separation technique, and their extensive discussions. Dr. R. Apitz, Mr H. Rojas and Mrs. Fulvia Bartoli were most helpful with suggestions during the course of the experimental work. Mr. Jose Mora was fundamental help with the equipment. Mrs. Lelis Ochoa and Mr. Luis F. Alvarez helped with some of the drawings. This work was partially supported by CONICIT, Fundación Polar and CDCH of UCV. It is a pleasure to thank Dr. H. Passow and Dr. K.J. Ullrich at the Max Planck Institut für Biophysik (Frankfurt/Main) where this work was initiated.     

Direct Calculation of a Tree Length Using a Distance Matrix

Comparative studies of tree-building methods have shown minimum evolution to be in general an accurate criterion for selecting a true tree. To improve the use of this criterion, this paper proposes a method for rapidly and directly calculating a length of a dichotomous tree without having to resort to branch length calculations. This direct calculation (DC) method applies to the complete final topology, giving equal importance to each branch after a dichotomy. According to this method, the tree length S _DC is S _DC =∑ _i ∑ _j (D _ij /2 ^Bij ) = (∑ _i<j ∑D _ij 2 ^Bmax−Bij )/2 ^{Bmax −1} where D _ij is the observed distance between taxa i and j, B _ij is the number of branches connecting i and j, Bmax is the greatest B _ij in the tree, and the powers of two are due to the dichotomy of the tree. This tree length expression may be used as a rapid method for selecting the shortest tree from a set of hypothetical or subobtimal trees. Received: 2 March 2000 / Accepted: 24 March 2000     

Molecular phylogeny of Macrolycus (Coleoptera: Lycidae) with description of new species from China

Macrolycus is a genus of net‐winged beetles with 69 species distributed in the eastern Palearctic and northernmost part of the Oriental region. The first molecular phylogeny of Macrolycus was produced using an rrnL + tRNA‐Leu + nad1 mtDNA fragment. The major lineages and species limits were identified with morphology and molecular data. We propose that Cerceros is a subgenus of Macrolycus to enable identification of all adult specimens in the genus without DNA sequencing. Two species groups are proposed in Macrolycus s. str. and six in Cerceros. Additionally, twelve Macrolycus species are newly described from China: M. aquilinus, M. baihualingensis, M. bicolor, M. guangxiensis, M. jianfenglingensis, M. kuatunensis, M. lizipingensis, M. parvus, M. phoeniceus, M. rhodoneurus, M. rosaceus and M. sichuanensis. Macrolycus holzschuhi is proposed to be a junior subjective synonym of M. jeanvoinei. The highest diversity of Macrolycus is found in southern China. The species from the main islands of Japan are placed in two species groups: M. excellens is a sister to remaining species of the M. murzini group and the M. flabellatus group is a monophylum of closely related species in a sister position to the M. bicolor group.     

A simple chlorophyll fluorescence parameter that correlates with the rate coefficient of photoinactivation of Photosystem II

A method of partitioning the energy in a mixed population of active and photoinactivated Photosystem II (PS II) complexes based on chlorophyll fluorescence measurements is presented. There are four energy fluxes, each with its quantum efficiency: a flux associated with photochemical electron flow in active PS II reaction centres (J_{PS II}), thermal dissipation in photoinactivated, non-functional PS IIs (J_NF), light-regulated thermal dissipation in active PS IIs (J_NPQ) and a combined flux of fluorescence and constitutive, light-independent thermal dissipation (J_f,D). The four quantum efficiencies add up to 1.0, without the need to introduce an ‘excess’ term E, which in other studies has been claimed to be linearly correlated with the rate coefficient of photoinactivation of PS II (k_pi). We examined the correlation of k_pi with various fluxes, and found that the combined flux (J_NPQ + J_f,D= J_pi) is as well correlated with k_pi as is E. This combined flux arises from F_s/F_m^′, the ratio of steady-state to maximum fluorescence during illumination, which represents the quantum efficiency of combined non-photochemical dissipation pathways in active PS IIs. Since F_s/F_m^′ or its equivalent, J_pi, is a likely source of events leading to photoinactivation of PS II, we conclude that F_s/F_m^′ is a simple predictor of k_pi.     

Responses of genotypes from species of Trifolium, Ornithopus, Biserrula and Hedysarum to a highly virulent race of Phytophthora clandestina and new sources of resistance

Thirty‐six genotypes, including 15 cultivars and 10 breeding lines of Trifolium subterraneum, a single genotype of each of seven other species of Trifolium (viz. Trifolium dasyurum, Trifolium glanduliferum, Trifolium incarnatum, Trifolium michelanium, Trifolium purpureum, Trifolium spumosum and Trifolium vesiculosum), Biserrula pelecinus, Hedysarum coronarium, Ornithopus compressus and Ornithopus sativus were screened under controlled environmental conditions for resistance to root disease caused by the most pathogenic race of Phytophthora clandestina occurring in Australia, namely race 177. This is the first time any of these genera/species other than T.subterraneum has ever been screened for its response to P. clandestina. The root disease caused by P.clandestina is the first report of susceptibility to this pathogen for the seven other species of Trifolium and also for B.pelecinus, H.coronarium and O.sativus. Within T.subterraneum, a very high level of resistance was identified in cvs Denmark, Junee and Meteora [scores ≤1.5 (0–5 scale where 0 = no disease) across two separate screening tests] and in the breeding lines SL027 and SM023 (scores ≤1.3 across two separate screening tests). Six of the seven other species of Trifolium (viz. T.dasyurum, T.glanduliferum, T.incarnatum, T.michelanium, T.purpureum and T.spumosum) showed a high level of resistance (scores ≤0.8 across two separate screening tests), while T.vesiculosum showed a disease score of ≤1.2 across both screening tests. O.compressus showed no disease in either test, and O.sativus showed a disease score of ≤0.7 across both screening tests. H.coronarium was susceptible with a disease score of ≤2.8 across two separate screening tests, while B.pelecinus was highly susceptible with disease scores of 3.5 and 4.6 in these tests. The high levels of resistance identified against P.clandestina are useful sources of resistance that can be exploited commercially, either directly to minimise damage from this disease or as parents in breeding programs to develop cultivars within the genera/species tested with improved resistance to this highly pathogenic race of P.clandestina.     

Phylogenetic relationships within the South American fish family Anostomidae (Teleostei,Ostariophysi, Characiformes)

Analysis of a morphological dataset containing 152 parsimony‐informative characters yielded the first phylogenetic reconstruction spanning the South American characiform family Anostomidae. The reconstruction included 46 ingroup species representing all anostomid genera and subgenera. Outgroup comparisons included members of the sister group to the Anostomidae (the Chilodontidae) as well as members of the families Curimatidae, Characidae, Citharinidae, Distichodontidae, Hemiodontidae, Parodontidae and Prochilodontidae. The results supported a clade containing Anostomus, Gnathodolus, Pseudanos, Sartor and Synaptolaemus (the subfamily Anostominae sensu Winterbottom) albeit with a somewhat different set of relationships among the species within these genera. Anostomus as previously recognized was found to be paraphyletic and is split herein into two monophyletic components, a restricted Anostomus and the new genus Petulanos gen. nov. , described herein. Laemolyta appeared as sister to the clade containing Anostomus, Gnathodolus, Petulanos, Pseudanos, Sartor and Synaptolaemus. Rhytiodus and Schizodon together formed a well‐supported clade that was, in turn, sister to the clade containing Anostomus, Gnathodolus, Laemolyta, Petulanos, Pseudanos, Sartor and Synaptolaemus. Anostomoides was sister to the clade formed by these nine genera. Leporinus as currently defined was not found to be monophyletic, although certain clades within that genus were supported, including the species with subterminal mouths in the former subgenus Hypomasticus which we recognize herein as a genus. Abramites nested in Leporinus, and Leporellus was found to be the most basal anostomid genus. The presence of cis‐ and trans‐Andean species in Abramites, Leporellus, Leporinus and Schizodon, all relatively basal genera, suggests that much of the diversification of anostomid species pre‐dates the uplift of the Andean Cordilleras circa 11.8 million years ago. Several important morphological shifts in anostomid evolution are illustrated and discussed, including instances of convergence and reversal. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 70–210.