II genere Amanita Pers. ex Fr. nei dintorni di Roma

Abstract

The genus Amanita Pers. ex Fr. in Rome neighbourood. — The presence of the genus Amanita in Rome neighbourood, small district, with vegetation and soil diversified, has been studied. The list includes 30 entities (A. caesarea, A. argentea°, A. nivalis, A. vaginata, A. vaginata var. cinerea°, A. fulva, A. crocea°, A. umbrinolutea°, A. lividapallescens°, A. strangulata, A. junquillea, A. eliae°, A. muscaria, A. pantherina, A. alba, A. phalloides, A. phalloides var. alba, A. verna, A. virosa, A. citrina, A. citrina var. alba°, A. porphyria°, A. rubescens, A. spissa. A. excelsa, A. aspera, A. vittadini, A. codinae°, A. strobiliformis, A. boudieri°), 11 new also for latium (°), among these A. codinae and A. vaginata var. cinerea hitherto not found in Italy. At last, the genus in whole region is examined.     

Resistance to groundnut rosette disease in wild Arachis species

One hundred and sixteen accessions representing 28 species in the genus Arachis were evaluated for resistance to groundnut rosette disease using an infector row technique during the 1996/97, 1997/98, 1998/99 and 1999/2000 growing seasons at Chitedze, Malawi. Of these, a total of 25 accessions belonging to Arachis diogoi (1 accession), A. hoehnei (2), A. kretschmeri (2), A. cardenasii (2), A. villosa (1), A. pintoi (5), A. kuhlmannii (2), A. appressipila (3), A. stenosperma (5), A. decora (1), and A. triseminata (1) showed resistance to the groundnut rosette disease. No visible disease symptoms were observed in several accessions belonging to A. appressipila, A. cardenasii, A. hoehnei, A. kretschmeri, A. villosa, A. pintoi, A. kuhlmannii, and A. stenosperma. Some accessions in A. appressipila, A. diogoi, A. stenosperma, A. decora, A. triseminata, A. kretschmeri, A. kuhlmannii, and A. pintoi were resistant to all three components of rosette, Groundnut rosette ass is tor virus (GRAV), Groundnut rosette virus (GRV) and its satellite RNA (sat. RNA). Two accessions in A. stenosperma and one accession in A. kuhlmannii showed the presence of all three components of the rosette disease. Several wild Arachis accessions were resistant to GRAV. All the accessions of A. batizocoi (4), A. benensis (2), A. duranensis (46), A. dardani (1), A. ipaensis (1), A. magna (1), A. monticola (3), A. oteroi (1), A. pusilla (4), and A. valida (2) were susceptible to rosette disease. In all these accessions, infected plants were chlorotic and severely stunted. The value of exploitation of the resistance in wild Arachis species in rosette resistance breeding programmes is discussed.     

COMPOSITION OF VOLATILES IN RELATION TO TAXONOMY OF AMERICAN ALLIUMS

The North American species of Allium exclusive of A. schoenoprasum and A. tricoccum of Old World affinity are grouped on the basis of morphological similarity into eight discontinuous species alliances typified by A. acuminatum, A. campanulatum, A. canadense, A. cernuum, A. falcifolium, A. kunthii, A. sanbornii, and A. validum, respectively. Representatives of each of these alliances were compared with respect to volatile constituents responsible for characteristic odors by means of gas chromatography. Results indicate that these volatiles provide evidence of relationship useful in the classification of alliums. Uniformity was found in composition of volatiles in the representatives of the A. canadense, A. cernuum, A. kunthii, and A. sanbornii alliances. Variation was observed in the A. acuminatum, A. campanulatum, and A. falcifolium alliances. A. validum was the only species of its alliance studied. Vapors of A. validum contain mostly n-propyl sulfides (onion-like odor) as does the cultivated A. cepa. Methyl sulfides (cabbage-like odor) predominate in the A. sanbornii alliance. A few species of the A. acuminatum and A. falcifolium alliances contain mainly allyl sulfides (garlic-like odor).     

A new classification for the subgenera of the genus Acanthophthirius Perkins,with descriptions of twelve new taxa (Acarina,Trombidiformes, Myobiidae)

The myobiid genus Acanthophthirius Perkins, to date comprising four subgenera, is reviewed and divided into just two subgenera, the nominate subgenus and Myotimyobia Fain. The male genital shield and female opisthogastric sclerites, which are here considered to be part of female genitalia, are adopted as the criteria for dividing the subgenera. These structures are essentially the same in form and position in the subgenus Acanthopthirius in its revised sense, while they are both more heterogeneous in species of the redefined subgenus Myotimyobia. The subgenera Acanthophthirius Fain and Chiromyobia Fain are thought to represent species-groups in the nominate subgenus, named respectively the etheldredae and miniopteri groups. The following one new subspecies and 11 new species are described: A. (A.) womersleyi eptesicus, A. (A.) glauconycteris, A. (A.) mauritaniensis, A. (A.) philetoris, A. (A.) otonycteris, A. (A.) steatocaudatus, A. (A.) nyctophilis, A. (M.) vagus, A. (M.) longus A. (M.) baueris, A. (A.) hesperopteris (female only) and A. (M.) pixonixeos (female only). A. (M.) hanensis is synonymised with A. (M.) namurensis, and A. (M.) capacini is emended to A. (M.) capaccinii and relegated to a subspecies of A. (M.) myotis. All the known and new species are assigned to their respective subgenera and shown in a table. Incongruent host-relationships of some of the mites are clarified, although not completely solved, by the introduction of the new classification for the subgenera.     

A multigene approach to determine the molecular phylogeography of Argiope mangal and Argiope dang (Araneae: Araneidae) and their genetic relationships with the Argiope aetherea species group

The genus Argiope represents a collection of morphologically diverse orb-weaving spiders with a cosmopolitan distribution. Argiope dang and A. mangal are two Southeast Asian species that share remarkably similar morphological characteristics congeneric to the A. aetherea species group. However, in previous investigations, molecular data have not been used for the taxonomic categorization of A. dang and A. mangal. Additionally, gene flow between populations of A. dang and of A. mangal in their natural habitats has not been adequately studied. In the present study, mitochondrial 16S, COI and COII markers were used in addition to the nuclear H3 gene to elucidate the relationships between A. dang, A. mangal and various congeners within the A. aetherea species group. The haplotype diversity of A. dang and A. mangal was also investigated. Based on our molecular results, the A. aetherea species group was composed of three genetic lineages: (i) [A. dang - (A. radon - A. picta)] - [A. modesta - A. aetherea]; (ii) A. mangal; and (iii) [(A. jinghongensis - A. aetheroides) - A. versicolor]. Haplotype analyses revealed a lack of gene flow between A. mangal populations in Peninsular Malaysia and those in Singapore. Populations of A. dang showed isolation-by-distance throughout the range of the species from Laos to Singapore. In this study for the first time, genetic data of A. mangal were reported for specimens collected from its type locality, Singapore. Four new distribution records were also reported: A. dang in Peninsular Malaysia and Cambodia; A. modesta in Bali, Indonesia; and A. jinghongensis in Peninsular Malaysia.     

土壤水分及其垂直分布对内蒙古草原冰草和冷蒿竞争的影响

内蒙古退化冷蒿草原围封恢复演替3-4年,植物群落更替出现半灌木冷蒿（Artemisia frigida）向禾草冰草（Agropyron cristatum）群落突然转变的现象,这对内蒙古草原植被恢复具有积极的作用,但目前关于冰草-冷蒿演替和竞争机制的研究鲜见报道。水分作为草原植被生长的主要限制因子,是影响群落演替的重要因素。气候干旱和过度放牧导致草原土壤水分垂直分布发生明显变化。由于冰草和冷蒿的根系分布深浅不同,土壤水分垂直变化可能会影响冰草-冷蒿的竞争。为探讨土壤水分及其垂直分布对冰草和冷蒿竞争的影响,本盆栽试验设置冰草、冷蒿单种以及混种处理,并进行不同土壤深度（0-30cm,30-60cm）的水分处理（上干下湿、上湿下干、上干下干）,结果表明：（1）与冷蒿相比,冰草受土壤水分变化影响显著,相对于上干下干处理,冰草在湿润（上干下湿或者上湿下干）处理的地上、地下生物量均显著增加,而冷蒿没有显著变化;（2）上干下湿和上湿下干处理间,冰草、冷蒿的地上、地下总生物量和根长差异均不显著;（3）不同水分处理,冰草和冷蒿的根系均可分布在30-60cm土壤中,且土壤30-60cm层冰草单种的根生物量和根长显著高于冷蒿单种;（4）相对竞争强度和竞争攻击力系数表明：湿润处理冰草的竞争力大于冷蒿;上干下干处理冷蒿的竞争力大于冰草。土壤水分变化引起冰草、冷蒿的明显竞争,上湿下干与上干下湿处理间冰草与冷蒿竞争力差异不显著。由于冰草和冷蒿均为多年生物种,冰草-冷蒿的竞争实验仍需在今后的研究中反复地验证。     

Identification of Residues in the 558-Loop of Factor VIIIa A2 Subunit That Interact with Factor IXa

Factor VIIIa is comprised of A1, A2, and A3C1C2 subunits. Several lines of evidence have identified the A2 558-loop as interacting with factor IXa. The contributions of individual residues within this region to inter-protein affinity and cofactor activity were assessed following alanine scanning mutagenesis of residues 555–571 that border or are contained within the loop. Variants were expressed as isolated A2 domains in Sf9 cells using a baculovirus construct and purified to >90%. Two reconstitution assays were employed to determine affinity and activity parameters. The first assay reconstituted factor Xase using varying concentrations of A2 mutant and fixed levels of A1/A3C1C2 dimer purified from wild type (WT), baby hamster kidney cell-expressed factor VIII, factor IXa, and phospholipid vesicles to determine the inter-molecular K_d for A2. The second assay determined the K_d for A2 in factor VIIIa by reconstituting various A2 and fixed levels of A1/A3C1C2. Parameter values were determined by factor Xa generation assays. WT A2 expressed in insect cells yielded similar K_d and k_cat values following reconstitution as WT A2 purified from baby hamster kidney cell-expressed factor VIII. All A2 variants exhibited modest if any increases in K_d values for factor VIIIa assembly. However, variants S558A, V559A, D560A, G563A, and I566A showed >9-fold increases in K_d for factor Xase assembly, implicating these residues in stabilizing A2 association with factor IXa. Furthermore, variants Y555A, V559A, D560A, G563A, I566A, and D569A showed >80% reduction in k_cat for factor Xa generation. These results identify residues in the 558-loop critical to interaction with factor IXa in Xase.     

Data on chromosome numbers in Aster (Asteraceae), with comments on the status and relationships of certain North American species

Chromosome counts are presented for more than 250 populations ofAster representing 56 species and eight spontaneous interspecific hybrids. Species are listed according to the infrageneric classification system presented in the preceding paper which utilizes basic chromosome numbers as the pivotal diagnostic character. Fundamental to the classification is an ecological species concept. The list is augmented by a series of comments on field observations and on the examination of types. Six older names previously placed in synonymy or recognized at an inferior rank are reinstated at the species level:A. brachypholis, A.firmus, A. fragilis, A. longifolius, A. simmondsii andA. tardiflorus. Two taxa included as species in current manuals of the eastern North American flora are reduced in status to subspecies rank underA. cordifolius. Putative hybrid status is assigned to four taxa previously treated and originally published as species:A. × coerulescens (= A. praealtus × A. simplex, A. × interior (= A. simplex × A. tradescantii, A. × maccallae (= A. ciliolatus × A. subspicatus) and A. × subgeminatus (= A. ciliolatus × A. tardiflorus). With new data available, the basic chromosome number ofx = 8 has now been confirmed for all species ofAster sectionHeterophylli, except the Mexican A.coahuilensis.     

CHROMOSOME NUMBERS OF NORTH AMERICAN SPECIES OF ANTENNARIA GAERTNER (ASTERACEAE: INULEAE)

Chromosome numbers are presented for 99 populations of 13 species of Antennaria, including A. plantaginifolia, A. neglecta, A. virginica, A. solitaria, A. racemosa, A. corymbosa. A. rosea, A. media, A. Parlinii, A. fallax, A. neodioica, A. canadensis, and A. petaloidea. Four species from the eastern United States (A. plantaginifolia, A. neglecta, A. solitaria, and A. virginica) were determined as diploid (n = 14), and these are all sexual. Diploid counts were also obtained for two sexual species (A. racemosa and A. corymbosa) from the western United States. Chromosome counts are presented for two heteroploid agamic complexes occurring in the eastern United States; these include what have traditionally been referred to as A. Parlinii, A. fallax, A. neodioica, A. canadensis, and A. petaloidea. Determinations of 2n = 56, 70, 84, and 112 were obtained for the A. Parlinii and A. fallax groups, where 2n = 84 had been the only number previously reported. Numbers of 2n = 84 were confirmed for A. petaloidea and A. canadensis and 2n = 56 for A. neodioica. The western United States polyploid species (A. rosea and A. media) are reported as 2n = 56. The presence of apomixis is correlated with polyploidy. The distribution of chromosome numbers in eastern United States Antennaria demonstrates that two diploids and many polyploids occur above the glacial margin, and thus there is an increase in the frequency of polyploidy with latitude. Colonization of the glaciated region by Antennaria following the recession of the Wisconsin ice sheet is also discussed. Many of the polyploids occur only in the glaciated region, thus suggesting a recent origin for these cytotypes. There is evidence indicating that the original base number in Antennaria may be x = 7.     

Crucial factors determining the spatio-temporal distribution patterns of threeAthalia sawflies feeding on common cruciferous plants

Three Athalia sawflies, A. japonica, A. rosae and A. infumata, feeding on cruciferous plants, coexist in Japan. However, it is not known what ecological strategies they use and what environmental factors are crucial to such strategies. I attempted to explain these questions by examining the relationship between the spatio-temporal distribution patterns of three Athalia sawflies and their habitats in three districts (Lowland, Intermediate and Mountain). The three sawflies have different spatio-temporal distribution patterns, though they usually used common cruciferous plants. A. japonica was abundant in spring and autumn but disappeared during summer in all the districts. In the Lowland, populations of A. rosae and A. infumata, like that of A. japonica, crashed in summer. However A. rosae occurred mainly in summer in the Intermediate and Mountain. Although A. infumata occurred in the same seasons as A. rosae in all districts, population levels of A. infumata were always lower than those of A. rosae. The crucial factors controlling their population patterns were the availability of host plants and temperature. Population crashes of A. rosae and A. infumata were due to food depletion, and those of A. japonica were due to heat stress. On the other hand, their population patterns may be interpreted as phenological synchronization with their original host plants, though they all existed on common cruciferous plants. The three sawflies may have evolved different strategies to escape from unfavorable habitat conditions. Such strategies are speculated to be summer diapause in A. japonica, long distance migration in A. rosae, and local dispersal in A. infumata.     

No correlation between time-linked plasma and CSF Aβ levels

Plasma β-amyloid protein (Aβ) isoforms are considered potential biomarkers for Alzheimer's disease (AD) and dementia. The relation between plasma and cerebrospinal fluid (CSF) levels of Aβ isoforms remains unclear. In order to identify possible correlations between Aβ levels in plasma and CSF we determined Aβ levels in time-linked plasma and CSF samples. Aβ concentrations in plasma (Aβ_1–42 and Aβ_N–42) and CSF (Aβ_1–42) samples from 49 AD patients, 47 non-Alzheimer's disease dementia (NONAD) patients, 39 MCI patients and 29 controls were determined using a multi-parameter fluorimetric bead-based immunoassay using xMAP^® technology (for plasma) and a conventional single-parameter ELISA (for CSF). Plasma Aβ_1–42 concentrations did not correlate with CSF Aβ_1–42 concentrations in the total study population, or in the different diagnostic groups. No correlations between plasma Aβ_N–42 and CSF Aβ_1–42 levels were found either. The CSF/serum albumin index did not show any significant differences between AD, NONAD, MCI and controls.These results suggest that the Aβ levels in plasma are independent of the Aβ levels in CSF both in dementia and controls. The fact that CSF and plasma Aβ do not correlate in patients as well as controls and no significant differences in plasma Aβ_1–42 or Aβ_N–42 between patients and controls can be detected hampers the diagnostic utility of the plasma Aβ levels as biomarkers for dementia.     

Leaf anatomy and the occurrence of false veins in Asplenium (Aspleniaceae, Pteridophyta)

False veins in African afro-alpine (2000–4700 m) Asplenium species with long creeping rhizomes and highly dissected leaves are morphologically and anatomically similar to true veins but differ in the absence of a vascular bundle. False veins in Aspleniaceae may have originated by the fusion of leaf lobes, and are more similar to those in Angiopteris and Thelypteris than to those in Davallia and Hymenophyllaceae. Because false veins are long and extend from the leaf margin to the junction of the neighbouring true veins in A. actiniopteroides , A. goetzei , A. majus , A. praegracile , A . sp. nov. and A. uhligii , but short, not reaching this junction in A. decompositum , A. demerkense , A. kassneri , A. linckii and A. mildbraedii , and even absent in A. aethiopicum , A. lademannianum , A. simii , A. stipicellatum and A. volkensii , they can be used for identification in this enigmatic group of ferns.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 145 , 187–194.     

Introgression and pyramiding into common bean market class fabada of genes conferring resistance to anthracnose and potyvirus

Anthracnose and bean common mosaic (BCM) are considered major diseases in common bean crop causing severe yield losses worldwide. This work describes the introgression and pyramiding of genes conferring genetic resistance to BCM and anthracnose local races into line A25, a bean genotype classified as market class fabada. Resistant plants were selected using resistance tests or combining resistance tests and marker-assisted selection. Lines A252, A321, A493, Sanilac BC6-Are, and BRB130 were used as resistance sources. Resistance genes to anthracnose (Co-2 ^C , Co-2 ^A252 and Co-3/9) and/or BCM (I and bc-3) were introgressed in line A25 through six parallel backcrossing programs, and six breeding lines showing a fabada seed phenotype were obtained after six backcross generations: line A1258 from A252; A1231 from A321; A1220 from A493; A1183 and A1878 from Sanilac BC6-Are; and line A2418 from BRB130. Pyramiding of different genes were developed using the pedigree method from a single cross between lines obtained in the introgression step: line A1699 (derived from cross A1258 × A1220), A2438 (A1220 × A1183), A2806 (A1878 × A2418), and A3308 (A1699 × A2806). A characterization based on eight morpho-agronomic traits revealed a limited differentiation among the obtained breeding lines and the recurrent line A25. However, using a set of seven molecular markers linked to the loci used in the breeding programs it was possible to differentiate the 11 fabada lines. Considering the genetic control of the resistance in resistant donor lines, the observed segregations in the last backcrossing generation, the reaction against the pathogens, and the expression of the molecular markers it was also possible to infer the genotype conferring resistance in the ten fabada breeding lines obtained. As a result of these breeding programs, genetic resistance to three anthracnose races controlled by genes included in clusters Co-2 and Co-3/9, and genetic resistance to BCM controlled by genotype I + bc-3 was combined in the fabada line A3308.     

APOBEC3G Restricts HIV-1 to a Greater Extent than APOBEC3F and APOBEC3DE in Human Primary CD4+ T Cells and Macrophages

APOBEC3 proteins inhibit HIV-1 replication in experimental systems and induce hypermutation in infected patients; however, the relative contributions of several APOBEC3 proteins to restriction of HIV-1 replication in the absence of the viral Vif protein in human primary CD4⁺ T cells and macrophages are unknown. We observed significant inhibition of HIV-1Δvif produced in 293T cells in the presence of APOBEC3DE (A3DE), APOBEC3F (A3F), APOBEC3G (A3G), and APOBEC3H haplotype II (A3H HapII) but not APOBEC3B (A3B), APOBEC3C (A3C), or APOBEC3H haplotype I (A3H HapI). Our previous studies showed that Vif amino acids Y⁴⁰RHHY⁴⁴ are important for inducing proteasomal degradation of A3G, whereas amino acids ¹⁴DRMR¹⁷ are important for degradation of A3F and A3DE. Here, we introduced substitution mutations of ⁴⁰YRHHY⁴⁴ and ¹⁴DRMR¹⁷ in replication-competent HIV-1 to generate vif mutants NL4-3 YRHHY>A5 and NL4-3 DRMR>A4 to compare the antiviral activity of A3G to the combined antiviral activity of A3F and A3DE in activated CD4⁺ T cells and macrophages. During the first 15 days (round 1), in which multiple cycles of viral replication occurred, both the NL4-3 YRHHY>A5 and NL4-3 DRMR>A4 mutants replicated in activated CD4⁺ T cells and macrophages, and only the NL4-3 YRHHY>A5 mutant showed a 2- to 4-day delay in replication compared to the wild type. During the subsequent 27 days (round 2) of cultures initiated with peak virus obtained from round 1, the NL4-3 YRHHY>A5 mutant exhibited a longer, 8- to 10-day delay and the NL4-3 DRMR>A4 mutant exhibited a 2- to 6-day delay in replication compared to the wild type. The NL4-3 YRHHY>A5 and NL4-3 DRMR>A4 mutant proviruses displayed G-to-A hypermutations primarily in GG and GA dinucleotides as expected of A3G- and A3F- or A3DE-mediated deamination, respectively. We conclude that A3G exerts a greater restriction effect on HIV-1 than A3F and A3DE.     

Two new species of <Emphasis Type="Italic">Anthobothrium</Emphasis> van Beneden, 1850 (Tetraphyllidea: Phyllobothriidae) from carcharhinid sharks,with a redescription of <Emphasis Type="Italic">Anthobothrium laciniatum</Emphasis> Linton, 1890

Anthobothrium laciniatum Linton, 1890 is redescribed based on specimens taken from the dusky shark Carcharhinus obscurus (Lesueur) collected from the Northwestern Atlantic Ocean, and a neotype is designated. A. laciniatum differs from A. cornucopia van Beneden, 1850, A. altavelae Euzet & Ben Hassine, 2002, A. lesteri Williams, Burt & Caira, 2004 and A. spinosum Subhapradha, 1955 in total length. It further differs from A. cornucopia, A. altavelae and A. spinosum in proglottid number, and differs from A. galeorhini Suriano, 2002, A. cornucopia, and A. spinosum in testis number. A. lyndoni n. sp. is described from the sandbar shark C. plumbeus (Nardo). This new species differs from A. laciniatum in ovarian width and from A. cornucopia, A. altavelae, A. galeorhini and A. spinosum in the total number of proglottids. It further differs from A. cornucopia, A. galeorhini, and A. spinosum in total length, and from A. cornucopia and A. galeorhini in the number of testes. A. lyndoni n. sp. differs from A. lesteri in bothridial muscle and ovarian morphology. Anthobothrium caseyi n. sp. is described from Prionace glauca (Linnaeus). This new species differs conspicuously from the other six species of Anthobothrium van Beneden, 1850 (sensu stricto) in the shape of its proglottid laciniations. The taxonomic status of 43 species that have been associated with Anthobothrium is addressed. Taxonomic actions regarding Anthobothrium during the past century have resulted in a polyphyletic taxon.     

Structural Basis for Aβ1-42 Toxicity Inhibition by Aβ C-Terminal Fragments: Discrete Molecular Dynamics Study

Amyloid β-protein (Aβ) is central to the pathology of Alzheimer's disease. Of the two predominant Aβ alloforms, Aβ_1-40 and Aβ_1-42, the latter forms more toxic oligomers. C-terminal fragments (CTFs) of Aβ were recently shown to inhibit Aβ_1-42 toxicity in vitro. Here, we studied Aβ_1-42 assembly in the presence of three effective CTF inhibitors and an ineffective fragment, Aβ_21-30. Using a discrete molecular dynamics approach that recently was shown to capture key differences between Aβ_1-40 and Aβ_1-42 oligomerization, we compared Aβ_1-42 oligomer formation in the absence and presence of CTFs or Aβ_21-30 and identified structural elements of Aβ_1-42 that correlated with Aβ_1-42 toxicity. CTFs co-assembled with Aβ_1-42 into large heterooligomers containing multiple Aβ_1-42 and inhibitor fragments. In contrast, Aβ_21-30 co-assembled with Aβ_1-42 into heterooligomers containing mostly a single Aβ_1-42 and multiple Aβ_21-30 fragments. The CTFs, but not Aβ_21-30, decreased the β-strand propensity of Aβ_1-42 in a concentration-dependent manner. CTFs and Aβ_21-30 had a high binding propensity to the hydrophobic regions of Aβ_1-42, but only CTFs were found to bind the Aβ_1-42 region A2-F4. Consequently, only CTFs but not Aβ_21-30 reduced the solvent accessibility of Aβ_1-42 in region D1-R5. The reduced solvent accessibility of Aβ_1-42 in the presence of CTFs was comparable to the solvent accessibility of Aβ_1-40 oligomers formed in the absence of Aβ fragments. These findings suggest that region D1-R5, which was more exposed to the solvent in Aβ_1-42 than in Aβ_1-40 oligomers, is involved in mediating Aβ_1-42 oligomer neurotoxicity.     

Karyological notes on eight species of Achillea L. (Asteraceae, Santolinoideae) from Turkey

The chromosome number and morphology of eight species belonging to the section Santolinoideae of the genus Achillea L. (Asteraceae) were investigated using karyological techniques. The species studied were Achillea cucullata (Hausskn.) Bornm., A. vermicularis Trin., A. monocephala Boiss. & Bal., A. boissieri (Hausskn.) Bornm., A. santolina L., A. gypsicola Hub.-Mor., A. goniocephala Boiss. & Bal., and A. spinulifolia Fenzl ex Boiss. In these species, the chromosome numbers were 2 n  = 18 in A. vermicularis , A. monocephala , and A. boissieri , 2 n  = 18A + 1B in A. spinulifolia , 2 n  = 36 in A. cucullata and A. santolina , and 2 n  = 54 in A. gypsicola and A. goniocephala . All of the chromosomes had median point (M), median region (m), or submedian (sm) centromeres. An increase in asymmetry was not observed in the karyotypes of the species.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 573–580.     

Perforin Promotes Amyloid Beta Internalisation in Neurons

Studies on the mechanisms of neuronal amyloid-β (Aβ) internalisation are crucial for understanding the neuropathological progression of Alzheimer’s disease (AD). We here investigated how extracellular Aβ peptides are internalised and focused on three different pathways: (i) via endocytic mechanisms, (ii) via the receptor for advanced glycation end products (RAGE) and (iii) via the pore-forming protein perforin. Both Aβ₄₀ and Aβ₄₂ were internalised in retinoic acid differentiated neuroblastoma (RA-SH-SY5Y) cells. A higher concentration was required for Aβ₄₀ (250 nM) compared with Aβ₄₂ (100 nM). The internalised Aβ₄₀ showed a dot-like pattern of distribution whereas Aβ₄₂ accumulated in larger and distinct formations. By confocal microscopy, we showed that Aβ₄₀ and Aβ₄₂ co-localised with mitochondria, endoplasmic reticulum (ER) and lysosomes. Aβ treatment of human primary cortical neurons (hPCN) confirmed our findings in RA-SH-SY5Y cells, but hPCN were less sensitive to Aβ; therefore, a 20 (Aβ₄₀) and 50 (Aβ₄₂) times higher concentration was needed for inducing uptake. The blocking of endocytosis completely inhibited the internalisation of Aβ peptides in RA-SH-SY5Y cells and hPCN, indicating that this is a major pathway by which Aβ enters the cells. In addition, the internalisation of Aβ₄₂, but not Aβ₄₀, was reduced by 55 % by blocking RAGE. Finally, for the first time we showed that pore formation in cell membranes by perforin led to Aβ internalisation in hPCN. Understanding how Aβ is internalised sheds light on the pathological role of Aβ and provides further ideas of inhibitory strategies for preventing Aβ internalisation and the spreading of neurodegeneration in AD.     

Genomic in situ hybridization inArachis (Fabaceae) identifies the diploid wild progenitors of cultivated (A. hypogaea) and related wild (A. monticola) peanut species

Genomic in situ hybridization offers a powerful tool for investigating genome organisation and evolution of taxa known, or suspected, to be allopolyploids. The question of the diploid progenitors of cultivated peanut (Arachis hypogaea, 2n=4x=40) has been the subject of numerous studies at cytogenetical, cytochemical, biochemical and molecular levels, but no definitive conclusions have been reached. The biotinylated total genomic DNA from potential diploidArachis species were separately hybridized in situ to root tip chromosomes ofA. hypogaea and wild speciesA. monticola (2n=4x=40) without or mixed with an excess of unlabelled DNA from the species not used as a probe. Among the range of different species combinations used, the strong and uniform signals given by labelledA. ipaensis DNA when hybridized toA. hypogaea andA. monticola in combination with unlabelledA. villosa DNA indicates that overall molecular composition of twenty chromosomes ofA. hypogaea andA. monticola is very similar toA. ipaensis chromosomes. ProbingA. hypogaea andA. monticola chromosomes with labelled genomic DNA fromA. villosa mixed with unlabelled DNA fromA. ipaensis likewise labelled strongly and uniformly the other twenty chromosomes. BarringA. ipaensis, all the diploidArachis species presently investigated had characteristic centromeric bands in the twenty chromosomes within the complement indicating a clear division ofA. ipaensis from other species. InA. hypogaea andA. monticola only twenty chromosomes showed centromeric bands. These results (i) confirm the allopolyploid nature ofA. hypogaea andA. monticola, (ii) strongly support the view that wildA. monticola and cultivatedA. hypogaea are very closely related, and (iii) indicate thatA. villosa andA. ipaensis are the diploid wild progenitors of the tetraploid species studied. The present results also reveal that the nucleolus organizing region (NOR) originating fromA. villosa alone is expressed in the two tetraploid species.     

Chemotaxonomic aspects of some Acacia gum exudates from series Juliflorae*

Data for the chemical composition of the gum exudates from Acacia acradenia, A. aneura, A. acuminata, A. beauverdiana, A. coolgardiensis, A. kempeana, A. microneura, A. resinomarginea, A. stereophylla and A. torulosa are presented. Comparisons with the data reported previously for other species of the series Juliflorae, viz. A. auriculiformis, A. holosericea, A. leptostachya, A. mangium and A. pubifolia confirm that the gums from this series have interesting combinations of chemical properties that are unusual in Acacia. The data do not offer much chemotaxonomic support for the groupings of the Juliflorae suggested by Bentham (1864). On the basis of their gross morphological features, the species under consideration are re-grouped in a way that is also better supported chemically.