Electron Transfer and Photoprotective Properties of Melanins in Solution

The polyquinoid nature of eumelanin(s) enables them to couple oxidation of electron donors with the reduction of electron acceptors. We have studied the ability of synthetic (Sigma) and “biological” (cuttlefish sepia) melanins to mediate electron transfer between hydroxybenzene donors (tyrosine, dopa, chemical depigmenters) and model acceptors (ferricyanide, tyrosinase). 1) Depending on the reductant, melanin either retards or accelerates ferricyanide reduction. Reaction kinetics are consistent with a mechanism involving non-interactive binding of both hydroxybenzene and ferricyanide to melanin prior to coupled electron transfer. 2) Melanins also act as an electron conduit in markedly accelerating the tyrosinase-catalyzed oxygenation of p-hydroxyanisole (MMEH). The active species appears to be a complex between melanin and MMEH. The magnitude of both effects depend on the type of melanin as well as its oxidation state. Sepia (eu)melanin appears to protect against UV-induced damage to acid-soluble collagen, as judged by irreversible loss of intrinsic collagen fluorescence. Photoprotection against this type of damage appears primarily to involve optical absorption/scattering by the pigment.     

STUDIES IN THE INTERACTIONS BETWEEN SPECIES OF VERTICILLIUM

It is shown that five parasitic species of Verticillium , viz. V. alboatrum, V. Dahliae, V. ticorpus, V. nigrescens and V. nubilum , developed together on agar media or wheat grains as saprophytes without causing mutual antagonism but, when these were injected together, as a mixed spore suspension, into antirrhinum and tomato, suppression of V. tricorypus, V. nigescens and V. nubilum by either one or other of the remaining two invariably resulted. The two most virulent pathogens, V. alboatrum and V. Dahliae , were not recoverable from soil after the elapse of 6 months from the time of inoculation; while the other three less virulent pathogens could be isolated after about 12 months in the soil. It is concluded that V. alboatrurn and V. Dahliae may be described as 'root inhabiting' and V. nigrescens and V. nubilurn as 'soil inhabiting', while V. tricorpus may be considered as an intermediate type.     

Host/parasite relations up to the time of tuber initiation in potato plants infected with Verticillium spp

The growth pattern of potato plants, infected with V. albo-atrum and V. dahliae, was studied, using growth-analysis techniques, during the initial stages of development up to tuber initiation. During the first 5–6 weeks of growth the morphology of the infected plants was not affected, but the distribution of dry weight materials between various plant organs and the growth rates of the whole plants were affected much sooner. In contrast to healthy plants, those infected exhibited lower specific leaf areas, higher leaf weight ratios and higher leaf area ratios, and, under dry conditions, lower relative growth rates and lower unit leaf rates. Thus during the incubation phase of the disease, although effects of infection are not immediately apparent, Verticillium pathogens have a considerable influence upon the development of the host.     

Effect of main stem number and lateral stem development in potato plants infected with Verticillium albo-atrum and V. dahliae

‘Early-dying’ disease was examined in potato plants (King Edward) with varying numbers of main stems and lateral stems. Infection with Verticillium affected neither the number of main stems produced nor the stem number/ lateral number/yield inter-relationships, but did slightly reduce lateral development. The host growth pattern, however, markedly influenced the severity of disease: infected plants with a single main stem or a few, compared with those having many main stems, showed delayed symptom expression and also produced many laterals which further reduced disease severity and increased longevity. Thus yield reductions as a result of infection are likely to be smaller in single-stemmed plants showing considerable lateral development than in those plants with many main stems and few or no laterals.     

Molecular phylogeny and systematics of leaf‐mining flies (Diptera: Agromyzidae): delimitation of Phytomyza Fallén sensu lato and included species groups,with new insights on morphological and host‐use evolution

Abstract Phytomyza Fallén is the largest genus of leaf‐mining flies (Agromyzidae), with over 530 described species. Species of the superficially similar genus Chromatomyia Hardy have been included in Phytomyza by some authors and the status of the genus remains uncertain. Using 3076 bp of DNA sequence from three genes [cytochrome oxidase I (COI), CAD (rudimentary), phosphogluconate dehydrogenase (PGD)] and 113 exemplar species, we identified and tested the monophyly of host‐associated species groups in Phytomyza and Chromatomyia and investigated the phylogenetic relationships among these groups. Chromatomyia is polyphyletic and nested largely within Phytomyza; two small groups of species, however, are related more closely to Ptochomyza and Napomyza. Therefore, we synonymize Chromatomyia syn.n. , Ptochomyza syn.n. , and Napomyza syn.n. with Phytomyza, recognizing Ptochomyza, Napomyza and Phytomyza sensu stricto as subgenera of Phytomyza. We recognize five major clades within Phytomyza sensu stricto that comprise the majority of species ascribed previously to Chromatomyia and Phytomyza. Many species groups recognized previously were recovered as monophyletic, or virtually so, but some (e.g. robustella and atomaria groups) required emendation. On the basis of the proposed phylogeny and recent taxonomic literature, we present a preliminary revision of 24 species groups within Phytomyza, but leave many species unplaced. Evolution of internal pupariation (within the host’s tissue), regarded as a defining character of the former Chromatomyia, is discussed with regard to the new phylogeny, and we suggest a correlation with stem or leaf midrib mining. The large size of the Phytomyza lineage and an inferred pattern of host family‐specific species radiations make it a promising candidate for the study of macroevolutionary patterns of host shift and diversification in phytophagous insects. The proposed generic synonymies necessitate a number of new combinations. The following 46 species described in Chromatomyia are transferred to Phytomyza: P. actinidiae (Sasakawa) comb.n. , P. alopecuri (Griffiths) comb.n. , P. arctagrostidis (Griffiths) comb.n. , P. beigerae (Griffiths) comb.n. , P. blackstoniae (Spencer) comb.n. , P. centaurii (Spencer) comb.n. , P. chamaemetabola (Griffiths) comb.n. , P. cinnae (Griffiths) comb.n. , P. compta (Spencer) comb.n. , P. cygnicollina (Griffiths) comb.n. , P. doolittlei (Spencer) comb.n. , P. elgonensis (Spencer) comb.n. , P. eriodictyi (Spencer) comb.n. , P. flavida (Spencer) comb.n. , P. fricki (Griffiths) comb.n. , P. furcata (Griffiths) comb.n. , P. griffithsiana (Beiger) comb.n. , P. hoppiella (Spencer) comb.n. , P. ixeridopsis (Griffiths) comb.n. , P. kluanensis (Griffiths) comb.n. , P. leptargyreae (Griffiths) comb.n. , P. linnaeae (Griffiths) comb.n. , P. luzulivora (Spencer) comb.n. , P. mimuli (Spencer) comb.n. , P. mitchelli (Spencer) comb.n. , P. montella (Spencer) comb.n. , P. nigrilineata (Griffiths) comb.n. , P. nigrissima (Spencer) comb.n. , P. orbitella (Spencer) comb.n. , P. paraciliata (Godfray) comb.n. , P. poae (Griffiths) comb.n. , P. pseudomilii (Griffiths) comb.n. , P. qinghaiensis (Gu) comb.n. , P. rhaetica (Griffiths) comb.n. , P. scabiosella (Beiger) comb.n. , P. seneciophila (Spencer) comb.n. , P. shepherdiana (Griffiths) comb.n. , P. spenceriana (Griffiths) comb.n. , P. styriaca (Griffiths) comb.n. , P. subnigra (Spencer) comb.n. , P. suikazurae (Sasakawa) comb.n. , P. symphoricarpi (Griffiths) comb.n. , P. syngenesiae (Hardy) comb.n. , P. thermarum (Griffiths) comb.n. , P. torrentium (Griffiths) comb.n. and P. tschirnhausi (Griffiths) comb.n. Furthermore, we transfer all species of Napomyza to Phytomyza, resulting in the following new combinations: P. achilleanella (Tschirnhaus) comb.n. , P. acutiventris (Zlobin) comb.n. , P. angulata (Zlobin) comb.n. , P. arcticola (Spencer) comb.n. , P. bellidis (Griffiths) comb.n. , P. carotae (Spencer) comb.n. , P. cichorii (Spencer) comb.n. , P. curvipes (Zlobin) comb.n. , P. dubia (Zlobin) comb.n. , P. filipenduliphila (Zlobin) comb.n. , P. flavivertex (Zlobin) comb.n. , P. flavohumeralis (Zlobin) comb.n. , P. genualis (Zlobin) comb.n. , P. grandella (Spencer) comb.n. , P. humeralis (Zlobin) comb.n. , P. immanis (Spencer) comb.n. , P. immerita (Spencer) comb.n. , P. inquilina (Kock) comb.n. , P. kandybinae (Zlobin) comb.n. , P. lacustris (Zlobin) comb.n. , P. laterella (Zlobin) comb.n. , P. manni (Spencer) comb.n. , P. maritima (Tschirnhaus) comb.n. , P. merita (Zlobin) comb.n. , P. mimula (Spencer) comb.n. , P. minuta (Spencer) comb.n. , P. montanoides (Spencer) comb.n. , P. neglecta (Zlobin) comb.n. , P. nigriceps (van der Wulp) comb.n. , P. nugax (Spencer) comb.n. , P. pallens (Spencer) comb.n. , P. paratripolii (Chen & Wang) comb.n. , P. plumea (Spencer) comb.n. , P. plumigera (Zlobin) comb.n. , P. prima (Zlobin) comb.n. , P. pubescens (Zlobin) comb.n. , P. schusteri (Spencer) comb.n. , P. scrophulariae (Spencer) comb.n. , P. suda (Spencer) comb.n. , P. tanaitica (Zlobin) comb.n. , P. tenuifrons (Zlobin) comb.n. , P. vivida (Spencer) comb.n. , P. xizangensis (Chen & Wang) comb.n. and P. zimini (Zlobin) comb.n. Phytomyza asparagi (Hering) comb.n. and P. asparagivora (Spencer) comb.n. are transferred from Ptochomyza. In Phytomyza ten new names are proposed for secondary homonyms created by generic synonymy: P. echo Winkler nom.n. for P. manni Spencer, 1986; P. californiensis Winkler nom.n. for C. montana Spencer, 1981 ; P. griffithsella Winkler nom.n. for C. griffithsi Spencer, 1986; P. vockerothi Winkler nom.n. for C. nigrella Spencer, 1986; P. kerzhneri Winkler nom.n. for N. nigricoxa Zlobin, 1993; P. asteroides Winkler nom.n. for N. tripolii Spencer, 1966; P. minimoides Winkler nom.n. for N. minima Zlobin, 1994; P. nana Winkler nom.n. for N. minutissima Zlobin, 1994; P. ussuriensis Winkler nom.n. for N. mimica Zlobin, 1994 and P. zlobini Winkler nom.n. for N. hirta Zlobin, 1994.     

Effects of multi-year droughts on fish assemblages of seasonally drying Mediterranean streams

1. This study analysed changes occurring in Mediterranean stream fish assemblages over a sequence of dry years followed by a generally wet period (1991–98). Variations in assemblage attributes were quantified at the basin and stream reach scales, and related to variables reflecting the occurrence of unusually dry or wet conditions. 2. Assemblage variability increased along with the resolution of analysis, with little changes in species richness, composition and rank abundances, but significant variation in individual species abundances. Fluctuations in relative abundances were significantly affected by variables reflecting the severity of summer droughts and the occurrence of rainy springs. These patterns were evident at the basin scale, while variability at individual stream reaches tended to be higher and less related to rainfall patterns. 3. At least three response guilds to rainfall variation could be identified: two of the four abundant and widespread species (chub and loach) declined following dry years, whereas the two other core species (nase and eel) declined after rainy spring; one scarce native species (stickleback) increased in dry years. 4. Except at the two most upstream reaches, the assemblages tended to recover quickly to previous configuration after the changes occurring during the sequence of dry years. 5. Temporal variability of local assemblages was concordant among reaches but did not follow any consistent spatial pattern. Instead, spatial patterns in assemblage attributes changed over time in response to environmental variability, with a tendency for a disruption of upstream–downstream gradients following dry years. 6. Results supported the view that present‐day droughts cause relatively small and transient changes to Mediterranean stream fish assemblages. However, longer and more severe droughts expected under altered future climates, may result in declines or local extinctions of the most sensitive species and their potential replacement by more resistant species. Changing drought regimes thus need to be duly considered in the development of conservation strategies for Mediterranean stream fish.     

Cell Surface Carbohydrate Differences in Wild and Mutant Strains of Crithidia fasciculata1

Wild type Crithidia fasciculata and three drug-resistant mutant strains that have shown “flagellar adherence” were studied as to their ability to agglutinate with lectins specific for receptor molecules containing N-acetyl glucosamine, N-acetyl galactosamine, galactose, mannose-like residues, fucose, and sialic acid. Escherichia coli with mannose-sensitive fimbriae was also used as an agglutination probe. The presence of D-GalNAc, D-Gal, and mannose-like residues was detected in the wild strain. Generally, in the mutants, residues of these sugar units were present in greater concentrations when compared to the wild type strain. β-Galactosidase treatment showed that β-D-Galp units are exposed on the cell membrane. All types of cell agglutination including flagellum-flagellum (F-F), flagellum-soma (F-S), and soma-soma (S-S) were observed when lectins were used; however, with E. coli only the F-F type of cell agglutination was observed with the wild type strain and the TFR^R1 mutant. All types of agglutination were observed with the other two mutants.