Nucleotide and derived amino acid sequence of the cyanogenic β-glucosidase (linamarase) from white clover (Trifolium repens L.)

The nucleotide sequence and derived amino acid sequence of two different -glucosidase cDNA clones were determined. One clone (TRE104) was identified as the cyanogenic -glucosidase by homology with the N-terminal and internal peptide amino acid sequence of the purified enzyme. The biological function of the other -glycosidase (TRE361) is not known. Co-segregation of genomic restriction fragments uniquely identified by each cDNA clone shows that these two genes are linked in the white clover genome. Both TRE104 and TRE361 fragments co-segregate with cyanogenic -glucosidase activity. Extensive homology was found between the white clover -glucosidase sequences and a group of prokaryote and mammalian -glycosidases. This group of sequences has no homology with a separate set of -glucosidase genes isolated from fungi and the thermophilic bacterium Clostridium thermocellum.     

Changes in α- and β-amylase activities during seed germination of clover (Trifolium repens)

Changes in α- and β-amylase activities in the cotyledons of germinating clover were examined. The activity of α-amylase decreased during germination and growth of seedling, while β-amylase activity increased. These changes are different from those of germinating seeds of many other plants, but similar to the germinating seeds of alfalfa, which belongs to the same tribe (Trifolieae) as clover.     

Toxic events in the Northwest Pacific coastline of Mexico during 1992–1995: origin and impact

Previously considered as toxin-free, the Baja California Peninsula has witnessed several toxic algal blooms during the past three years. Apparently these ‘red-tide’ phenomena's outbreaks are not linked to any human related activity. This may just reflect better detection and training. Such events may be periodical and natural rather than induced. The most common types of marine toxins have been detected along the coast of the Peninsula and neighboring waters by mouse bioassay and chromatographic techniques. These are: Tetrodotoxin (TTX), Amnesic Shellfish Poison (ASP), Paralytic Shellfish Poisons (PSP), Diarrhetic Shellfish Poisons (DSP) and even Ciguatera (CFP), which are related to the presence of organisms of Prorocentrum sp. and Alexandrium sp. groups, and the diatom Pseudonitzschia sp. among others. There are also some indications about different kinds of TTX in the puffer fish of the region, and reasons to believe that we are facing a quite different pattern in toxic components, since PSP toxic potency (defined as the number of mouse units per gram(MU/g)of shellfish meat) is very high in spite of low dinoflagellates cell density registered. The ecological and social impact of the above has been considerable, with mass deaths of shellfish, seagulls, dolphins and turtles, and even some human casualties. The locally registered toxicity records: PSP found in one single fanshell reaches to 23 000 MU/100 g of tissue as determined by the mouse bioassay and, on a different event, two persons killed after ingesting puffer fish fillet. The largest reservoir of commercial marine organisms in Mexico is precisely the Northwest coast of the country and important plans for building large harbors and develop aquaculture areas are in progress. Therefore, a monitoring program is essential for an adequate management of such resources. Considering the large extension of the Peninsula (about1600 km)and, at this time, the lack of efficient communication means and scarce population, the implementation of such monitoring programs presents a big challenge. This revised version was published online in August 2006 with corrections to the Cover Date.     

Soil-borne seed pathogens: contributors to the naturalization gauntlet in Pacific Northwest (USA) forest and steppe communities?

Soil-borne seed pathogens are omnipresent but are often overlooked components of a community’s biotic resistance to plant naturalization and invasion. Using multi-year greenhouse experiments, we compared the seed mortality of single invasive, naturalized, and native grass species in sterilized and unsterilized soils collected from Pacific Northwest (USA) steppe and forest communities. Native Pseudoroegneria spicata displayed the greatest seed mortality, naturalized Secale cereale displayed intermediate seed mortality, and invasive Bromus tectorum was least affected by soil pathogens. Seed mortality across all three species was consistently greater in soils collected from steppe than soils collected from forest; seeds sown into sterilized steppe soil experienced half the overall seed mortality compared to seeds sown into unsterilized steppe soil. Soil sterilization did not affect grass seed mortality in forest soils. We conclude that (1) removing soil-borne pathogens with sterilization does increase native and non-native grass seed survival, and (2) soil-borne pathogens may influence whether an introduced species becomes invasive or naturalized within these Pacific Northwest communities as a result of differential seed survival. Soil-borne pathogens in these communities, however, have the greatest negative effect on the survival of native grass seeds, suggesting that the native microbial soil flora more effectively attack seeds of native plants than seeds of non-native species.     

Species distinction in the “Potentilla pollen type” (Rosaceae) of NW Europe

Pollen grains of eight different species from the genera Comarum, Fragaria, Potentilla and Sibbaldia, usually considered as one type, the “Potentilla type”, were examined and morphological features making distinction possible are described     

Modular construction of the protoderm and peripheral root cap in the “open” root apical meristem ofTrifolium repens cv. Ladino

Summary Roots with open apical organization are defined by not having specific tiers of initial cells in the root apical meristem; those with closed apical organization have specific initial tiers to which all cell files can be traced. An example of the clear organization of closed roots is the development protocol of the root cap and protoderm. The key event in differentiating these tissues is the T-division, a periclinal division of the root cap/protoderm (RCP) initial that establishes a module. Each module comprises two packets, the protoderm and peripheral root cap. Consecutive T-divisions of the same RCP initial produce up to five modules on average in a lineage of cells in white clover (Trifolium repens cv. Ladino), with all lineages around the circumference of the root dividing in waves to form one module prior to the next. On average, clover has approximately 32 axial protoderm and peripheral root cap cells in each module, and 32 RCP lineages. The occurrence of RCP T-divisions in white clover, a root with open apical organization, and the subsequent modular construction of the root cap and protoderm, provides a link between open and closed roots and suggests a common developmental feature that most roots of seed plants may share independent of their root meristem organization type. The open apical organization of the white clover root varies from roots with closed apical organization in that the RCP initials occur in staggered positions instead of connected to discrete tiers, and the peripheral root cap and columella daughter cells form additional layers of cells. White clover also forms root hairs on all protoderm cells irrespective of their position relative to the underlying cortical cells.Abbreviations RAM root apical meristem - RCP root cap protoderm - prc peripheral root cap     

Reemergence of Guadalupe fur seals in the U.S. Pacific Northwest: The epidemiology of stranding events during 2005–2016

Guadalupe fur seals (GFS), Arctocephalus philippii townsendi, an U.S. Endangered Species Act threatened pinniped, have recently reappeared in their historic range along the western seaboard of the continental United States. Starting 2005 through 2016, 169 GFSs stranded in Washington and Oregon, involving two designated unusual mortality events. The circumstances surrounding GFS strandings, mortality, and their increased presence in Oregon and Washington were analyzed during this study. Detailed necropsies, histopathology (n = 93), and epidemiological analysis found three main causes of death (COD): emaciation (44%), trauma (29%), and infectious disease (19%) and the factors associated with overall strandings and emaciation. Trauma included many cases found associated with fisheries interactions and clustered near the mouth of the Columbia River, where high levels of commercial fishing occur. The most common pathogens found associated with disease were Toxoplasma gondii, Sarcocystis neurona, and gastrointestinal helminths. Seasonality and upwelling were associated with higher stranding numbers regardless of COD. Seasonal migration into the region, coinciding with postweaning, suggests young GFSs are in search of prey and habitat resources. Reemergence of GFSs is likely due to conservation efforts, which have been critical for species recovery in the region. Continued monitoring is needed as this vulnerable species continues to rebound.     

Assessment of genotoxicity of herbal medicinal products: Application of the “bracketing and matrixing” concept using the example of Valerianae radix (valerian root)

An assessment of genotoxicity is a precondition for marketing authorization respectively registration of herbal medicinal products (HMPs), as well as for inclusion into the ‘Community list of herbal substances, preparations and combinations thereof for use in traditional herbal medicinal products’ established by the European Commission in accordance with Directive 2001/83/EC as amended, and based on proposals from the Committee on Herbal Medicinal Products (HMPC).In the ‘Guideline on the assessment of genotoxicity of herbal substances/preparations’ (EMEA/HMPC/107079/2007) HMPC has described a stepwise approach for genotoxicity testing, according to which the Ames test is a sufficient base for the assessment of genotoxicity in case of an unequivocally negative result. For reducing efforts for testing of individual herbal substances/preparations, HMPC has also developed the ‘guideline on selection of test materials for genotoxicity testing for traditional herbal medicinal products/herbal medicinal products’ (EMEA/HMPC/67644/2009) with the aim to allow testing of a standard range of test materials which could be considered representative of the commonly used preparations from a specific herbal drug according to a ‘bracketing/matrixing’ approach.The purpose of this paper is to provide data on the practical application of this bracketing and matrixing concept using the example of Valerianae radix, with the intention of facilitating its inclusion in the “Community list”. Five extraction solvents, representing the extremes of the polarity range and including also mid-range extraction solvents, were used, covering the entire spectrum of phytochemical constituents of Valerianae radix, thereby including polar and non-polar constituents. Extracts were tested in the Ames test according to all relevant guidelines. Results were unequivocally negative for all extracts. A review of the literature showed that this result is in accordance with the available data, thus demonstrating the lack of a genotoxic potential.In conclusion the two guidelines on genotoxicity provide a practically applicable concept. Valerianae radix has no genotoxic potential, supporting its use in HMPs and its inclusion in the Community list.     

Cell division patterns of the protoderm and root cap in the “closed” root apical meristem ofArabidopsis thaliana

Summary The peripheral root cap and protoderm inArabidopsis thaliana are organized into modular packets of cells derived from formative T-divisions of the root cap/protoderm (RCP) initials and subsequent proliferative divisions of their daughter cells. Each module consists of protoderm and peripheral root cap packets derived from the same periclinal T-division event of an RCP initial. Anatomical analyses are used to interpret the history of extensively coordinated cell divisions producing this modular construction. Within a given layer of root cap, the columella and RCP initials divided in a centrifugal sequence from the innermost columella initials toward the RCP initials. All RCP initials in the lineages around the circumference of the root divided nearly simultaneously in waves to form one module prior to the next wave of initial divisions forming a younger module. The peripheral root cap and protoderm packets within each module completed four rounds of proliferative divisions in the axial plane to produce, on average, 16 cells per packet in the basalmost modules in axial view. Peripheral root cap and protoderm cells predominantly in the T-type (trichoblast) lineages also underwent radial divisions as they were displaced basipetally. The regularity in the cellular pattern within the modules suggests a timing mechanism controlling highly coordinated cell division in the initials and their daughter cells.Abbreviations RAM root apical meristem - RCP root cap protoderm - prc peripheral root cap     

“Indians” and native Americans in the movies: A history of stereotypes,distortions, and displacements

Knowledge about Indian cultures and history among non‐native children is extremely limited and stereotyped due to a continued process of distortions and displacements in literature and particularly in Hollywood movies. The dual Indian stereotype was functionalized according to the colonizers’ interests. Hollywood movies depicted Indians first as noble or blood‐thirsty savages, then, in the fifties, as cyphers in melodramatic racial conflicts, and in the seventies, as heroes of an anti‐war counterculture. Recently, films showing Indians as believable individuals have emerged, and native American actors and filmmakers are ready to be heard and seen.     

Erwinia carotovora ssp.carotovora Infection Induced“Defense Lignin”Accumulation and Lignin Biosynthetic Gene Expression in Chinese Cabbage(Brassica rapa L.ssp.pekinensis)

Erwinia carotovora subsp. carotovora (Ecc) infects and causes soft rot disease in hundreds of crop species includingvegetables, flowers and fruits. Lignin biosynthesis has been implicated in defensive reactions to injury and pathogeninfection in plants. In this work, variations of lignin content and gene expression in the molecular interaction betweenChinese cabbage and Ecc were investigated. H_2O_2 accumulation and peroxidase activity were detected by 3, 3-Dimethoxybenzidine staining at mocked and Ecc-inoculated sites of Chinese cabbage leafstalks. Mason lignin contentin inoculated plants increased by about 7.84%, 40.37%, and 43.13% more than that of the mocked site at 12, 24 and 72 hafter inoculation, respectively. Gas chromatography detected more p-coumaryl (H) and less coniferyl (G) and sinapyl (S)monolignins in leafstalks of Chinese cabbage. All three monomers increased in Ecc-infected leafstalks, and the Ecc-induced"defense lignin" were composed of more G and H monolignins, and less S monolignin. After searching the expressedsequence tags (EST) data of Chinese cabbage, 12 genes putatively encoding enzymes involved in lignin biosynthesis wereselected to study their expression. All of these genes could be induced by mock inoculation and Ecc infection, while thegene expression lasted for several more hours in the infected samples than in mocked and untreated plants. Our resultsindicated that "defense lignin" was different from the developmental lignin in composition; G and S monolignins weresignificantly induced in plants in response to the soft rot Ecc; thus, lignin biosynthesis was differentially regulated andplayed a role in plant response to the soft rot Ecc.     

Assessment of the efficiency of different control programs to reduce Trioza apicalis Först. (Triozidae: Hemiptera) feeding damage and the spread of “Candidatus Liberibacter solanacearum” on carrots (Daucus carota ssp. sativus L.)

The control of carrot psyllid Trioza apicalis Förster largely relies on chemical measures, and the current integrated pest management (IPM) strategy is based on pest scouting. The number of active ingredients available for psyllid control will further decline in the coming years. The need for alternative control measures is therefore urgent. In this work the efficiency of different control programs including a kaolin particle film and plant-derived, crude saponin extract, chemical control, insect net and IPM (kaolin in combination with insecticides) programs to reduce psyllid feeding damage, reproduction and the spread of “Candidatus Liberibacter solanacearum” (CLso) in carrots was studied. Each year in 2016–2018, four replicates of each treatment were randomised in a row-column design on a commercial carrot farm. After the treatments were executed, the psyllid nymphs and eggs were counted. At the harvest, the carrot roots and shoots were weighed, damages assessed, and samples were taken for CLso detection from 50 plants at each replicate. Kaolin treatment alone and in combination with insecticides effectively reduced the number of psyllid nymphs and eggs in all the years studied. Saponin was applied only on the first year, since it significantly increased the number of T. apicalis eggs compared to other treatments. The insect net was superior to other treatments in all the studied aspects in all the years. Under normal weather conditions, the highest root weight was harvested under the insect net, followed by the chemical control program consisting of pyrethroids, kaolin treatment, untreated control and saponin treatment. During extreme weather conditions, chemical control programs were not effective at protecting the carrots from psyllid feeding, which was reflected as low root yield. In all years, the carrot leaf damage percent negatively correlated with the root weight. Similarly, the shoot:root ratio increased as the leaf-curling percentage rose, which was even pronounced under drought stress. The effect of climatic stress should be considered when developing IPM strategies.     

Cloning and sequence analysis of the X-Prolyl-dipeptidyl-aminopeptidase gene (pepX) from Lactobacillus delbrückii ssp. lactis DSM7290

Lactobacillus delbrückii ssp. lactis DSM7290 possesses an X-prolyl-dipeptidyl-aminopeptidase, designated PepX, which catalyses the hydrolytic removal of N-terminal dipeptidyl residues from peptides containing proline in the penultimate position. Using the specific substrate L-Ala-L-Pro-p-nitroanilide, PepX was purified by a four-step procedure including ammonium sulphate fractionation, hydrophobic interaction chromotography, ion exchange chromotography, and affinity chromotography. The N-terminus of the purified protein was sequenced. Screening of a gene library of chromosomal Lactobacillus delbrückii ssp. lactis DSM7290 DNA in the low-copy-number vector pLG339 resulted in the identification of the pepX gene in Escherichia coli using a specific plate assay with Gly-L-Pro--naphthalamide as substrate. Nucleotide sequence analysis revealed an open reading frame of 2376 bp, coding for a protein of 792 amino acids with a molecular mass of 88449 Da. Correspondence to: E. C. Meyer-Barton     

Emergence,Development, and Maturity of the Gonad of Two Species of Chitons “Sea Cockroach” (Mollusca: Polyplacophora) through the Early Life Stages

This study describes and recognises, using histological and microscopical examinations on a morphometrical basis, several gonad traits through the early life stages of Chiton articulatus and C. albolineatus. Gonadal ontogenesis, gonad development stages, sexual differentiation, onset of the first sexual maturity, and growth sequences or “early life stages” were determined. In addition, allometry between lengths and body weight pooled for both sexes per each chiton were calculated using equation Y = aX^b. A total of 125 chitons (4≤TL≤40 mm, in total length “TL”) were used. All allometric relations showed a strong positive correlation (r), close to 1, with b-values above three, indicating an isometric growth. Gonadal ontogenesis and gonad development stages were categorised into three periods (“Pw” without gonad, “Pe” gonad emergence, and “Pf” gonadal sac formed) and four stages (“S0” gametocytogenesis, “S1” gametogenesis, “S2” mature, and “S3” spawning), respectively. Compound digital images were attained for each process. Periods and stages are overlapped among them and between species, with the following overall confidence intervals in TL: Pw 6.13–14.32 mm, Pe 10.32–16.93 mm, Pf 12.99–25.01 mm, S0 16.08–24.34 mm (females) and 19.51–26.60 mm (males), S1 27.15–35.63 mm (females) and 23.45–32.27 mm (males), S2 24.48–40.24 mm (females) and 25.45–32.87 mm (males). Sexual differentiation (in S0) of both chitons occurs first as a female then as a male; although, males reach the onset of the first sexual maturity earlier than females, thus for C. articulatus males at 17 mm and females at 32 mm, and for C. albolineatus males at 23.5 mm and females at 28 mm, all in TL. Four early life stages (i.e., subjuvenile, juvenile, subadult, and adult) are described and proposed to distinguish growth sequences. Our results may be useful to diverse disciplines, from developmental biology to fisheries management.     

Two Genes (ClS1 and ClF-box) Involved the Self-Incompatibility of ”Xiangshui” Lemon (Citrus limon (L.) Burm. f.)

Plant Molecular Biology Reporter - Gametophytic self-incompatibility (GSI) is an important factor affecting fruit development and is one of the important mechanisms of seedlessness in citrus....