CONTRIBUTION OF POLLEN MORPHOLOGY TO SYSTEMATICS OF COLLOMIA (POLEMONIACEAE)

Pollen morphology of 14 species of Collomia (Polemoniaceae) was examined by light microscopy, and by both scanning and transmission electron microscopy. Four distinct pollen types were observed which are based principally upon 1) shape, number and distribution of apertures, and 2) surface sculpturing: Type 1—zonocolporate with striate ridges; Type 2—zonocolporate with striato-reticulate ridges; Type 3—pantoporate with radiate ridges; Type 4—pantoporate with irregularly reticulate ridges. Evaluation of pollen morphology reveals considerable discrepancy with respect to presently accepted sectional classification. Collomia grandiflora of sect. Collomia has a pollen type similar to that of members of sect. Collomiastrum and is now interpreted as representing an independent evolutionary line derived from the latter section. Collomia diversifolia of sect. Courtoisia has a pollen morphology similar to that of sect. Collomia. whereas C. heterophylla of the same section possesses pollen unique within the genus. This last pollen type shows close similarity to the pollen of members of Polemonium, Gilia, Leptodactylon, and Ipomopsis. Pollen of C. tinctoria and C. tracyi of sect. Collomia are anomalous within Polemoniaceae. No significant difference in exine stratification was discernible among the four pollen types.     

FLEXURAL STIFFNESS ALLOMETRIES OF ANGIOSPERM AND FERN PETIOLES AND RACHISES: EVIDENCE FOR BIOMECHANICAL CONVERGENCE

Evidence for convergence in biomechanical and anatomical features of leaves (elastic modulus E, second moment of area I, taper of petioles, the longitudinal distribution of petiolar and laminar weight, and volumes of tissues) is presented based on a survey of 22 species (distributed among dicots, monocots, and ferns). In general, regardless of taxonomic affinity, petioles were found to be mechanically constructed in one of two ways: Type I petioles—as cantilevered, end-loaded beams with relatively uniform flexural stiffness (EI) (simple and palmate leaves); and Type II petioles—as tapered cantilevered beams whose static loadings (biomass) and EI increase basipetally (pinnate leaves). In general, collenchyma and sclerenchyma were found to be peripherally located in transections through Type I and II petioles, respectively. Statistical analyses within each species and among species with either type of petiole indicated that EI ≈ k₁Lp^2.98 and EI ≈ k₂Lp^2.05 for Type I and II petioles, respectively, where k₁ and k₂ are dimensional constants and Lp is petiolar length. The data are interpreted to indicate that Type I and II petioles mechanically operate to deal with static loadings in two distinct ways, such that Type II petioles function in an analogous manner to branches supporting separate leaves (leaflets). The convergence in mechanical “designs” among taxonomically distinct lineages (angiosperms and ferns) is interpreted as evidence for selection on mechanical attributes of load supporting structures (petioles).     

SEED-COAT MORPHOLOGY AND ANATOMY IN COLLOMIA (POLEMONIACEAE)

Seed-coat morphology of 14 species of Collomia (Polemoniaceae) was examined with light microscopy and scanning electron microscopy. Two seed types were observed based on surface sulpturing: Type 1—hexagonal epidermal cells forming a shallow reticulum with well-defined cell boundaries; Type 2—longitudinally ridged and irregularly arranged crater-like depressions with inconspicuous cell boundaries. Only two species, C. debilis and C. larsenii of sect. Collomiastrum have seed-coat Type 1. Seed-coat Type 2 is characteristic of all species of sect. Collomia, sect. Courtoisia, and C. mazama, C. rawsoniana of sect. Collomiastrum. The present investigation reveals a fairly homogeneous seed-coat pattern in the genus and does not offer significant information for realignment of infrageneric classification. Anatomical studies with light microscopy show that a mucilaginous seed coat develops from the outermost layer of integument in which each epidermal cell develops spiral secondary wall thickenings. Mucilaginous seeds of most Collomia species probably provide adaptive significance in that adherence of seeds to ground prohibits further dispersal to unfavorable habitats, or epizoochoric dispersal.     

Modification of the PthA4 effector binding elements in Type I CsLOB1 promoter using Cas9/sgRNA to produce transgenic Duncan grapefruit alleviating XccΔpthA4:dCsLOB1.3 infection

Citrus canker caused by Xanthomonas citri subspecies citri (Xcc) is a severe disease for most commercial citrus cultivars and responsible for significant economic losses worldwide. Generating canker‐resistant citrus varieties will provide an efficient and sustainable solution to control citrus canker. Here, we report our progress in generating canker‐resistant grapefruit by modifying the PthA4 effector binding elements (EBEs) in the CsLOB1 Promoter (EBE_PthA4‐CsLOBP) of the CsLOB1 (Citrus sinensis Lateral Organ Boundaries) gene. CsLOB1 is a susceptibility gene for citrus canker and is induced by the pathogenicity factor PthA4, which binds to the EBE_PthA4‐CsLOBP to induce CsLOB1 gene expression. There are two alleles, Type I and Type II, of CsLOB1 in Duncan grapefruit. Here, a binary vector was designed to disrupt the PthA4 EBEs in Type I CsLOB1 Promoter (TI CsLOBP) via epicotyl transformation of Duncan grapefruit. Four transgenic Duncan plants with targeted modification of EBE_PthA4‐T1 CsLOBP were successfully created. As for Type I CsLOB1 promoter, the mutation rate was 15.63% (#D13), 14.29% (#D17), 54.54% (#D18) and 81.25% (#D22). In the presence of wild‐type Xcc, transgenic Duncan grapefruit developed canker symptoms similarly as wild type. An artificially designed dTALE dCsLOB1.3, which specifically recognizes Type I CsLOBP, but not the mutated Type I CsLOBP or Type II CsLOBP, was developed to infect Duncan transformants. Consequently, #D18 had weakened canker symptoms and #D22 had no visible canker symptoms in the presence of XccΔpthA4:dCsLOB1.3. Our data suggest that activation of a single allele of susceptibility gene CsLOB1 by PthA4 is sufficient to induce citrus canker disease, and mutation in the promoters of both alleles of CsLOB1 is probably required to generate citrus canker‐resistant plants. This work lays the groundwork to generate canker‐resistant citrus varieties via Cas9/sgRNA in the future.     

REGENERATION RESPONSES IN PEA ROOTS AFTER TIP EXCISION AT DIFFERENT LEVELS

Root tips of Pisum sativum cv Alaska were excised at seven excision distances ranging from 250 to 5,000 μm from the root cap/body junction. Three response types resulted: 1) Type A— One to three regenerated apices grew in the same plane as the root axis; 2) Type B—One to three regenerates emerged either longitudinally from a swollen wound site or at angles >90“° from the root longitudinal axis; 3) Type C—One to three lateral roots emerged at 90° from the root axis. The response type was dependent on the excision distance: Type A response resulted after excisions of 250 and 500 μm, Type B after excisions of 1,000 and 1,500 μm, and Type C after excisions of > 1,500 μm. The vascular patterns of the regenerated roots varied with excision distance. Most regenerates resulting after being excised at 250 μm exhibited variations in xylem strand number. Most of those resulting after being excised at 500 μm were ”polystelic“ and few of these showed variation in xylem strand number. With increasing excision distance the number of regenerates with variation in xylem stand number or with a ”polystelic“ condition decreased. Both the type of regeneration response and the vascular patterns within the regenerates correlated with the state of differentiation of cells at each excision distance.     

Effect of Weak Sinusoidal Magnetic Field on Germination and Yield of Cotton (Gossypium spp.)

This paper presents the results of a preliminary study on the effects of sinusoidal magnetic fields on percentage germination, growth, and yield of cotton (Gossypium species). The paper covers a brief account of the experimental setup, protocol, and the essential parameters employed. The study was carried out using var.spch‐1 cotton seeds having three different germination capacities (Type 1—31%, Type 2—49%, Type 3—64%). The seeds were subjected to magnetic fields with nine different frequencies and intensities as follows: A. 1 Hz, 100 nT; B. 1 Hz, 1500 nT; C. 1 Hz, 4000 nT; D. 10 Hz, 100 nT; E. 10 Hz, 1500 nT; F. 10 Hz, 4000 nT; G. 100 Hz, 100 nT; H. 100 Hz, 1500 nT; I. 100 Hz, 4000 nT. In Type 3 cotton seeds exposed to 10 Hz, 100 nT fields, the yield was 75.3% higher than that of control, and in Type 2 cotton seeds exposed to 100 Hz, 1500 nT fields, the yield was 85.2% higher than that of control.

The experiment leads to two major clear‐cut findings:

1. Pre‐sowing exposure of seeds to extremely low frequency (ELF) magnetic fields catalyzes certain varieties of cotton to yield as much as double the crop output yielded by unexposed controls.

2. The yield is strongly frequency dependent, i.e., the cotton varieties show outstanding responses only at specific frequencies.

     

Crystalloid Inclusions in Species of Leucocytozoon,Parahaemoproteus, and Plasmodium*†

Cytoplasmic vacuoles seen in methanol-fixed, Giemsa's-stained ookinetes of Leucocytozoon simondi, Parahaemoproteus fringillae and Plasmodium gallinaceum, when studied with the electron microscope, were found to correspond with crystalloid inclusions of similar structure, particle size, and arrangement. Cytochemical examination of these “crystalloids” revealed their lipid-protein nature. Morphologically similar inclusions were found also in ookinetes of Leucocytozoon ziemanni and Parahaemoproteus velans. In L. simondi, crystalloid is formed rapidly after fertilization, from amorphous electron dense material seen in mature macrogametocytes. The arrangement and distribution of crystalloids in the zygote, ookinete, oocyst, and sporozoite are described. On the basis of differences in structure and particle size, it is proposed that the crystalloid inclusions in Haemosporina be divided into 2 types. Type I—lipid-protein in nature, characterized by electron dense irregularly spherical particles, 25–40 nm in diameter, with individual particles not invested by membrane. Type II—probably virus, characterized by electron dense, irregularly spherical, membrane-bounded particles, with a diameter usually greater than 40 nm.     

Genetic relationship between tetraploids and pentaploids in the agamospermous species Taraxacum albidum Dahlst., clarified by enzyme electrophoresis

In order to reveal the genetic relationship of tetraploids and pentaploids in the agamospermous species Taraxacum albidum Dahlst., an allozyme study was carried out. Approximately 200 plants putatively identified as T. albidum were collected mainly from the Kyushu Island of Japan, and analyzed by enzyme electrophoresis. Two multilocus genotypes at 14 presumptive loci of nine enzymes, Type A and Type B, were detected. Most of the sample plants showed uniclonal Type A, which corresponds to “T. albidum” as reported in our previous paper. Type B, which is also uniclonal, was found at fewer localities and was clearly different from Type A in the allele composition of pgi-2 and pgm-1, as well as in the allele dosage at mdh and sod-1. By means of flow cytometry and chromosome count, the ploidy levels of Type A and Type B were shown to be pentaploid and tetraploid, respectively. A comparison of the allele composition suggests a hybrid origin of pentaploid T. albidum (Type A) from an unreduced gamete of Type B and a reduced gamete of any diploid Taraxacum species.     

Redesigning the type II' β‐turn in green fluorescent protein to type I': Implications for folding kinetics and stability

Both Type I' and Type II' β‐turns have the same sense of the β‐turn twist that is compatible with the β‐sheet twist. They occur predominantly in two residue β‐hairpins, but the occurrence of Type I' β‐turns is two times higher than Type II' β‐turns. This suggests that Type I' β‐turns may be more stable than Type II' β‐turns, and Type I' β‐turn sequence and structure can be more favorable for protein folding than Type II' β‐turns. Here, we redesigned the native Type II' β‐turn in GFP to Type I' β‐turn, and investigated its effect on protein folding and stability. The Type I' β‐turns were designed based on the statistical analysis of residues in natural Type I' β‐turns. The substitution of the native “GD” sequence of i+1 and i+2 residues with Type I' preferred “(N/D)G” sequence motif increased the folding rate by 50% and slightly improved the thermodynamic stability. Despite the enhancement of in vitro refolding kinetics and stability of the redesigned mutants, they showed poor soluble expression level compared to wild type. To overcome this problem, i and i + 3 residues of the designed Type I' β‐turn were further engineered. The mutation of Thr to Lys at i + 3 could restore the in vivo soluble expression of the Type I' mutant. This study indicates that Type II' β‐turns in natural β‐hairpins can be further optimized by converting the sequence to Type I'. Proteins 2014; 82:2812–2822. © 2014 Wiley Periodicals, Inc.     

Microreview: Innate immune encounters of the (Type) 4th kind: Brucella

In humans, pathogenic Brucella species cause a febrile illness known as brucellosis. A key pathogenic trait of this group of organisms is their ability to survive in immune cells and persist in tissues of the reticuloendothelial system, a process that requires the function of a Type IV secretion system. In contrast to other well‐studied Gram‐negative bacteria, Brucella spp. do not cause inflammation at the site of invasion, but have a latency period of 2–4 weeks before the onset of symptoms. This review discusses several mechanisms that allow Brucella spp. both to evade detection by pattern recognition receptors of the innate immune system and suppress their signalling. In contrast to these stealth features, the VirB Type IV secretion system, which mediates survival within phagocytic cells, stimulates innate immune responses in vivo. The responses stimulated by this virulence factor are sufficient to check bacterial growth, but not to elicit sterilizing immunity. The result is a stand‐off between host and pathogen that results in persistent infection.     

Osservazioni carioembriologiche in Ornithogalum di Sardegna: Nota I. - Sporogenesi e sviluppo dei gametofiti in Ornithogalum caudatum Ait

Abstract

CARYOEMBRYOLOGICAL STUDIES in ORNITHOGALUM OF SARDINIA.

I. - SPOROGENESIS AND DEVELOPMENT OF THE GAMETOPHYTES IN ÒRNITHOGALUM CAUDATUM AIT. — After a concise synthesis of the caryoembryological knowledges regarding the taxa of Ornithogalum present in Sardinia, the embryology and morphology of Ornithogalum caudatum Ait., have been investigated.

In a three-locular ovary the ovules are anatropous, epitropous with nucellus crassinucellate and only one archesporial cell evolves a mother cell.

The development of the female gametophyte tallies with the Polygonum (Normal) Type.

The homoetypical division presents an asynchronous proceeding in the cellules of the dyad with a considerable delay in the two-nucleate arrangement, especially in the chalazal cell.

Antipodal cells present a hypertrophic growing, but they present no tendency to polyantipody.

The endosperm is of the Helobiae Type.

The divisions of the pollen mother-cells are of the successive Type.

Longest axis of 1-sulcate pollen grains about 76 micron.

A true tapetal periplasmodium isn't formed in the anthers.

The chromosome number is 2n = 54.

Raphides accour in the cataphylls, in the parenchymatous tissues of the leaf and in several parts of the floral region.     

Molecular characterization of larval anisakid nematodes from marine fishes off the Moroccan and Mauritanian coasts

A total of 242 larval forms of Anisakis collected from marine fishes at different sites off the Moroccan and Mauritanian coasts, recognised as belonging to Type I and Type II larvae, were identified by PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphisms) of the ITS (Internal Transcribed Spacers) region (ITS-1, 5.8 subunit rRNA gene and ITS-2), using a previously established molecular key. The Type I larvae were found with a frequency of 98.34% and were identified as belonging to the following species: A. simplex s.str., A. pegreffii, A. simplex s.str/A. pegreffii heterozygote genotypes, A. typica, A. ziphidarum and Anisakis sp. A. The Type II larvae were found to belong to A. physeteris, with the frequency of 1.65%. The results reported in the present study provide further epizootiological and biological data on the Anisakis spp. in marine fishes off the Moroccan and Mauritanian coasts, improving the picture of the occurrence of these species in the central Atlantic coasts.     

Morphology of the petal inAconitum

The petals ofAconitum were classified into six types. Type I: the labium tubular at the base and no appendage inside. Type II: a lambda (A)-shaped enation present inside the limb. The upper part of the enation is situated at the lower edge of the spur mouth and both wings of the enation extend to margins of the labium. Type III resembles type II but both wings do not extend to the margins. Type IV: a small flap attached at the lower edge of the spur mouth. Type V: two auriculate appendages present on both lateral walls of the labium. Type VI: without inside appendage. Most species of sect.Lycoctonum have type I petal and those of sect.Aconitum have type V petal. Type I is distinctly cup-shaped or peltate with a well developed cross zone or adaxial wall and type II is a modification of type I. Type VI is distinctly flat or epeltate without the cross zone. Others are intermediate between cup-shaped and flat or peltate and epeltate types. Based on the observation of petal ontogeny onA. pterocaule var.glabrescens, A. vulparia andA. japonicum var.eizanense, the relation among these types was explained by the partial or total reduction of the adaxial meristematic regions.     

Selection of Type I and Type II methanotrophic proteobacteria in a fluidized bed reactor under non-sterile conditions

Type II methanotrophs produce polyhydroxybutyrate (PHB), while Type I methanotrophs do not. A laboratory-scale fluidized bed reactor was initially inoculated with a Type II Methylocystis-like dominated culture. At elevated levels of dissolved oxygen (DO, 9 mg/L), pH of 6.2–6.5 with nitrate as the N-source, a Methylobacter-like Type I methanotroph became dominant within the biofilms which did not produce PHB. A shift to biofilms capable of PHB production was achieved by re-inoculating with Type II Methylosinus culture, providing dissolved N₂ as the N-source, and maintaining a low influent DO (2.0 mg/L). The resulting biofilms contained both Types I and II methanotrophs. Batch tests indicated that biofilm samples grown with N₂ became dominated by Type II methanotrophs and produced PHB. Enrichments with nitrate or ammonium were dominated by Type I methanotrophs without PHB production capability. The key selection factors favoring Type II were N₂ as N-source and low DO.     

Insight into Types I and II nonhost resistance using expression patterns of defense-related genes in tobacco

Plants protect themselves against pathogens using a range of response mechanisms. There are two categories of nonhost resistance: Type I, which does not result in visible cell death; and Type II, which entails localized programmed cell death (or hypersensitive response) in response to nonhost pathogens. The genes responsible for these two systems have not yet been intensively investigated at the molecular level. Using tobacco plants (Nicotiana tabacum), we compared expression of 12 defense-related genes between a Type I (Xanthomonas axonopodis pv. glycines 8ra) nonhost interaction, and two Type II (Pseudomonas syringae pv. syringae 61 and P. syringae pv. phaseolicola NPS3121) nonhost interactions, as well as those expressed during R gene-mediated resistance to Tobacco mosaic virus. In general, expression of most defense-related genes during R gene-mediated resistance was activated 48 h after challenge by TMV; the same genes were upregulated as early as 9 h after infiltration by nonhost pathogens. Surprisingly, X. axonopodis pv. glycines (Type I) elicited the same set of defense-related genes as did two pathovars of P. syringae, despite the absence of visible cell death. In two examples of Type II nonhost interactions, P. syringae pv. phaseolicola NPS3121 produced an expression profile more closely resembling that of X. axonopodis pv. glycines 8ra, than that of P. syringae pv. syringae 61. These results suggest that Type I nonhost resistance may act as a mechanism providing a more specific and active defense response against a broad range of potential pathogens.     

Wissadula Proliferation in Jamaica II. Psyllid transmission and antibiotic therapy

Field symptoms of Wissadula proliferation (WP) in Jamaica were reproduced on W. periplocifolia (L.) C. Presl. ex Thwaites test plants, using field-collected or laboratory reared and infected Paracarsidara concolor Crawford. This psyllid naturally is associated with W. periplocifolia in the field. Diseased plants contained phloem-restricted prokaryotes, most of which resembled the phloem-restricted rickettsialike organisms (RLO) known to be associated with a small group of plant diseases. They were bound by a “cell wall” composed of a double unit membrane separated by an electron-lucent layer. A small proportion of the prokaryotes, which were bound by only one recognizable unit membrane and were ill-defined at the periphery, were difficult to distinguish from mycoplasmalike organisms (MLO). Penicillin, applied as a soil drench of 200—400 %mUg/ml caused remission of symptoms of the psyllid-infected test plants 6—17 days after first effective application, with the concomitant disappearance of all of the structures in the resulting new growth. Since MLO are not known to be penicillin-sensitive, it is proposed that the “MLO” were in fact, poorly preserved RLO and it is suggested that RLO may be the aetiological agent of WP. Achromycin also caused symptom remission in WP at a soil drench of 100—400 %mUg/ml, but was generally slightly slower-acting than penicillin, eliciting a response in 12—23 days. Both antibiotics could produce lengthy remissions; neither seemed curative since two penicillin- and two achromycin-treated plants redeveloped symptoms after cessation of treatment. WP was not transmitted by two cicadellids, Protalebra maculata Baker and Scaphytopius fuliginosus Osborn. P. concolor did not transmit disease to test plants of Abutilon hulseanum (Torr. & A. Gray) Torr, ex. Chapm. which was affected by a proliferation disease (Abutilon proliferation), symptomatologically similar to, and which occurred in the same locations, as WP. WP and AP thus may be aetiologically distinct. The putative RLO aetiology of WP provides evidence against Wissadula being an alternate host of the MLO-associated coconut lethal yellowing (CLY) disease in Jamaica, a fact reinforced by negative psyllid transmission tests to CLY-susceptible palms. The results for WP are discussed in relation to other diseases possibly caused by phloem-restricted RLO.     

Epidemiological study on the relationship between toxin production and psm-mec mutations in MRSA isolates in Thailand

In this present study, we investigated the phenol-soluble modulin (psm-mec) mutations, the staphylococcal cassette chromosome mec (SCCmec) types, and toxin production in 102 methicillin-resistant Staphylococcus aureus (MRSA) isolates from the northeast and central regions of Thailand. The MRSA isolates carrying -7T>C psm-mec in Type II SCCmec (n = 18) and the MRSA isolates carrying no psm-mec in Type IV (n = 8) or Type IX SCCmec (n = 4) had higher hemolytic activity against sheep erythrocytes than MRSA isolates carrying intact psm-mec in Type III SCCmec (n = 34), but MRSA isolates carrying no psm-mec in Type I SCCmec (n = 27) did not.     

Optimizing α for better statistical decisions: A case study involving the pace‐of‐life syndrome hypothesis

Setting optimal significance levels that minimize Type I and Type II errors allows for more transparent and well‐considered statistical decision making compared to the traditional α = 0.05 significance level. We use the optimal α approach to re‐assess conclusions reached by three recently published tests of the pace‐of‐life syndrome hypothesis, which attempts to unify occurrences of different physiological, behavioral, and life history characteristics under one theory, over different scales of biological organization. While some of the conclusions reached using optimal α were consistent to those previously reported using the traditional α = 0.05 threshold, opposing conclusions were also frequently reached. The optimal α approach reduced probabilities of Type I and Type II errors, and ensured statistical significance was associated with biological relevance. Biologists should seriously consider their choice of α when conducting null hypothesis significance tests, as there are serious disadvantages with consistent reliance on the traditional but arbitrary α = 0.05 significance level.     

Interactions between elicitins and radish Raphanus sativus

Two responses to elicitins are described in cultivars of radish (Raphanus sativus L.). Type I, exhibited by the cultivar Daikon, is characterised by wilting and desiccation within 24 h of elicitin application and was previously reported as the sensitive response (S. Kamoun et al. 1993, Mol Plant-Microbe Interact 6: 15–25). At 1 μg elicitin · g⁻¹ FW radish tissue, symptoms appeared after 8 h, a sensitivity comparable to that shown by tobacco to β elicitins (J.-C. Pernollet et al., 1993, Physiol Mol Plant Pathol 42: 53–67; S. Kamoun et al., 1993, Mol Plant-Microbe Interact 6: 15–25). Elicitin failed to induce these symptoms in the cultivar White Icicle, even at 100 μg · g⁻¹ FW of tissue. However, a different response (Type II) with symptoms resembling senescence appeared in White Icicle after 48 h and were fully developed by 72 h. The Type II response was induced at levels of elicitin above 0.3 μg · g⁻¹ FW. Elicitin-treated Daikon leaves held at 100% relative humidity, rather than ambient (50–60%) did not wilt and by 72 h displayed Type II symptoms. When treated Daikon leaves were removed to ambient humidity at any time during the latent period, they developed Type I symptoms within 2 h. Although Type I symptoms were suppressed in Daikon at high humidity, there was no indication that leaf diffusion resistance or plant water conductance were affected. Protoplasts from the cultivar Daikon responded to elicitin by H⁺ uptake and K⁺ release, with maximal response at 300 pM. The response was eliminated by K252a or staurosporine. Daikon protoplasts also showed transient uptake/secretion of Ca²⁺ on elicitin addition. Protoplasts from White Icicle gave neither of these responses. Both Daikon and White Icicle phenotypes could be transferred to progeny of Daikon-White Icicle crosses and in the F2 generation three phenotypes, including a null, segregated. Only those F2 plants which exhibited the Daikon phenotype produced protoplasts which responded to elicitin. Received: 13 May 1997 / Accepted: 27 August 1997     

Partial purification of Drosophila glutamate decarboxylase.

Abstract— A 600-fold purification of l -glutamatc decarboxylasc from Drosophila melanogaster Oregon R Wild Type has been achieved. The purification procedures involve the initial homogenization of whole flies in dilute potassium phosphate buffer containing dithiothreitol and phenylmethyl sulfonyl fluoride as protectors, followed by a series of column chromatography with hydroxylapatite, Sephadex G-150 and DEAE-Sephadex. The purified enzyme has an apparent K_m of 11 mm for l -glutamate and requires a 40mm -K⁺ for maximum activity. The purified enzyme shows only 1 pH optimum around pH 7.5, while crude preparations of the inset display 2 pH optima, pH 4.8–5.2. and 7.5. The significance and possible application of this study are also discussed.