Mature Heads Research Articles

Characterization of Early Maturing F1 Hybrid Varieties in Cabbage (Brassica oleracea L.)

A cabbage plant forms a mature head during the continuous process of vegetative growth, suggesting that head formation is affected by developmental characteristics before harvesting. We investigated characteristics of early maturing F1 hybrid varieties using 27 F1 hybrids composed of 21 F1 hybrids of mixed reciprocal combinations of 42 diallel crosses of 7 inbred lines and 6 commercial F1 hybrids. We estimated the number of days it took for the head to attain the target weight from transplantation (head-maturing period, HMP). The HMP to reach 1250 g (HMP1250), the most marketable weight in Japan, varied from 60 to 88 days among the materials and corresponded to their estimates based on grower’s experience. We thus considered that the HMP1250 was a valid measure of cabbage maturity. Correlation analysis between HMP1250 and developmental characteristics clarified that HMP1250 was correlated with the leaf shape index (width/length) of wrapper leaves, the leaf position at which head formation started and the size of wrapper leaves. This result suggested that cabbage maturity could be divided into those developmental characteristics. That is to say, early maturing F1 hybrid varieties had the following developmental characteristics; change to a large leaf shape index from the low leaf position, low leaf position at which their head formation started and large leaf size.

Lines of lettuce selected for ethylene insensitivity at the seedling stage displayed variable responses to ethylene or wounding as mature heads

Hypocotyl elongation in germinating lettuce (Lactuca sativa L., cv. Diana) M2 seedlings from an ethyl methanesulfonate treated population was used to select lines that were less sensitive to ethylene (C2H4) than the progenitor line. Individuals were identified that had hypocotyls at least twice as long in the presence of hormonal C2H4 levels (� /1 m ll 1 ) as wild-type plants. This phenotype was confirmed in M3 seedlings for three independent mutants. The phenotype was normal in terms of growth for the mutant lines, so there were no obvious confounding growth defects or effect of other induced mutations. Changes in response to C2H4 and wounding (chlorophyll loss, induced respiration, induced phenylalanine ammonia-lyase (PAL) activity) in mature heads of lettuce were variable among the three mutant lines. Selection for C2H4 insensitivity at the seedling stage did not produce mature plants that were consistently less sensitiv et o C 2H4-induced increases in PAL activity or CO2 production. However, all the selected mutated plants did have lower rates of C2H4-induced chlorophyll loss. All of the mutants differed from the wild-type in at least 3 of the 7 phenotypes measured, while one line differed in all the measured phenotypes. The apparent random distribution of induced changes observed in the mutant lines suggests that screening additional mutants may identify lines that combine a number of useful horticultural traits. # 2002 Elsevier Science B.V. All rights reserved.

Brown Bead of Broccoli. II. Relationships of the Physiological Disorder with Nutritional and Meteorological Variables

In order to investigate their relationships with brown bead, a data set composed of 48 variables characterizing the developmental rate, climate, and nutrients in the soil and in the tissues of heads of broccoli (Brassica oleracea L., Italica group) was collected from 328 plots (41 experimental fields over 3 year× 4 N fertilization level× 2 blocks). The four N treatments were 85-0-0, 85-54-0, 85-54-54, and 85-54-108, the first number indicating the N level (kg·ha-1) applied before planting; the second, N level applied 5 weeks after planting; and the last, N level applied 7 weeks after planting. Broccoli plants were either direct-seeded (26 experimental fields) or transplanted (15 experimental fields). Whether direct-seeded or transplanted, fast-developing broccoli plants showed a lower incidence of brown bead. More particularly, heads of transplanted broccoli plants experiencing warmer temperatures had a lower brown bead incidence and severity. A regular supply of water decreased the incidence and severity of the physiological disorder in both direct-seeded and transplanted broccoli plants. Low levels of Ca and high levels of Mg and K in mature broccoli head tissues were associated with a higher incidence of brown bead. Multiple-regression models were developed to predict the percentage of broccoli heads with brown bead for direct-seeded plants (R2 = 0.76; n = 104), and for transplanted plants (R2 = 0.69; n = 44). For direct-seeded broccoli, solar radiation between the button stage (head diameter of 2.5 cm) and maturity (head diameter of 10 cm), as well as soil and tissue Mg content, were among the first variables to enter the regression models. In general, more solar radiation and less precipitation translated into more heads showing brown bead symptoms. For transplanted broccoli plants, the minimum temperature from the button stage to maturity was a key variable in the prediction of the percentage of heads with brown bead and the corresponding index of severity.

Effects of PSAG12-IPT Gene Expression on Development and Senescence in Transgenic Lettuce

An ipt gene under control of the senescence-specific SAG12 promoter from Arabidopsis (P(SAG12)-IPT) significantly delayed developmental and postharvest leaf senescence in mature heads of transgenic lettuce (Lactuca sativa L. cv Evola) homozygous for the transgene. Apart from retardation of leaf senescence, mature, 60-d-old plants exhibited normal morphology with no significant differences in head diameter or fresh weight of leaves and roots. Induction of senescence by nitrogen starvation rapidly reduced total nitrogen, nitrate, and growth of transgenic and azygous (control) plants, but chlorophyll was retained in the lower (outer) leaves of transgenic plants. Harvested P(SAG12)-IPT heads also retained chlorophyll in their lower leaves. During later development (bolting and preflowering) of transgenic plants, the decrease in chlorophyll, total protein, and Rubisco content in leaves was abolished, resulting in a uniform distribution of these components throughout the plants. Homozygous P(SAG12)-IPT lettuce plants showed a slight delay in bolting (4-6 d), a severe delay in flowering (4-8 weeks), and premature senescence of their upper leaves. These changes correlated with significantly elevated concentrations of cytokinin and hexoses in the upper leaves of transgenic plants during later stages of development, implicating a relationship between cytokinin and hexose concentrations in senescence.

Possible neural control of asexually reproductive fragmentation in Enchytraeus japonensis (Oligochaeta, Enchytraeidae)

Summary The enchytraeid oligochaete Enchytraeus japonensis reproduces asexually by fragmentation under laboratory conditions. In the fragmentation process, fully-grown worms break into several fragments. Each fragment regenerates into a small but complete worm in 4 days, grows rapidly and divides again in another 10 days. We found that this fragmentation can be induced artificially by amputating the head if the worms are at least 5–6 mm in length, but not in shorter worms. The fragmentation is inducible by removing the most anterior two segments, if the worms are large enough. When a worm is cut into two, fragmentation occurs more readily in the posterior section. Moreover, even a small incision made in the ventral side of the trunk causes fragmentation in the body posterior to the incision. Immersion of the worms in water is found to inhibit fragmentation even in decapitated worms. When a worm is placed in water immediately after decapitation, the ability to fragment is gradually lost as a new head regenerates. From these results it is postulated that the ability to fragment acquired early in the growth phase is suppressed by head-derived signal(s) until spontaneous fragmentation occurs. The signals seem to be constantly transmitted through the ventral nerve cord until the head matures and lifts its blockade of fragmentation, allowing this process to proceed. At present, however, we cannot exclude the possibility that the mature head of the worm produces fragmentation-stimulating signals.

Susceptibility of broccoli cultivars to bacterial head rot: in vitro screening and the role of head morphology in resistance

Head rot is a major disease of broccoli caused by the soft rot pathogens Pseudomonas fluorescens and Erwinia carotovora. Two in vitro pathogenicity tests were evaluated as a methods to identify broccoli cultivars susceptible or resistant to bacterial head rot. One test used mature heads excised from the plant and inoculated with squares of cotton lint which had been soaked in a bacterial suspension. The other test involved stab-inoculating axenically grown seedlings. With the excised head test, susceptible cultivars showed a black soft rot, whilst less susceptible or moderately resistant cultivars showed only watersoaking, or browning and slight softening of the tissue. No cultivar was completely resistant. Ten cultivars were tested, and their susceptibility ratings corresponded with previously recorded field data, with one exception. This laboratory test could be used to screen for susceptibility to head rot in broccoli breeding programmes. The seedling test distinguished differences in aggressiveness among bacterial isolates but not cultivar susceptibility. Increasing head size correlated negatively with disease resistance. Head shape, i.e. cultivars which showed a domed shape rather than a flat shape, was positively correlated with disease resistance. Thus small domed heads are more resistant to head rot than large flat heads. Other morphological characteristics, viz. floret prominence and number, and sepal stomatal number were not correlated with host resistance.

Comparative Sequence Analysis of the DNA Packaging, Head, and Tail Morphogenesis Modules in the Temperate cos-Site Streptococcus thermophilus Bacteriophage Sfi21

The temperate Streptococcus thermophilus bacteriophage Sfi21 possesses 15-nucleotide-long cohesive ends with a 3′ overhang that reconstitutes a cos-site with twofold hyphenated rotational symmetry. Over the DNA packaging, head and tail morphogenesis modules, the Sfi21 sequence predicts a gene map that is strikingly similar to that of lambdoid coliphages in the absence of any sequence similarity. A nearly one to one gene correlation was found with the phage lambda genes Nu1 to H, except for gene B-to-E complex, where the Sfi21 map resembled that of coliphage HK97. The similarity between Sfi21 and HK97 was striking: both major head proteins showed an N-terminal coiled-coil structure, the mature major head proteins started at amino acid positions 105 and 104, respectively, and both major head genes were preceded by genes encoding a possible protease and portal protein. The purported Sfi21 protease is the first viral member of the ClpP protease family. The prediction of Sfi21 gene functions by reference to the gene map of intensively investigated coliphages was experimentally confirmed for the major head and tail gene. Phage Sfi21 shows nucleotide sequence similarity with Lactococcus phage BK5-T and a lactococcal prophage and amino acid sequence similarity with the Lactobacillus phage A2 and the Staphylococcus phage PVL. PVL is a missing link that connects the portal proteins from Sfi21 and HK97 with respect to sequence similarity. These observations and database searches, which demonstrate sequence similarity between proteins of phage from gram-positive bacteria, proteobacteria, and Archaea, constrain models of phage evolution.

The three-dimensional structure of a DNA translocating machine at 10 A resolution.

Head-tail connectors are viral substructures that are very important in the viral morphogenetic cycle, having roles in the formation of the precursor capsid (prohead), DNA packaging, tail binding to the mature head and in the infection process. Structural information on the connector would, therefore, help us to understand how this structure is related to a multiplicity of functions. Recombinant bacteriophage phi29 connectors have been crystallized in two-dimensional aggregates. An average projection image and a three-dimensional map have been obtained at 8 A and 10 A resolution, respectively, from untilted and tilted images of vitrified specimens of the two-dimensional crystals. The average projection image reveals a central mass surrounding a channel with 12 appendages protruding from the central mass. The three-dimensional map reveals a wide domain surrounded by 12 appendages that interact with the prohead vertex, and a narrow domain that interacts with the bacteriophage tail. At the junction of the two domains, 12 smaller appendages are visualized. A channel runs along the axis of the connector structure and is sufficiently wide to allow a double-stranded DNA molecule to pass through. The propeller-like structure of the phi29 connector strengthens the notion of the connector rotating during DNA packaging. The groove formed by the two lanes of large and small appendages may act as a rail to prevent the liberation of the connector from the prohead vertex during rotation.

Activity of foreign proteins targeted within the bacteriophage T4 head and prohead: implications for packaged DNA structure

The phage-derived expression, packaging, and processing (PEPP) system was used to target foreign proteins into the bacteriophage capsid to probe the intracapsid environment and the structure of packaged DNA. Small proteins with minimal requirements for activity were selected, staphylococcal nuclease (SN) and green fluorescent protein (GFP). These proteins were targeted into the T4 head by means of IPIII (internal protein III) fusions or CTS (capsid targeting sequence) fusions. Additional evidence is provided that foreign proteins are targeted into T4 by the N-terminal ten amino acid residue consensus CTS of IPIII identified in previous work. Fusion proteins were produced within host bacteria by expression from plasmids or by produc tion from recombinant phage carrying the fusion genes. Packaged fusion proteins CTS▾IPIII▾SN, CTS▾IPIII TSN, CTS▾IPIII▾GFP, CTS▾IPIII TGFP, and CTS▾GFP, where ▾ indicates a linkage peptide sequence Leu(Ile)-N-Glu cleaved by the T4 head morphogenetic proteinase gp21 during head maturation, are observed to exhibit intracapsid activity. SN activity within the head is demonstrated by loss of phage viability and by digested genomic DNA patterns visualized by gel electrophoresis when viable phage are incubated in Ca 2+. Green fluorescent phage result immediately after packaging GFP produced at 30°C and below, and continue to give green fluorescence under 470 nm light after CsCl purification. Non-fluorescent GFP-fusions are produced in bacteria at 37°C, and phage packaged with these proteins achieve a fluorescent state after incubation for several months at 4°C. GFP-packaged phage and proheads analyzed by fluorescence spectroscopy show that the mature head and the DNA-empty prohead package identical numbers of GFP-fusion proteins. Encapsidated GFP and SN can be injected into bacteria and rapidly exhibit intracellular activity. In vivo SN digestion of encapsidated DNA gives an intriguing pattern of DNA fragments by gel analysis, predominantly a repeat pattern of 160 bp multiples, reminiscent of a nucleosome digestion ladder, This quasi-limit DNA digestion pattern, reached >100-fold more slowly than the loss of titer, is invariant over a range ≤10 to 200 molecules of SN packaged per head, and independent of proteolytic cleavage of SN from the IPIII portion of the fusion, favoring a discontinuous packaged DNA structure. Rods of B-form DNA could be envisioned as protected from digestion, whereas bent or kinked DNA would be more susceptible to the diffusible SN. Such discontinuous packaged DNA structures are favored for phage T4 by a number of lines of evidence.

TRANSGENIC BROCCOLI (BRASSICA OLERACEA L. CV. ‘ITALICA’) PLANTS CONTAINING AN ANTISENSE ACC OXIDASE GENE

Agrobacterium rhizogenes harbouring the binary vector pLN35 which carries the antisense ACC oxidase gene from pTOM13 was used to transform 'Shogun' broccoli plants. Molecular analysis using polymerase chain reaction (PCR) and Southern blotting confirmed the transgenic nature of these plants. Ethylene production by the mature heads was evaluated in normal and three transgenic antisense plants using a gas chromatograph. The transgenic antisense plants TA3 (8 copies), TA4 (1 copy) and TA5 (8 copies) showed an ethylene production that was reduced by 39%, 42% and 77% respectively. Analysis of these mutants suggested that pTOM13 encodes a polypeptide similar to that involved in conversion of ACC to ethylene in broccoli.

Control of Thrips Tabaci on Cabbage, 1997

Abstract Cabbage was transplanted on 1 Jul at the Vegetable Crops Research Farm near Geneva, NY. To increase populations of thrips, a 5-ft strip of oats was planted along the length of each side of the experimental area. Plots consisted of one 10-ft row with 18-inch plant spacing. Treatments were replicated 4 times in an RCB design. A CO2 backpack sprayer with a one-row boom, having 3 nozzles per row (one over the top and one drop nozzle on each side) with TXVS-8 hollow cone tips, and delivering 31 gpa at 40 psi and 2 mph, was used to apply applications of each treatment. Javelin WG at 1.0 lb/acre was added to Admire and the check treatments to control Lepidoptera and insure readable plants at harvest. Silwet L-77 spray adjuvant was applied at 0.1% v/v with all foliar treatments. Admire (3 week post-transplant) was applied only on 22 Jul. Admire (5 week post-transplant) was applied only on 5 Aug. Metasystox-R and Warrior treatments were applied only on 14, 20, and 27 Aug. Warrior fortnightly treatments were applied only on 6, 20 Aug, 5, 15, 28 Sep, and 13 Oct. Other treatments were applied on 6, 14, 20, 27 Aug, 5, 15, 22, 28 Sep, 6 and 13 Oct. Harvest evaluations for thrips were done on 20 Oct. Evaluations for thrips damage were done by randomly selecting 2 mature heads per plot, cutting them in half along the core, and peeling back 10 layers. Each layer was assessed for the presence of thrips injury. To compare treatments, we used the average number of layers per two plants in a replicate and then analyzed these averages. Data were analyzed by a two-way ANOVA.

Expression of a testis-specific putative actin-capping protein associated with the developing acrosome during rat spermiogenesis.

Actin-capping proteins are ubiquitous components of mammalian cells. They are known to regulate the polymerization state of actin and hence indirectly control the activity of the cytoskeleton and cell shape. As part of our investigation into the molecular mechanisms that direct differentiation of a round spermatid into an elongating spermatozoa, we report on a testis-specific 1.7-kb transcript from rat testis with sequence similarities to the alpha subunit of actin-capping proteins (ACPs) from somatic cells. The transcript contains a putative cAMP-responsive motif (CREM) upstream of the initiation codon in the DNA sequence and is expressed postmeiotically, first appearing between 20 and 30 days of postnatal development. The primary amino acid sequence is 90% identical to that of a previously identified testis-specific mouse protein, gsg3, both showing approximately 40% homology to the alpha subunit of somatic ACPs. An affinity-purified polyclonal antibody to a synthetic peptide derived from the rat transcript identified a 32-kDa protein on Western blots of testicular extracts. Indirect immunofluorescent localization of the protein on frozen sections of adult rat testis showed that it is intracellular and accumulates asymmetrically in the cytoplasm of round spermatids coincident with the position of the developing acrosome. This spatial expression parallels the distribution of F-actin during sperm differentiation, supporting the hypothesis that testis-specific ACPs have an important role in determining the final shape of mature sperm heads. A disturbance in the expression of these ACPs may underlie many of the abnormalities in sperm morphology observed in infertile semen.

Wildlife in southern Everglades wetlands invaded by melaleuca (Melaleuca quinquenervia)

In the Everglades region of southeastern Florida invasion of graminoid/herhaceous wetlands by the invasive, non-native tree melateuca (Melaleuca quinquenervia) results in a closed-canopy forested wetland, with a sparse understory. Intermediate stages in this transformation include a savannah with scattered mature melaleuca trees, and mature dense melaleuca heads surrounded by areas with moderate to low levels of melaleuca. Intermediate levels of melaleuca invasion have not received any attention and were the rationale for our study. Wildlife was surveyed monthly for two years to determine species richness and abundance in wetlands with different melaleuca coverages. Wildlife included all vertebrate classes, as well as selected macro-invertebrates such as crayfish (Procambarus alleni) and grass shrimp (Paleomonetus paludosus). Species richness was highest in areas with moderate melaleuca coverage. Higher species richness is typical of sites with greater vegetative structural diversity, i.e., as in the savannah stage of invasion, as well as areas in an early stage of disturbance. The higher species richness was primarily the result of an increased number of migratory, upland birds. Many of these transient and winter-resident birds occurred at much lower abundances than in native forested habitats such as cypress swamps (Taxodium distichum), tropical hardwood hammocks, and pine (Pinus elliottii var. densa) rocklands. In contrast to the birds, number of species and the abundance of herpetofauna varied little across the melaleuca gradient. There was no shift in species composition from wetland to upland species as the melaleuca coverage increased. The number of fish species was similar across the melaleuca gradient. Unlike the herptiles, fishes were less abundant in the closed-canopy melaleuca forests indicating poorer habitat quality. Complex patterns of hydrology and gapping in the forest canopy due to wind storms and fires permitted light penetration and the persistence of productive pockets of aquatic life even within dense stands of melaleuca. The mosaic of areas with low to moderate infestations of melaleuca surrounding mature dense melaleuca stands allowed higher numbers of individuals and species to persist in or seasonally use mature dense melaleuca stands. This interspersion of habitats resulted in stands of melaleuca with ecotonal edges that provided marginal habitat for species characteristic of natural communities. Higher degree of interspersion (more edge) may also mean that the natural areas experience higher exposure to melaleuca seed source, which may result in a faster rate of spread of melaleuca. The results demonstrated that animal populations persisted in areas with disturbed vegetation, as long as critical abiotic factors (in this case hydrology) remained in operation. Areas with moderate levels of melaleuca retained species composition and productivity typical of the natural wetland community. The dominant characteristic of the faunal shifts along the gradient of increasing melaleuca coverage was increased numbers of upland, arboreal, and/or forest species, not the loss of wetland species. Regional permitting and natural resource agencies should recognize that lands with moderate levels of melaleuca may retain significant habitat quality. Restoration of such lands will demonstrate higher levels of success if the method used for melaleuca removal allows for retention of the in situ wildlife community.

Histones: genetic diversity and tissue-specific gene expression.

Histones are the major protein constituents of the chromatin of eukaryotic cell nuclei. This group of basic proteins is extremely conserved throughout evolution and includes five classes termed H1, H2A, H2B, H3 and H4. In mammals, each of these classes except H4 is subdivided into several subtypes. The most divergent class of histones is the H1 protein family, which consists of seven different subtypes, termed H1.1-H1.5, H1 degree, and H1t. The subtypes H1.2 and H1.4 are found in most somatic cell nuclei, whereas H1 degree is found in several differentiated tissues, and H1t is restricted to mammalian testicular cells. Similarly, core histone subtypes replacing the major forms of H2A, H2B or H3 have been described. Biochemical analysis of protein and RNA from different tissues and cell lines demonstrates varied patterns of expression of individual histone subtype genes. Moreover, antibodies against specific histone subtypes and in situ hybridization with subtype-specific probes indicate that the expression of histone subtype genes is in several cases modulated in a tissue-specific manner. This is particularly evident at the different stages of spermatogenesis when chromatin undergoes substantial reorganization, which finally results in the highly condensed state of chromatin of the mature sperm head.

Control of Thrips Tabaci on Cabbage, 1996

Abstract Cabbage was transplanted on 27 Jun at the Vegetable Crops Research Farm near Geneva, NY. To increase populations of thrips, a 5-ft strip of oats was planted along the length of each side of the experimental area. Plots consisted of two 10-ft rows on 36-inch centers with 18-inch plant spacing. Treatments were replicated 4 times in an RCB design. A backpack sprayer with a one-row boom, having 3 nozzles per row with HC 12 hollow cone tips, and delivering 30 gpa at 40 psi and 2 mph, was used to apply weekly applications of each treatment. Javelin at 1.0 lb./acre was added to Admire and the check treatments to control Lepidoptera and insure readable plants at harvest. Silwet sticker-spreader was applied at 0.1 % v/v with all foliar treatments. Admire was applied only on 7 Jul. Metasystox-R treatments were applied only on 6, 13 and 20 Sep. Provado was applied only on 6, 13, 20, 26 Sep and 1 Oct. Other treatments were applied on 7, 14, 22, 30 Aug, 6, 13, 20, 26 Sep 1, 10 and 17 Oct. Harvest evaluations for thrips were made on 28 Oct. Evaluations for thrips damage were made by randomly selecting 2 mature heads per plot, cutting them in half along the core, and peeling back 10 layers. Each layer was assessed for the presence of thrips damage. For layers damaged, we used the average number of layers per two plants in a replicate and then analyzed these averages. Data were analyzed by a two-way ANOVA.

Control of Lepidopterous Pests, 1994

Abstract Transplants were set out on 21 Mar (Test 1) and 12 May (Test 2) at the UG Coastal Plain Experiment Station Ponder Farm near Tifton. Plant spacing was 12 inches in the row and 36 inches between rows. Plots were two rows wide and 50 ft long. Treatments were replicated four times in a RCB design. Insecticides were applied with a two-row boom equipped with three Spraying Systems TX18 hollow cone nozzles per row delivering 50 gpa at a pressure of 100 psi. A surfactant, Valent X-77 was included with all treatments at a concentration of 0.25%. Application dates were 25 Apr, 2, 9, 17, and 25 May (Test 1), and 1, 8, 13, 21 June; 8 and 13 July (Test 2). Larval counts on five plants per plot were made on 29 Apr, 5, 13 May (Test 1); 3, 10, 16, 24 Jun and 12 July (Test 2). On 30 May (Test 1) and 21 July (Test 2), market quality was determined by scoring 10 mature heads per plot using a 0-5 scale as given in the Table. Data were subjected to ANOVA and means were separated by LSD (P = 0.05).

Analysis of the complete nucleotide sequence and functional organization of the genome of Streptococcus pneumoniae bacteriophage Cp-1.

Cp-1, a bacteriophage infecting Streptococcus pneumoniae, has a linear double-stranded DNA genome, with a terminal protein covalently linked to its 5' ends, that replicates by the protein-priming mechanism. We describe here the complete DNA sequence and transcriptional map of the Cp-1 genome. These analyses have led to the firm assignment of 10 genes and the localization of 19 additional open reading frames in the 19,345-bp Cp-1 DNA. Striking similarities and differences between some of these proteins and those of the Bacillus subtilis phage phi 29, a system that also replicates its DNA by the protein-priming mechanism, have been revealed. The genes coding for structural proteins and assembly factors are located in the central part of the Cp-1 genome. Several proteins corresponding to the predicted gene products were identified by in vitro and in vivo expression of the cloned genes. Mature major head protein from the virion particles results from hydrolysis of the primary gene product at the His-49 residue, whereas the phage gene is expressed in Escherichia coli without modification. We have also identified two open reading frames coding for proteins that show high degrees of similarity to the N- and C-terminal regions, respectively, of the single tail protein identified in phi 29. Sequencing and primer extension analysis suggest transcription of a small RNA showing a secondary structure similar to that of the prohead RNA required for the ATP-dependent packaging of phi 29 DNA. On the basis of its temporal expression, transcription of the Cp-1 genome takes place in two stages, early and late. Combined Northern (RNA) blot and primer extension experiments allowed us to map the 5' initiation sites of the transcripts, and we found that only three genes were transcribed from right to left. These analyses reveal that there are also noticeable differences between Cp-l and phi 29 in transcriptional organization. Considered together, the observations reported here provide new tangible evidence on phylogenetic relationships between B. subtilis and S. pneumoniae.

Control of Thrips Tabaci on Cabbage, 1995

Abstract Cabbage was transplanted on 13 Jun at the Vegetable Crops Research Farm near Geneva, NY. Plots consisted of two 10-ft rows on 36-inch centers with 18-inch plant spacing. Treatments were replicated 4 times in an RCB design. A backpack sprayer with a one-row boom, having 3 nozzles per row with HC 12 hollow cone tips, and delivering 30 gal/acre at 40 psi and 2 mph, was used to apply weekly applications of each treatment. Javelin at 1.0 lb/acre was added to Admire, Cygon and the check treatments to control Lepidoptera and insure readable plants at harvest. Bond sticker-spreader was applied at 0.1% v/v with all treatments. Admire was applied on only 7 Jul. Metasystox R was applied only on 6, 13 and 20 Sept. Other treatments were applied on 26 Jul, 2, 9, 16, 24, 30 Aug and 6, 13, 20, 27 Sept and 4, 11 Oct. Harvesi evaluations for thrips were made on 19 Oct. Evaluations for thrips damage were made by randomly selecting 2 mature heads per plot, cutting them in half along the core, and peeling back 10 layers. Each layer was assessed for the presence of thrips injury. The overall damage rating (intensity of injury on each leaf plus the number of layers injured) was also made on a scale of 0 (no damage) to 4 (each of the 10 leaves severely injured). Data were analyzed by a two-way ANOVA. For analysis of damage ratings we used the average number of layers per two plants in a replicate, transformed this to a rank, and analyzed ranks. For layers injured, we used the average number of layers per two plants in a replicate and then analyzed these averages No treatments had significantly fewer layers damaged compared to the control. Between treatments, Metasystox R at 3 pt./acre and Mustang at 0.0375 Ib.Al/acre had significantly fewer layers damaged than Ammo at 0.08 Ib.Al/acre, Ambush at 0.1 Ib.Al/acre, Cygon at 0.5 Ib.Al/acre, or Asana at 0.05 Ib.Al/acre. Only Metasystox R at 3 pt./acre and Mustang at 0.0375 Ib.Al/acre had a significantly lower damage ranking compared to the control. Between treatments, Metasystox R and Mustang had significantly lower damage rankings than Ammo at 0.08 Ib.Al/acre, Ambush at 0.1 Ib.Al/acre, Cygon at 0.5 Ib.Al/acre, or Asana at 0.05 Ib.Al/acre. No phytotoxicity was observed in any of the treatments.

The key to successful second year white clover seed crops

In recent years there has been an increase in the number of white clover seed crops taken for a second harvest. Traditionally yields from second year crops are substantially lower than first year crops. A trial was established investigating techniques to increase yields in second year crops. The trial was located in a dryland crop of white clover (cv. Grasslands Demand) 4 km east of Methven, mid Canterbury. It involved 10 herbicide treatments and 8 'inter-row' treatments arranged in a split block design. Number of mature flower heads were recorded on all treatments at harvest as an indirect estimate of yield. Additionally, selected treatments were cut and collected using a rotary type mower, threshed, and machine dressed for direct estimates of seed yield. Flower number and machine dressed seed yield were significantly (P

Assemblyin Vitroof Bacteriophage HK97 Proheads

Bacteriophage HK97 is a lambdoid phage with a head assembled from 415 copies of a 42 kDa subunit arranged in an icosahedrally symmetrical lattice with a triangulation number of 7. Prohead I, the first shell structure in the assembly pathway, is composed of 42 kDa coat protein subunits that have not yet undergone the proteolytic cleavage, conformational changes, and covalent cross-linking steps that occur later in the assembly of mature heads. Prohead I can be efficiently dissociated into capsomeres by treatment with 2 M KCl. The resulting capsomeres are a mixture of two species, identified as pentamers and hexamers of the 42 kDa subunit. These capsomeres were also detected as the products of chaperonin-assisted renaturation of 42 kDa polypeptidein vitroat room temperature or in the course of self folding and assemblyin vitroat 0 °C. Pentamer and hexamer capsomeres can be interconvertedin vitroby manipulating solvent conditions, and this makes it possible to carry out thein vitroshell assembly reaction at different input ratios of hexamer to pentamer. The Prohead I structures produced are always the normal (T= 7) size regardless of the input pentamer to hexamer ratio. Assembly is most efficient when the pentamer to hexamer ratio is 1:5 (a mass ratio of 1:6), or the same as the capsomere ratio in aT= 7 shell.