Seasonal Evolution of the Quality of Fresh Glasshouse Tomatoes under Mediterranean Conditions, as Affected by Air Vapour Pressure Deficit and Plant Fruit Load

Changes in yield and quality of fresh tomatoes in response toair vapour pressure deficit (VPD) and plant fruit load werestudied under Mediterranean summer conditions. Plants thinnedto three or six fruits per truss were grown in two compartments,one at a VPD below 1.5 kPa, the other without VPD control. Theseasonal trend in fruit yield and quality was assessed fromApril to September by weekly measurement of number, fresh weightand dry matter content of harvested fruits, together with theoccurrence of blossom-end-rot (BER) and cracking. On two occasions,in July and September, sugar and acid content was measured atthree ripening stages. The seasonal decrease in fresh yieldwas attenuated at low VPD, because of higher individual fruitfresh weight, especially at low fruit load. Low VPD decreasedoccurrence of BER but like low fruit load, it increased fruitcracking. Fruit dry matter content was lower at low VPD, butwas unaffected by fruit load. Sugar content and the ratio ofsugars:acids was increased at high VPD and low fruit load, withinteractive effects depending on season and ripening stage.The influence of VPD on acid content differed with fruit loadand also changed during ripening and between seasons. Resultsshowed that water was the main limiting factor for growth offruits picked in July; at this time, reducing fruit load topromote mean fruit size had negative effects on BER and cracking.Reducing VPD reduced BER but had a negative effect on crackingand diluted both the dry matter and sugar content. For fruitsharvested later in summer, these negative effects were attenuatedbecause fruit growth was also carbon limited. Copyright 2000Annals of Botany Company Lycopersicon esculentum Mill., tomato, water and carbon stress, yield, quality, dry matter, sugar, acid, BER, volatile composition     

Tissue and Cellular Distribution of Glutamine Synthetase in Roots of Pea (Pisum sativum) Seedlings

The effect of nitrate application on glutamine synthetase activity in roots of pea (Pisum sativum L.) seedlings (2 weeks old) was studied. Separation of organelles from root fragments by sucrose density-gradient centrifugation revealed that both nitrite reductase and glutamine synthetase activities increased in root plastids as a response to nitrate application and that no such response was induced by ammonium application. Glutamine synthetase activity was also found to increase in plastids with distance from apex in nitrate-treated plants, the highest specific activity being located in the fourth 1-centimeter segment. Separation by SDS-PAGE and characterization by Western blotting showed that cytosolic glutamine synthetase contains one subunit polypeptide (28 kilodaltons) and that plastid glutamine synthetase contains both the 38-kilodalton subunit and a heavier subunit. When nitrate was present in the nutrient solution, the heavier subunit increased in abundance in protein fractions obtained from purified root plastids.     

The molecular structure of a 4'-epiadriamycin complex with d(TGATCA) at 1.7A resolution: comparison with the structure of 4'-epiadriamycin d(TGTACA) and d(CGATCG) complexes.

The structure of the complex between d(TGATCA) and the anthracycline 4'-epiadriamycin has been determined by crystallographic methods. The crystals are tetragonal, space group P4(1)2(1)2 with unit cell dimensions of a = 28.01, c = 52.95A. The asymmetric unit consists of one strand of hexanucleotide, one molecule of 4'-epiadriamycin and 34 waters. The R-factor is 20.2% for 1694 reflections with F greater than or equal to 2 sigma F to 1.7A. Two asymmetric units associate to generate a duplex complexed with two drug molecules at the d(TpG) steps of the duplex. The chromophore intercalates between these base pairs with the anthracycline amino-sugar positioned in the minor groove. The double helix is a distorted B-DNA type structure. Our structure determination of d(TGATCA) complexed to 4'-epiadriamycin allows for comparison with the previously reported structures of 4'-epiadriamycin bound to d(TGTACA) and to d(CGATCG). The three complexes are similar in gross features and the intercalation geometry is the same irrespective of whether a d(CpG) or d(TpG) sequence is involved. However, the orientation of the amino-sugar displays a dependence on the sequence adjacent to the intercalation site. The flexibility of this amino-sugar may help explain why this class of antibiotics displays a relative insensitivity to base sequence when they bind to DNA.     

Reversibility of IUdR resistance to sensitivity to an HSV1 strain in experimental keratitis in rabbits]

During 7 serial passages of Herpes Simplex Virus (HSV1) in rabbit cornea treated with idoxuridine (IUdR) (P1 to P7), the emergence of resistance had been obtained from P3. The reversion towards IUdR sensitivity has been investigated from either viral population P3 or P6 by 6 serial passages in rabbit cornea treated by Vaseline (V1 to V6). From viral population P3, the reversion to IUdR sensitivity has been obtained at V4. In contrast, from viral population P6, the IUdR resistance was conserved from V1 to V6. In vitro, on Vero cells, the effective doses 50% (ED50) and 90% (ED90), determined by dye uptake assay and plaque reduction assay, confirmed the reversibility towards IUdR sensitivity obtained from P3 and the stability of IUdR resistance from P6.     

Temporal Patterns of Reported Single-Vehicle Car and Truck Accidents in Texas, U.S.A. During 1980-1983

Reported single car and truck accidents due specifically to driver 'fatigue' for the 4-year span of 1980-1983 were analyzed for 24-hr, 7-d and 1-yr patterns. Three types of data were examined: (1) accidents in rural Texas, (2) accidents only in San Antonio, the fourth largest city in Texas and (3) accident ratio (number of accidents per time interval divided by traffic volume for the interval) in this city.

A statistically significant seasonal variation of relatively low amplitude with peaks in May and July was detected only for accidents in rural areas. High-amplitude periodicities of 7 d were evident in all the data sets, with a peak on the weekend. A very prominent 24-hr pattern was detected as well, with the acrophase determined by single cosinor around 0300. A slight secondary peak in accidents, around 1500, was evident in the data from the rural areas. This secondary peak represented a 12-hr rhythm in addition to the 24-hr. Overall, features of the temporal patterns in accidents over 24 hr and over the year in urban and rural areas differed only slightly. Accident ratios yielded results similar to accident frequencies. However, with regard to the rural data, the shape of the 24-hr temporal pattern varied with driver age; older drivers exhibited a flatter curve with a more pronounced afternoon rather than early morning (around 0300) peak.     

Identification of sites within gp41 that serve as targets for antibody-dependent cellular cytotoxicity by using human monoclonal antibodies.

In an effort to determine the functional activity of anti-HIV-1 human mAb and to define the epitopes against which they are directed, supernatants from 10 EBV-transformed lymphoblastoid cell lines producing mAb to HIV were tested. Five clones producing mAb to gp41 and five producing mAb to p24 were identified. The anti-HIV-1 human mAb were tested in neutralization and cell fusion assays in the form of cell culture supernatants at concentrations ranging from 1.7 to 22.0 micrograms/ml. None of the human mAb were found either to inhibit HIV-1-(IIIB or RF) associated cell fusion or to neutralize HIV-1 (IIIB) infection of AA5 cells. All human mAb were additionally tested in 6 h 51Cr release assays for their ability to direct HIV-1 specific antibody-dependent cellular cytotoxicity (ADCC). For ADCC assays, PBMC were isolated from healthy seronegative donors and used as effector cells. HIV-1 infected (IIIB, RF, and MN) CEM.NKR cells as well as CEM.NKR cells with purified gp120 adsorbed onto their surface served as targets. None of the anti-p24 mAb mediated ADCC. In contrast, three of the anti-gp41 mAb were able to direct a significant level of ADCC against each of the infected targets, but as expected, failed to lyse gp120 adsorbed cells. To define the specific epitopes against which the anti-gp41 mAb were directed, seven small peptides homologous to regions within the extracellular domain of gp41 were synthesized. Using RIA, two of the mAb could be mapped. The most effective ADCC-directing human mAb bound to a peptide comprising amino acids 644-663, whereas the least effective ADCC directing anti-gp41 human mAb bound to a region within the immunodominant portion of gp41 outlined by amino acids 579-604. Together, these results for the first time assign a functional activity to human mAb directed at specific regions within gp41 by demonstrating that areas within this molecule can serve as targets for ADCC.     

Rat liver microsomal progesterone metabolism: evidence for differential troleandomycin and pregnenolone 16 alpha-carbonitrile inductive effects in the cytochrome P-450 III family

The effect of Troleandomycin (TAO) and pregnenolone 16 alpha-carbonitrile (PCN) on the hepatic microsomal progesterone metabolism in the rat is evaluated. Over thirteen hydroxylated progesterone derivatives are detected, including the novel 6 beta, 21-, 6 beta, 16 alpha-, 6 beta, 16 beta- and 2,21-dihydroxy derivatives, suggesting the induction of several cytochrome P-450 isozymes. PCN treatment results overall in an augmented production of progesterone metabolites whereas TAO treatment both induces and represses specific hydroxylase activities. Progesterone metabolism with purified isozymes isolated from liver microsomes from TAO and PCN treated rats differs significantly from that observed with intact microsomes, reflecting the complexity of the induction pattern of the cytochrome P-450 III family.     

Localization of sequences regulating ancestral and acquired sites of esterase6 activity in Drosophila melanogaster

We have broadly defined the DNA regions regulating esterase6 activity in several life stages and tissue types of D. melanogaster using P- element-mediated transformation of constructs that contain the esterase6 coding region and deletions or substitutions in 5' or 3' flanking DNA. Hemolymph is a conserved ancestral site of EST6 activity in Drosophila and the primary sequences regulating its activity lie between -171 and -25 bp relative to the translation initiation site: deletion of these sequences decrease activity approximately 20-fold. Hemolymph activity is also modulated by four other DNA regions, three of which lie 5' and one of which lies 3' of the coding region. Of these, two have positive and two have negative effects, each of approximately twofold. Esterase6 activity is present also in two male reproductive tract tissues; the ejaculatory bulb, which is another ancestral activity site, and the ejaculatory duct, which is a recently acquired site within the melanogaster species subgroup. Activities in these tissues are at least in part independently regulated: activity in the ejaculatory bulb is conferred by sequences between -273 and -172 bp (threefold decrease when deleted), while activity in the ejaculatory duct is conferred by more distal sequences between -844 and -614 bp (fourfold decrease when deleted). The reproductive tract activity is further modulated by two additional DNA regions, one in 5' DNA (-613 to -284 bp; threefold decrease when deleted) and the other in 3' DNA (+1860 to +2731 bp; threefold decrease when deleted) that probably overlaps the adjacent esteraseP gene. Collating these data with previous studies suggests that expression of EST6 in the ancestral sites is mainly regulated by conserved proximal sequences while more variable distal sequences regulate expression in the acquired ejaculatory duct site.      

Phylogenetic diversification of immunoglobulin genes and the antibody repertoire

Immunoglobulins are encoded by a large multigene system that undergoes somatic rearrangement and additional genetic change during the development of immunoglobulin-producing cells. Inducible antibody and antibody-like responses are found in all vertebrates. However, immunoglobulin possessing disulfide-bonded heavy and light chains and domain-type organization has been described only in representatives of the jawed vertebrates. High degrees of nucleotide and predicted amino acid sequence identity are evident when the segmental elements that constitute the immunoglobulin gene loci in phylogenetically divergent vertebrates are compared. However, the organization of gene loci and the manner in which the independent elements recombine (and diversify) vary markedly among different taxa. One striking pattern of gene organization is the "cluster type" that appears to be restricted to the chondrichthyes (cartilaginous fishes) and limits segmental rearrangement to closely linked elements. This type of gene organization is associated with both heavy- and light-chain gene loci. In some cases, the clusters are "joined" or "partially joined" in the germ line, in effect predetermining or partially predetermining, respectively, the encoded specificities (the assumption being that these are expressed) of the individual loci. By relating the sequences of transcribed gene products to their respective germ-line genes, it is evident that, in some cases, joined-type genes are expressed. This raises a question about the existence and/or nature of allelic exclusion in these species. The extensive variation in gene organization found throughout the vertebrate species may relate directly to the role of intersegmental (V<==>D<==>J) distances in the commitment of the individual antibody-producing cell to a particular genetic specificity. Thus, the evolution of this locus, perhaps more so than that of others, may reflect the interrelationships between genetic organization and function.