Transformation of cucumber tissues by microprojectile bombardment: identification of plants containing functional and non-functional transferred genes.

The microprojectile bombardment method was used to transfer DNA into embryogenic callus of cucumber (Cucumis sativus), and stably transformed cucumber plant lines were obtained. A total of 107 independently regenerated cucumber plants were assayed for the presence and expression of the transferred Nos-NPTII gene (encoding nopaline synthase-neomycin phosphotransferase II). Genomic blot hybridization analyses showed that a high percentage (16%) of the cucumber plants were transformed with Nos-NPTII; however, only about 25% of these transgenic plants expressed Nos-NPTII. Inactivity of Nos-NPTII in many of the transformed cucumber plants may be associated with the transfer of multiple copies of Nos-NPTII. PCR and genomic blot hybridization analyses were used to show that the transferred gene was inherited in the subsequent plant generation.     

Ruby laser-assisted hair removal success in relation to anatomic factors and melanin content of hair follicles.

Ruby laser-assisted hair removal is thought to work via selective photothermolysis, which relies on light reaching the deeper layers of skin, and the absorption of light by the target chromophore, melanin. It is therefore possible that efficacy of treatment is affected by anatomic factors that determine the amount of light reaching the hair bulbs (i.e., skin color, depth of intracutaneous hair, epidermal thickness and dermal density) and the melanin content of hair. To examine this hypothesis, a prospective study was performed. Forty-eight volunteers were treated with the Chromos 694 Depilation Ruby Laser at a single standard fluence of 11 J/cm2. Treatment efficacy was determined by measuring hair density at 3 and 7 months after treatment. Epidermal depth and dermal density were measured from 2-mm biopsies taken before treatment, and the intracutaneous hair length was determined from plucked hair. Skin color was assessed using a spectrophotometer, and melanin content of dissolved hair was assessed using spectrophotometry. Efficacy of treatment for each patient was compared with the patient's age, intracutaneous hair length, epidermal depth, dermal density, skin color, and total melanin content and relative eumelanin content of hair. No correlation was found between the efficacy of treatment and age and the various anatomic factors. Patients with higher eumelanin content in their hair had better long-term results (Spearman rank test, p = 0.00219). The results suggested that the efficacy of treatment did not depend solely on the amount of laser light penetrating the skin but correlated well with the eumelanin content of hair. The clinical implication of this finding is discussed.     

Mechanisms of innate resistance to Toxoplasma gondii infection.

The interaction of protozoan parasites with innate host defences is critical in determining the character of the subsequent infection. The initial steps in the encounter of Toxoplasma gondii with the vertebrate immune system provide a striking example of this important aspect of the host-parasite relationship. In immuno-competent individuals this intracellular protozoan produces an asymptomatic chronic infection as part of its strategy for transmission. Nevertheless, T. gondii is inherently a highly virulent pathogen. The rapid induction by the parasite of a potent cell-mediated immune response that both limits its growth and drives conversion to a dormant cyst stage explains this apparent paradox. Studies with gene-deficient mice have demonstrated the interleukin-12 (IL-12)-dependent production of interferon gamma (IFN-gamma) to be of paramount importance in controlling early parasite growth. However, this seems to be independent of nitric oxide production as mice deficient in inducible nitric oxide synthase (iNOS) and tumour necrosis factor receptor were able to control early growth of T. gondii, although, they later succumbed to infection. Nitric oxide does, however, seem to be important in controlling persistent infection; treating chronic infection with iNOS metabolic inhibitors results in disease reactivation. Preliminary evidence implicates neutrophils in effector pathways against this parasite distinct from that described for macrophages. Once initiated, IL-12-dependent IFN-gamma production in synergy with other proinflammatory cytokines can positively feed back on itself to induce ''cytokine shock''. Regulatory cytokines, particularly IL-10, are essential to down-regulate inflammation and limit host pathology.     

Herpesviruses: a study of parts

Dormancy, an adaptation to survival in a hostile environment, is a trait common to herpesviruses. Two other features are a large (0.1-0.25 Mb) and mutile (inherently easily mutable) genome. The complete nucleotide sequences of four herpesviruses have recently been determined. This database is unparalleled in allowing the comparative evolutionary study of a complex group of viruses in eukaryotes. In this article, we examine aspects of herpesvirus diversity in the light of recent studies which have revealed characteristics that unify the family at the genetic level.     

Long-distance migration and homing after displacement in the green turtle (Chelonia mydas): a satellite tracking study

Four green turtle females were tracked by satellite during their post-reproductive migration in the South China Sea. Three of them reached their feeding grounds 923–1551 km distant. During nesting activity, a female was displaced twice, and her return trips to the nesting beach from 11 and 284 km were tracked by a direction-recording data-logger and by satellite, respectively. Part of the journeys occurred coastwise, indicating that leading geographical features had been utilised. The straightness of the turtles' tracks in open seas, both over shallow and deep waters, and their ability to pinpoint distant targets and home after displacement off their usual routes, provides circumstantial evidence for a true navigation mechanism.Abbreviation PTT platform transmitter terminal     

Continuous growth of human tumor cell lines in serum-free media

Summary Five human tumor cell lines were studied for growth factor requirements and for replication in serum-free media. Of the five tumor lines HT-29 (colon carcinoma), TWI (melanoma), A-549 (lung carcinoma), Panc-1, (carcinoma of the pancreas) and EJ, (bladder carcinoma) only HT-29 and TWI grew in the serum-free medium (SFM). In a series of additional experiments, a combination of transferrin (5 μg/ml), insulin (5 μg/ml), triiodothyronine (2×10⁻¹⁰ M), epidermal growth factor (20 ng/ml), and selenium (5 ng/ml) was added to Chee’s essential medium (CEM) without serum (C-TITES medium). The C-TITES modification of CEM was found to allow optimal replication of HT-29 and TWI cells. Both HT-29 and TWI cells have replicated continuously in C-TITES medium for periods of more than 15 mo. These cells replicate with slightly lower doubling times than in CEM supplemented with 10% fetal bovine serum. Deletion of insulin or transferrin from the C-TITES medium resulted in cessation of cell growth of HT-29 and TWI. HT-29 assumed a somewhat rounded morphology, whereas TWI grew with the characteristic fibroblastic morphology in C-TITES medium. Cell line EJ did not grow in C-TITES medium. The other two cell lines, A-549 and Panc-1, grew in C-TITES medium but their growth rate was much slower than that in SSM. Availability of cell lines that can be propagated in serum-free, hormone-supplemented medium may aid in the study of the mechanisms by which hormones influence cell growth. This work was supported by Veterans Administration Research Awards to two of the authors (Karimullah A. Zirvi and George J. Hill) and grant no. CA-37138 from the National Cancer Institute.     

DIE NEUTRALIS and LATE BLOOMER 1 Contribute to Regulation of the Pea Circadian Clock

The DIE NEUTRALIS (DNE) locus in garden pea (Pisum sativum) was previously shown to inhibit flowering under noninductive short-day conditions and to affect a graft-transmissible flowering signal. In this study, we establish that DNE has a role in diurnal and/or circadian regulation of several clock genes, including the pea GIGANTEA (GI) ortholog LATE BLOOMER 1 (LATE1) and orthologs of the Arabidopsis thaliana genes LATE ELONGATED HYPOCOTYL and TIMING OF CHLOROPHYLL A/B BINDING PROTEIN EXPRESSION 1. We also confirm that LATE1 participates in the clock and provide evidence that DNE is the ortholog of Arabidopsis EARLY FLOWERING4 (ELF4). Circadian rhythms of clock gene expression in wild-type plants under constant light were weaker in pea than in Arabidopsis, and a number of differences were also seen in the effects of both DNE/ELF4 and LATE1/GI on clock gene expression. Grafting studies suggest that DNE controls flowering at least in part through a LATE1-dependent mobile stimulus, and dne mutants show elevated expression of a FLOWERING LOCUS T homolog under short-day conditions. However, the early flowering of the dne mutant is not associated with altered expression of a previously described CONSTANS-like gene. Collectively, our results characterize the clock system and reveal its importance for photoperiod responsiveness in a model legume.