Differentiation of the epidermis in turtle: an immunocytochemical, autoradiographic and electrophoretic analysis

Proteins involved in the process of cornification of turtle epidermis are not well known. The present immunocytochemical, electrophoretic and autoradiographic study reports on the localization patterns and molecular weights of keratins, which are cornification proteins, and of tritiated histidine in turtle epidermis. Alpha-keratins with a molecular weight of 40-62 kDa are present in the epidermis. Beta-keratin is mainly detectable in the stratum corneum of the carapace and plastron, but is rarely present or even absent in the corneous layer of limb, tail and neck epidermis. After electrophoresis and immunoblotting with an antibody against chicken scale beta-keratin, bands at 15-17, 22-24, and 36-38 kDa appeared. This antibody recognized weaker bands at 38-40 and 58-60 kDa in the soft epidermis. After reduction and carboxymethylation of proteins extracted from carapace and plastron, but not of proteins from the soft epidermis, protein bands at 15-17 and 35-37 kDa were found when using the anti-beta 1-keratin antibody. Loricrin-, filaggrin-, sciellin-, and transglutaminase-like immunostaining was detectable only in the transitional and lowermost corneous layers of the soft epidermis. Vesicular bodies in the transitional layer were immunolabeled by the anti-loricrin antibody, and weakly by the anti-filaggrin and anti-transglutaminase antibodies. In immunoblots, the anti-loricrin antibody reacted with a major band at 50-54 kDa in both carapace-plastron and soft epidermis. The anti-sciellin antibody detected major bands at 38-40 and 50 kDa in hard epidermis, and at 50 and 54-56 kDa in soft epidermis. Filaggrin-like immunostained bands were observed at 50-55 and 62-64 kDa. This immunostaining was probably due to a common epitope in filaggrin and some keratins. Histidine was evenly incorporated in the epidermis, and the ultrastructural study showed random labeling, often associated with keratin bundles of alpha and beta-keratinocytes. Histidine-labeled protein bands were not found in the carapace-plastron. In the soft epidermis, weakly labeled bands at 15-20, 25, and 45-60 kDa were found occasionally. The latter bands probably represented neo-synthesized keratins as was also indicated by the ultrastructural autoradiographic analysis. In conclusion, our study suggests that proteins with epitopes that they have in common with cornification proteins of mammalian epidermis are also present in the epidermis of turtle.     

TYLCSV DNA, but not infectivity, can be transovarially inherited by the progeny of the whitefly vector Bemisia tabaci (Gennadius)

The transovarial transmission of two species of begomovirus, Tomato yellow leaf curl virus (TYLCV) and Tomato yellow leaf curl Sardinia virus (TYLCSV), through generations of Bemisia tabaci of the B and Q biotypes has been investigated. Different life stages of the progeny of viruliferous female whiteflies have been analysed by PCR detection of viral DNA and infectivity tests. Our results indicate that TYLCSV DNA can be detected in eggs and nymphs, and to a lesser extent adults, of the first-generation progeny. Infectivity tests using a large number of adult progeny of the first, second, and third generation indicate that even when viral DNA is inherited, infectivity is not. For TYLCV, neither viral DNA nor infectivity were associated with the progeny of viruliferous female whiteflies. Because the inherited viral DNA is unable to give rise to infections, the transovarial transmission of TYLCSV DNA appears to have no epidemiological relevance.     

Diversity of genomic breakpoints in TFG-ALK translocations in anaplastic large cell lymphomas: identification of a new TFG-ALK(XL) chimeric gene with transforming activity

Anaplastic large cell lymphomas are associated with chromosomal aberrations involving the anaplastic lymphoma kinase (ALK) gene at 2p23 that result in the expression of novel chimeric ALK proteins with transforming properties. In most of these tumors, the t(2;5)(p23;q35) generates the NPM-ALK fusion gene. However, several studies have now demonstrated that genes other than NPM may be fused to the ALK gene. We have recently described two different ALK rearrangements involving the TRK-fused gene (TFG) in which the same portion of ALK was fused to different length fragments of the 5' TFG region. These two rearrangements encoded chimeric proteins of 85 kd (TFG-ALK(S)) and 97 kd (TFG-ALK(L)), respectively. In this study, we have identified a new ALK rearrangement in which the catalytic domain of ALK was fused to a larger fragment of the TFG gene (TFG-ALK(XL)), encoding for a fusion protein of 113 kd. Genomic analysis of these three TFG-ALK rearrangements revealed that the TFG breakpoints occur at introns 3, 4, and 5, respectively, whereas the ALK breakpoints always occur in the same intron. No homologous regions or known recombination sequences were found in these regions. Transfection experiments using NIH-3T3 fibroblasts showed a similar transforming efficiency of TFG-ALK variants compared with NPM-ALK. In addition, in common with NPM-ALK, the TFG-ALK proteins formed stable complexes with the signaling proteins Grb2, Shc, and PLC-gamma. In conclusion, these findings indicate that the TFG may use a variety of intronic breakpoints in ALK rearrangements generating fusion proteins of different molecular weights, but with similar transforming potential than NPM-ALK.     

Interaction between rod and cone systems in dichoptic visual masking

The brightness of a brief flash of light is reduced by the suitable presentation of a second flash in an adjacent region of the visual field. This making effect (metacontrast) can be induced dichoptically, that is with the test flash presented to one eye and the masking flash to the other. By a suitable choice of wavelengths and conditioning field, the test flash may be arranged to effectively stimulate only rod receptors and the masking flash only cone receptor. A dichoptic masking effect is still obtained.     

Transmission of a spotted fever group rickettsia by Amblyomma hebraeum (Acari: Ixodidae)

Amblyomma hebraeum, a cattle tick common in southern Africa, was demonstrated to be capable of maintaining an infection with an unclassified spotted fever group rickettsia both transtadially and transovarially. All feeding stages of the tick transmitted the infection to rabbits. The rickettsia was isolated and found to be serotypically distinct from three strains of Rickettsia conorii by microimmunofluorescence. Rabbit serum titers were found to be higher with indirect fluorescent antibody (IFA) tests using the Amblyomma isolate than with those using a commercially available IFA test for R. conorii.     

Effect of orally administered monoclonal antibody on persistent Cryptosporidium parvum infection in scid mice.

Scid mice, persistently infected after exposure to 10(7) Cryptosporidium parvum oocysts, were treated daily for 14 to 17 days with 0.4 mg of monoclonal antibody (mAb) 17.41 administered by the oral route. Mice receiving mAb 17.41 shed significantly fewer (P < 0.005) C. parvum oocysts than scid mice receiving isotype control mAb. Intestinal (but not gastric) infectivity scores were also reduced for scid mice treated with mAb 17.41 (P < 0.01).     

Effect of spleen cell populations on resolution of Cryptosporidium parvum infection in SCID mice.

Persistent infection was established in SCID mice given 10(7) Cryptosporidium parvum oocysts. Nine groups of infected SCID mice were inoculated with 10(6), 10(5), or 10(4) total spleen cells, CD8-depleted spleen cells, or CD4-depleted spleen cells from naive BALB/c donors. Infection was significantly reduced in all treatment groups. The most profound effect occurred with spleen cell preparations containing CD4 T lymphocytes but depleted of CD8 T lymphocytes.