Cold-induced Chromosome Regions and Karyosystematics in Sambucus and Viburnum

The genera Viburnum, Sambucus and Lonicera have been investigated for chromosome number and karyomorphology including Giemsa-C-banding, fluorochrome (DAPI/CMA) banding and cold treatment. Cold-induced undercontracted chromosome regions (CIRs) are found in Viburnum and Sambucus for the first time and are apparently identical with larger hc regions, shown by Giemsa C-banding. Certain narrow C-bands are not cold-sensitive. CIRs frequently react brightly CMA-positive in Viburnum and Sambucus, while DAPI fluorescence is virtually ineffective. The occurrence of CIRs within plants is possibly linked to certain nuclear characters such as large chromosomes and continuous condensation behaviour. Cold-induction has possibly also some influence on euchromatin condensation characteristics in prophasic chromosomes. Several karyological characters point to a closer relationship between Viburnum, Sambucus and Adoxa: Relatively large chromosomes, continuous condensation behaviour, reticulate to semireticulate interphase nuclei and presence of CIRs. These genera appear isolated from Lonicera and the Caprifoliaceae s.str., which differ remarkably in karyomorphology.     

Hatching plasticity in a Southeast Asian tree frog mitigates submergence-induced mortality

Environmentally cued hatching has been well-documented in amphibians in response to a wide range of abiotic and biotic factors. The hatching of terrestrial amphibian eggs in response to flooding may be basal within the group, but amphibian lineages in tropical Asia and sub-Saharan Africa have not received as much attention as their Neotropical counterparts. We investigated submergence-induced hatching in Feihyla hansenae, a Rhacophorid tree frog with terrestrial eggs. We quantified natural rates of clutch submergence at our study site in Thailand. Using submergence experiments, we found that embryos are capable of hatching early to escape flooding, and that failure to hatch results in mortality. Among the embryos that were able to hatch early, only the earliest, youngest hatchlings experienced a trade-off in body size that persisted for 6 days, while later, older hatchlings were not significantly smaller than spontaneous hatchlings under control conditions. By incorporating our natural and experimental data into Monte Carlo methods to simulate and compare survival probabilities with and without hatching plasticity, we found an overall 3.1% increase in submergence survival due to hatching plasticity. Our findings support the idea that flooding-induced hatching is widespread across amphibians with terrestrial eggs and highlight the importance of researching understudied tropical regions. As climate change is projected to affect rainfall patterns, the ability of embryos to escape abiotic egg-stage threats may be an indicator of species' ability to flexibly navigate a changing environment.     

Antiproliferative Potential of Olneya tesota PF2 Lectin in Human Acute Monocytic Leukemia Cells

Acute monocytic leukemia is a type of myeloid leukemia that develops in monocytes. The current clinical therapies for leukemia are unsatisfactory due to their side effects and nonspecificity toward target cells. Some lectins display antitumor activity and may specifically recognize cancer cells by binding to carbohydrate structures on their surface. Therefore, this study evaluated the response of the human monocytic leukemia cell lines THP-1 to the Olneya tesota PF2 lectin. The induction of apoptosis and reactive oxygen species production in PF2-treated cells was evaluated by flow cytometry, and the lectin-THP-1 cell interaction and mitochondrial membrane potential were evaluated by confocal fluorescence microscopy. PF2 genotoxicity was evaluated by DNA fragmentation analysis via gel electrophoresis. The results showed that PF2 binds to THP-1 cells, triggers apoptosis and DNA degradation, changes the mitochondrial membrane potential, and increases reactive oxygen species levels in PF2-treated THP-1 cells. These results suggest the potential use of PF2 for developing alternative anticancer treatments with enhanced specificity.     

Synergistic interactions between XPC and p53 mutations in double-mutant mice: neural tube abnormalities and accelerated UV radiation-induced skin cancer

The significance of DNA repair to human health has been well documented by studies on xeroderma pigmentosum (XP) patients, who suffer a dramatically increased risk of cancer in sun-exposed areas of their skin [1] and [2]. This autosomal recessive disorder has been directly associated with a defect in nucleotide excision–repair (NER) [1] and [2]. Like human XP individuals, mice carrying homozygous mutations in XP genes manifest a predisposition to skin carcinogenesis following exposure to ultraviolet (UV) radiation [3], [4] and [5]. Recent studies have suggested that, in addition to roles in apoptosis [6] and cell-cycle checkpoint control [7] in response to DNA damage, p53 protein may modulate NER [8]. Mutations in the p53 gene have been observed in 50% of all human tumors [9] and have been implicated in both the early [10] and late [11] stages of skin cancer. To examine the consequences of a combined deficiency of the XPC and the p53 proteins in mice, we generated double-mutant animals. We document a spectrum of neural tube defects in XPC p53 mutant embryos. Additionally, we show that, following exposure to UV-B radiation, XPC p53 mutant mice have more severe solar keratosis and suffer accelerated skin cancer compared with XPC mutant mice that are wild-type with respect to p53.     

A simple cell labeling technique by means of lectins linked to fluorochromes for the detection of cells on tissue sections

Summary— We designed a protocol for cell labeling with the lectin wheat germ agglutinin (WGA) linked to the fluorochrome tetramethyl-rhodamine isothiocyanate (TRITC) for effective detection of the B16F10 melanoma and Lewis lung carcinoma (LLc) cells on pulmonary histological sections from C57BL6; mice. We have also determined a suitable concentration of WGA-TRITC (10 μg/ml), which leads to a very intense and homogeneous labeling of the cells, as it avoids cell clumping due to the presence of the lectin WGA. In order to determine to what extent the method affects these tumor cells, we have studied some important aspects related to their metastatic behavior, taking into account three parameters: a) viability and rate of proliferation of the cells cultured in vitro; b) percentage of animals C57BL6 mice) bearing metastasis 15 days after intravenous inoculation with 10⁵ B16F10 or LLc cells; and c) pattern of distribution of tumor foci in lung. There were no significant differences in these three parameters between the WGA-TRITC labeled-cells compared to the cultures of non-labeled cells in either of the cell lines (B16F10, LLc). Thus, we conclude that B16F10 and LLc tumor cells can be labeled following the protocol set-up in our study, as it allows these cells to be neatly identified on tissue sections and it causes no important physiological changes in the cells, with regard to metastatic behavior. These points make this technique very suitable for the detection of B16F10 and LLc cells on histological sections in studying their behavior during the first stages of the metastatic process.