Influence of sexual dimorphism and dichromatism on reproductive success in a rare native cactus.

Identifying plant sexual dimorphic traits is critical in advancing our knowledge on plant-pollinator interactions. For example, dimorphism in floral colors, or sexual dichromatism, is a crucial mediator of pollinator choice on foraging decisions. We studied Cylindropuntia wolfii, a model system, with diverse flower colors and a functionally dioecious sexual system. However, evidence suggests that sexual reproduction is limited in this species as it has a low seed set especially in naturally pollinated fruits. Thus, it is critical to this native species' conservation to investigate its relationship with pollinators. Our goals were to: (a) investigate the sexual dimorphism including the sexual dichromatism in the flowers of the cactus, and (b) determine whether sexually dimorphic traits affect the pollinator attraction of both the sexes. We measured several quantitative and qualitative traits and compared them between male and female flowers. Then we recorded the pollinator visitation rate in nature for both sexes and tracked pollinator color preference using fluorescent dyes as pollen analogues. Our study showed that male flowers of C. wolfii are bigger and brighter, and they attract more potential pollinators than females, supporting the hypothesis that sexual dimorphism influences pollinator visitation preference. Fluorescence dichromatism, in which female flowers' anthers fluoresce more than male flower anthers suggest this could be female flowers' strategy to compensate for their dark colors and small size. The results from this study showed that C. wolfii exhibits sexual dichromatism and fluorescence dichromatism, which is a novel finding in plant research.

Unraveling the development behind unisexual flowers in Cylindropuntia wolfii (Cactaceae).

BACKGROUND: In certain unisexual flowers, non-functional sexual organs remain vestigial and unisexuality can be overlooked leading to the ambiguous description of the sexual systems. Therefore, to accurately describe the sexual system, detailed morphological and developmental analyses along with experimental crosses must be performed. Cylindropuntia wolfii is a rare cactus endemic to the Sonoran Desert in southern California and northern Baja California that was described as gynodioecious by morphological analysis. The aims of our project include accurately identifying the sexual system of C. wolfii using histological and functional studies and characterizing the developmental mechanisms that underlie its floral development. METHODS: Histological analyses were carried out on different stages of C. wolfii flowers and controlled crosses were performed in the field. RESULT: Our results identified C. wolfii to be functionally dioecious. The ovule and anther development differed between staminate and pistillate flowers. In vivo pollen germination tests showed that the pollen of staminate and pistillate flowers were viable and the stigma and style of both staminate and pistillate flowers were receptive. This suggests that there are no genetic or developmental barriers in the earlier stages of pollen recognition and pollen germination. CONCLUSIONS: Despite being functionally dioecious, we observed that functionally pistillate individuals produced fruits with a large number of aborted seeds. This implies that not only does this species have low reproductive success, but its small population sizes may lead to low genetic diversity.

Major biogeographic barriers in eastern Australia have shaped the population structure of widely distributed Eucalyptus moluccana and its putative subspecies.

We have investigated the impact of recognized biogeographic barriers on genetic differentiation of grey box (Eucalyptus moluccana), a common and widespread tree species of the family Myrtaceae in eastern Australian woodlands, and its previously proposed four subspecies moluccana, pedicellata, queenslandica, and crassifolia. A range of phylogeographic analyses were conducted to examine the population genetic differentiation and subspecies genetic structure in E. moluccana in relation to biogeographic barriers. Slow evolving markers uncovering long term processes (chloroplast DNA) were used to generate a haplotype network and infer phylogeographic barriers. Additionally, fast evolving, hypervariable markers (microsatellites) were used to estimate demographic processes and genetic structure among five geographic regions (29 populations) across the entire distribution of E. moluccana. Morphological features of seedlings, such as leaf and stem traits, were assessed to evaluate population clusters and test differentiation of the putative subspecies. Haplotype network analysis revealed twenty chloroplast haplotypes with a main haplotype in a central position shared by individuals belonging to the regions containing the four putative subspecies. Microsatellite analysis detected the genetic structure between Queensland (QLD) and New South Wales (NSW) populations, consistent with the McPherson Range barrier, an east-west spur of the Great Dividing Range. The substructure was detected within QLD and NSW in line with other barriers in eastern Australia. The morphological analyses supported differentiation between QLD and NSW populations, with no difference within QLD, yet some differentiation within NSW populations. Our molecular and morphological analyses provide evidence that several geographic barriers in eastern Australia, including the Burdekin Gap and the McPherson Range have contributed to the genetic structure of E. moluccana. Genetic differentiation among E. moluccana populations supports the recognition of some but not all the four previously proposed subspecies, with crassifolia being the most differentiated.

Heterogeneity of Small Cell Lung Cancer Stem Cells.

Small cell lung cancer, a subtype of lung cancer is an extremely malignant disease due to its metastases and recurrence. Patients with SCLC develop resistance to chemotherapy and the disease relapses. This relapse and resistance are attributed to the heterogeneity of SCLC. Various factors such as recurrent mutations in key regulatory genes such as TP53, RB1, and myc, epigenetic changes, and cancer stem cells contribute to the observed heterogeneity. Cancer stem cell models predict neuroendocrine origin of SCLC. Though an unambiguous established CSC marker has not been assigned, markers CD133, CD44 have been found associated with SCLC. Genetically engineered mouse models (GEMMs) allow the validation of driver mutations and are necessary for design of targeted therapy. This chapter outlines the factors contributing to SCLC heterogeneity, detection methods, and the current therapy trials.

Functional characterization of 1-aminocyclopropane-1-carboxylic acid oxidase gene in Arabidopsis thaliana and its potential in providing flood tolerance.

Ethylene is a phytohormone that has gained importance through its role in stress tolerance and fruit ripening. In our study we evaluated the functional potential of the enzyme involved in ethylene biosynthesis of plants called ACC (aminocyclopropane-1-carboxylic acid) oxidase which converts precursor ACC to ethylene. Studies on ethylene have proven that it is effective in improving the flood tolerance in plants. Thus our goal was to understand the potential of ACC oxidase gene overexpression in providing flood tolerance in transgenic plants. ACC oxidase gene was PCR amplified and inserted into the pBINmgfp5-er vector, under the control of a constitutive Cauliflower Mosaic Virus promoter. GV101 strain of Agrobacterium tumefaciens containing recombinant pBINmgfp5-er vector (referred herein as pBIN-ACC) was used for plant transformation by the 'floral dip' method. The transformants were identified through kanamycin selection and grown till T3 (third transgenic) generation. The flood tolerance was assessed by placing both control and transgenic plants on deep plastic trays filled with tap water that covered the soil surface. Our result shows that wild-type Arabidopsis could not survive more than 20 days under flooding while the transgenic lines survived 35 days, suggesting development of flood tolerance with overexpression of ACC oxidase. Further molecular studies should be done to elucidate the role and pathways of ACC oxidase and other phytohormones involved in the development of flood adaptation.

Lung cancer stem cells-origin, characteristics and therapy.

Cancer stem cells (CSCs) have gained an increasing attention recently in cancer research. CSCs have ability to generate new tumor through their stem cell properties, essentially self-renewal potential and differentiation into multiple cell lineages. Extensive evidences report that CSCs are resistant to many conventional therapies and mediate tumor recurrence. CSCs of lung cancer are well recognized by their specific markers such as CD133, CD44, ABCG2 and ALDH1A1 together with the CSC characteristics including spheroid and colony formation. Targeting these surface proteins with blocking antibodies and inhibition of ABC transporters and aldehyde dehydrogenase (ALDH) enzymes with small molecules may prove useful in inhibiting tumor progression. The Hh, Notch and Wnt pathways are key signaling cascades that govern cell fate during development and have been shown to be involved in CSCs in various solid tumors. Therapeutic approaches also target these signaling pathways in repressing the tumor progression. This review will focus on stem cell origins, role of signaling pathways, stem cell markers and therapeutic approaches specific to lung cancer.

Extraction of RNA from Recalcitrant Tree Species Paulownia elongata.

Isolation of pure RNA is the basic requisite for most molecular biology work. Plants contain polyphenols and polysaccharides, which can interfere with isolation of pure RNA from them. Especially hardwood tree species like Paulownia elongata have surplus amount of RNA-binding alkaloids, proteins and secondary metabolites that can further complicate the process of RNA extraction. Paulownia elongata is a fast-growing tree species which is known for its role in environmental adaptability and biofuel research. Here we describe an economical, efficient and time-saving method (2 h) to extract RNA from leaf tissues of the tree Paulownia elongata. Lack of DNA contamination and good RNA integrity were confirmed using RNA Gel electrophoresis. The purity of RNA was confirmed using Nanodrop spectrophotometer that revealed an A260:A280 ratio of about 2.0. The purified RNA was successfully used in the downstream applications such as RT-PCR (Reverse Transcription PCR) and qPCR (quantitative PCR). This method could be used for RNA extraction from several other recalcitrant tree species.