Transgene flow to hybrid rice and its male-sterile lines

Gene flow from genetically modified (GM) crops to the same species or wild relatives is a major concern in risk assessment. Transgenic rice with insect and/or disease resistance, herbicide, salt and/or drought tolerance and improved quality has been successfully developed. However, data on rice gene flow from environmental risk assessment studies are currently insufficient for the large-scale commercialization of GM rice. We have provided data on the gene flow frequency at 17 distances between a GM japonica line containing the bar gene as a pollen donor and two indica hybrid rice varieties and four male-sterile (ms) lines. The GM line was planted in a 640m² in an isolated experimental plot (2.4 ha), which simulates actual conditions of rice production with pollen competition. Results showed that: (1) under parallel plantation at the 0-m zone, the transgene flow frequency to the ms lines ranged from 3.145 to 36.116% and was significantly higher than that to hybrid rice cultivars (0.037–0.045%). (2) Gene flow frequency decreased as the distance increased, with a sharp cutoff point at about 1–2 m; (3) The maximum distance of transgene flow was 30–40 m to rice cultivars and 40–150 m to ms lines. We believe that these data will be useful for the risk assessment and management of transgenic rice lines, especially in Asia where 90% of world's rice is produced and hybrid rice varieties are extensively used. Shirong Jia, Feng Wang and Lei Shi contributed equally to this investigation.     

Mountain cheese factory wastewater treatment with the use of a hybrid constructed wetland

This paper describes the activity period of an experimental hybrid wetland system placed in a cold climate region. The aim is to determine the efficiency of the system in reducing TSS, BOD₅, COD and other pollutants. The constructed wetland consists of a fat-removal unit and a basin for the storage and the distribution of the wastewater which precedes three phytoremediation beds: the first two are parallel and they work as submerged vertical flow wetland with gravel medium for an area of 180 m²; the last is a submerged horizontal flow wetland with sand medium and an area of 360 m². The CW was designed to process a total estimated BOD₅ loading rate of about 24 g m⁻² d⁻¹, which was less than half of the average actual loading rate. The wastewater treatment did not meet the required Italian law outflow limits, most likely due to BOD₅ overloading.     

An evolutionary hybrid cellular automaton model of solid tumour growth

We propose a cellular automaton model of solid tumour growth, in which each cell is equipped with a micro-environment response network. This network is modelled using a feed-forward artificial neural network, that takes environmental variables as an input and from these determines the cellular behaviour as the output. The response of the network is determined by connection weights and thresholds in the network, which are subject to mutations when the cells divide. As both available space and nutrients are limited resources for the tumour, this gives rise to clonal evolution where only the fittest cells survive. Using this approach we have investigated the impact of the tissue oxygen concentration on the growth and evolutionary dynamics of the tumour. The results show that the oxygen concentration affects the selection pressure, cell population diversity and morphology of the tumour. A low oxygen concentration in the tissue gives rise to a tumour with a fingered morphology that contains aggressive phenotypes with a small apoptotic potential, while a high oxygen concentration in the tissue gives rise to a tumour with a round morphology containing less evolved phenotypes. The tissue oxygen concentration thus affects the tumour at both the morphological level and on the phenotype level.     

Assortative mating across a hybrid zone in Chorthippus parallelus (Orthoptera: Acrididae)

Two subspecies of the grasshopper Chorthippus parallelus meet and form a hybrid zone in the Pyrenees. Both strong hybrid dysfunction and a behavioural difference occur, which would seem to make the zone a suitable candidate for speciation by reinforcement. One of the classic ways of looking for this is to test for increased levels of assortative mating between populations from close to the region of contact. Here we show that, with virgin insects, such assortment decreases as one approaches the centre of the zone in C. parallelus. The pattern is different upon remating, with non-virgins showing a pattern more like that predicted by reinforcement. Overall there is little evidence for reinforcement. We argue that other tests of the model may be more appropriate for stable hybrid zones.     

Molecular evidence of a reed warbler × great reed warbler hybrid ( Acrocephalus scirpaceus × A. arundinaceus) in Belgium

We report on the second case of a reed warbler × great reed warbler hybrid (Acrocephalus scirpaceus and A. arundinaceus). The bird was captured during a standardised ringing session in Belgium in autumn 1999, and fell between the parental species in all measurements. Molecular analyses of two microsatellite loci verified that the bird was a female that had a reed warbler father and a great reed warbler mother.     

Characteristics of hamadryas-like male baboons living in anubis baboon troops in the Awash hybrid zone, Ethiopia.

In the twenty-two years since the Awash baboon hybrid zone was first described, about 25-30 hamadryas or hamadryas-like hybrid males have taken up residence in anubis baboon groups. Most enter as mature adults, though some may immigrate as juvenile followers. Long-term tracking of known immigrants indicates that they may reside for four years or more in their adopted troop, during which time they establish a series of comparatively short-term harems, and probably sire hybrid offspring. "Abductions" of anubis females to hamadryas troops, as postulated by early observers, were not seen, though their occurrence cannot be ruled out. Younger, more recent immigrants tend to be "purer" hamadryas in phenotype, perhaps reflecting a more distant origin, or a change in the composition of neighboring hamadryas populations. Coexisting hamadryas and anubis show no signs of reproductive isolation by behavioral barriers, and evidently belong to a single "recognition species."     

Synthesis of Ester-Linked Ursolic Acid-Based Hybrid Compounds: Potential Antibacterial and Anticancer Agents

The molecular hybridization of two or more drugs into a single molecule is an effective drug design approach to reduce pill burden and improve patient treatment adherence. Ursolic acid-based hybrid compounds were synthesized and characterized followed by molecular docking studies. In vitro studies against various bacterial strains and human cancer cells (MDA-MB-231, HeLa, and MCF-7) were performed. Compounds 14 – 19 , 21 , 34 , 31 , and 30 demonstrated significant antibacterial activities with MIC values of 15.625 μg/ml. Compounds 29 and 34 were more cytotoxic than ursolic acid, with IC₅₀ values of 46.99 and 48.18 μg/ml. Compounds 29 and 34 in the docking studies presented favourable binding interactions and better docking energy against the Epidermal Growth Factor Receptor (EGFR) than the parent compound, ursolic acid. The findings revealed that the ursolic acid scaffold is a promising precursor for the development of molecules with promising anticancer and antimicrobial activities. However, more studies are needed to fully understand their mode of action.     

Polyketide-nonribosomal peptide epothilone antitumor agents: the EpoA,B, C subunits

The epothilones are a family of macrolactone natural products from the myxobacterial species Sorangium cellulosum. Similar to taxol, they are of current clinical interest as anticancer agents. Sequence analysis of the epothilone gene cluster allowed the identification of polyketide synthase and nonribosomal peptide synthetase modules involved in catalyzing epothilone biosynthesis. Given this information, it has been possible to test the predicted functions of several modules to date. EpoA ACP, EpoB, and EpoC have been overproduced in Escherichia coli, allowing in vitro reconstitution of the EpoA/B/C interface and production of the expected epothilone precursor. Further experiments probed the tolerance of EpoB and EpoC for unnatural substrates. These studies of the first three modules of the epothilone biosynthetic cluster suggest that combinatorial biosynthesis may lead to the production of a variety of epothilone analogs that incorporate diversity into the heterocycle starter unit. Additional efforts with the remaining modules, coupled with increased understanding of the macrocyclizing thioesterase domain, may lead to the production of epothilone variants with improved clinical properties.