Analysis of a backcross population from a multi-copy transgenic Brassica napus line

Brassica napus is one of the crops at the forefront of biotechnological development. The procedures used to produce transgenic varieties are all prone to generating plants with multiple transgene copies. There has been considereable interest in the behaviour of such multi-copy lines because gene dosage rarely appears to correlate simply with gene expression. Here we report the analysis of a population of 107 progeny from a B. napus transformant containing multiple copies of a GUS marker gene construct. A total of 12 GUS sequence copies were identified including one that was non-functional. The expression of GUS increased with increasing copy number but this increase only made up a small proportion of the total variation between lines. There was no evidence of interaction between the various GUS copies and they appeared to segregate independently. The variation between progeny lines indicated that the number of gene copies was not a good guide to the expression of the gene product and hence that the expression of the gene in progeny from a multiple-copy parent could not be predicted. The importance of these findings in relation to plant breeding and the risk assessment process is discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

The genesis and collapse of third millennium north mesopotamian civilization

Archaeological and soil-stratigraphic data define the origin, growth, and collapse of Subir, the third millennium rain-fed agriculture civilization of northern Mesopotamia on the Habur Plains of Syria. At 2200 B. C., a marked increase in aridity and wind circulation, subsequent to a volcanic eruption, induced a considerable degradation of land-use conditions. After four centuries of urban life, this abrupt climatic change evidently caused abandonment of Tell Leilan, regional desertion, and collapse of the Akkadian empire based in southern Mesopotamia. Synchronous collapse in adjacent regions suggests that the impact of the abrupt climatic change was extensive.     

Sperm traits of masculinized fish relative to wild‐type males: a systematic review and meta‐analyses

Environmental sex reversal (ESR), whereby environmental effects (e.g. exogenous chemicals) override genetic sex determination, is a commonly used technique in aquaculture and physiology research. We performed a systematic review and meta‐analyses of the literature that compares the sperm characteristics of masculinized genotypic females to wild‐type males. We detected no mean differences between the ejaculate volume, sperm motility, duration or linearity of each type of male. We found some large mean differences in sperm concentration (d = 2.541, CI = ?0.004 to 5.086), reproductive success (d = ?1.400, CI = ?2.943 to 0.142), semen osmolality (d = 1.850, CI = 0.622 to 3.077) and sperm velocity (d = ?0.933, CI=?1.426 to ?0.441); in the case of the latter two traits, the mean effect was statistically significant. However, any significance did not stand up to a more conservative analysis. Additionally, heterogeneity was high and we found that where large differences between the sperm of sex‐reversed and wild‐type males are reported, these effects are attributable to sperm sampling methodology. Overall, we found little evidence for large systematic differences between the sperm produced by masculinized and wild‐type male fish. Thus, masculinized genotypic females may enjoy reproductive success comparable to genotypic males. This conclusion leads to two potential implications: (i) sex‐reversed fish may influence the dynamics of wild populations and (ii) aquaculture practices may use ESR to produce males with sperm quality similar to that of genotypic males. Most studies appear to have been performed in aquaculture species (i.e. Salmonidae); thus future experiments in non‐model organisms may provide important insights in to the uniformity of the effects described.     

Using T‐PODs to assess variations in the occurrence of coastal bottlenose dolphins and harbour porpoises

• 1. Assessments of anthropogenic impacts on cetaceans are often constrained by limited data on the extent to which these species use particular areas.
• 2. Timing porpoise detectors (T‐PODs) are autonomous data recorders for detecting cetacean echolocation clicks, potentially providing cost‐effective opportunities for monitoring cetacean occurrence.
• 3. The performance of T‐PODs was assessed in three areas off the Scottish east coast, where the relative occurrence of bottlenose dolphins and harbour porpoises was known to differ. Land‐based observations in one area compared visual and acoustic detections of dolphins, while direct hydrophone recordings of dolphin echolocation clicks were compared with T‐POD detections during boat surveys.
• 4. Land‐based surveys recorded 89 groups of dolphins within 900 m of the T‐POD. All groups spending >30 min in the area were detected on the T‐POD, and the probability of detection declined in relation to distance from the recording site.
• 5. The number of dolphin clicks recorded on the independent hydrophone system was significantly related to the number detected by a T‐POD. Between pairs of T‐PODs, there was also significant correlation with the numbers of clicks recorded in each hour, both for channels set to detect bottlenose dolphins and for channels set to detect harbour porpoises.
• 6. Year‐round deployments of paired T‐PODs detected significant geographical variation in detections for both bottlenose dolphins and harbour porpoises. This pattern reflected published data from visual surveys, where dolphins occurred most regularly within the Moray Firth Special Area of Conservation, and porpoises were sighted more regularly in offshore waters.
• 7. T‐PODs do not detect all cetaceans in the area, and care must be taken when interpreting data from mixed species communities. Nevertheless, these results confirm that T‐PODs provide an effective method for monitoring the occurrence of bottlenose dolphins and harbour porpoises, and provide excellent potential for collecting baseline data from poorly studied areas and monitoring long‐term temporal change in key areas of interest. Copyright © 2009 John Wiley & Sons, Ltd.

     

Neurotoxicosis associated with the use of hexachlorophene in a cat

Two weeks after daily topical application of hexachlorophene, a 4-week-old female kitten developed cardiovascular collapse, corneal ulcers, trembling, lethargy, and weakness. The kitten was euthanatized. At necropsy, the tissues appeared macroscopically normal; however, microscopic examination of tissue specimens indicated status spongiosis, astrocytosis, and microgliosis of the cerebral and cerebellar white matter and corticospinal tracts. Neuronal cell bodies forming the affected white matter were intact, indicating that demyelination may have been the cause of the lesions. The neurologic lesions were considered compatible with those of hexachlorophene-induced toxicosis.