Determination of the Settling Rate of Clay/Cyanobacterial Floccules.

The mechanisms underpinning the deposition of fine-grained, organic-rich sediments are still largely debated. Specifically, the impact of the interaction of clay particles with reactive, planktonic cyanobacterial cells to the sedimentary record is under studied. This interaction is a potentially major contributor to shale depositional models. Within a lab setting, the flocculation and sedimentation rates of these materials can be examined and measured in a controlled environment. Here, we detail a protocol for measuring the sedimentation rate of cyanobacterial/clay mixtures. This methodology is demonstrated through the description of two sample experiments: the first uses kaolin (a dehydrated form of kaolinite) and Synechococcus sp. PCC 7002 (a marine coccoid cyanobacteria), and the second uses kaolin and Synechocystis sp. PCC 6803 (a freshwater coccoid cyanobacteria). Cyanobacterial cultures are mixed with varying amounts of clay within a specially designed tank apparatus optimized to allow continuous, real-time video and photographic recording. The sampling procedures are detailed as well as a post-collection protocol for precise measurement of chlorophyll a from which the concentration of cyanobacterial cells remaining in suspension can be determined. Through experimental replication, a profile is constructed that displays sedimentation rate.

Sensory and Behavioral Responses of a Model Fish to Oil Sands Process-Affected Water with and without Treatment.

If oil sands process-affected water (OSPW) is to be returned to the environment, a desire is that it not adversely affect aquatic life. We investigated whether a relevant model fish (rainbow trout, Oncorhynchus mykiss) could detect OSPW using its olfactory sense (smell) and whether exposure to it would result in behavioral changes. We also investigated whether ozonation of OSPW, which lowers the concentration of organic compounds attributed with toxicity (naphthenic acids), would ameliorate any observed adverse effects. We found that OSPW, regardless of ozonation, evoked olfactory tissue responses similar to those expected of natural odorants, suggesting that fish could smell OSPW. In 30 min OSPW exposures, olfactory responses to a food odorant and a pheromone were reduced to a similar degree by OSPW, again regardless of ozonation. However, olfactory responses returned within minutes of exposure cessation. In contrast, in longer (7 d) exposures, olfactory responses remained impaired, but not in fish that had received ozone-treated OSPW. In the behavioral assay, fish avoided an introduced plume of OSPW, and this response was not affected by ozonation. Taken together, our data suggest that fish smell OSPW, that they may use this sense to mount an avoidance response, and that, if they cannot avoid it, their sensory responses may be impaired, unless the OSPW has received some remediation.

Trans-specific S-RNase and SFB alleles in Prunus self-incompatibility haplotypes.

Self-incompatibility in the genus Prunus is controlled by two genes at the S-locus, S-RNase and SFB. Both genes exhibit the high polymorphism and high sequence diversity characteristic of plant self-incompatibility systems. Deduced polypeptide sequences of three myrobalan and three domestic plum S-RNases showed over 97% identity with S-RNases from other Prunus species, including almond, sweet cherry, Japanese apricot and Japanese plum. The second intron, which is generally highly polymorphic between alleles was also remarkably well conserved within these S-allele pairs. Degenerate consensus primers were developed and used to amplify and sequence the co-adapted polymorphic SFB alleles. Sequence comparisons also indicated high degrees of polypeptide sequence identity between three myrobalan and the three domestic plum SFB alleles and the corresponding Prunus SFB alleles. We discuss these trans-specific allele identities in terms of S-allele function, evolution of new allele specificities and Prunus taxonomy and speciation.

Self-(in)compatibility of the almonds P. dulcis and P. webbii: detection and cloning of 'wild-type Sf ' and new self-compatibility alleles encoding inactive S-RNases.

Prunus dulcis, the almond, is a predominantly self-incompatible (SI) species with a gametophytic self-incompatibility system mediated by S-RNases. The economically important allele Sf, which results in self-compatibility in P. dulcis, is said to have arisen by introgression from Prunus webbii in the Italian region of Apulia. We investigated the range of self-(in)compatibility alleles in Apulian material of the two species. About 23 cultivars of P. dulcis (14 self-compatible (SC) and nine SI) and 33 accessions of P. webbii (16 SC, two SI and 15 initially of unknown status), all from Apulia, were analysed using PCR of genomic DNA to amplify S-RNase alleles and, in most cases, IEF and staining of stylar protein extracts to detect S-RNase activity. Some amplification products were cloned and sequenced. The allele Sf was present in nearly all the SC cultivars of P. dulcis but, surprisingly, was absent from nearly all SC accessions of P. webbii. And of particular interest was the presence in many SI cultivars of P. dulcis of a new active allele, labelled S30, the sequence of which showed it to be the wild-type of Sf so that Sf can be regarded as a stylar part mutant S30 degrees . These findings indicate Sf may have arisen within P. dulcis, by mutation. One SC cultivar of P. dulcis, 'Patalina', had a new self-compatibility allele lacking RNase activity, Sn5, which could be useful in breeding programmes. In the accessions of P. webbii, some of which were known to be SC, three new alleles were found which lacked RNase activity but had normal DNA sequences.