CHROMOSOME MUTATIONS IN A FERN POPULATION GROWING IN A POLLUTED ENVIRONMENT: A BIOASSAY FOR MUTAGENS IN AQUATIC ENVIRONMENTS

A population of royal ferns, Osmunda regalis, which is periodically submersed by the waters of the Millers River was found to have a very high frequency of chromosome mutations. The Millers River is located in western Massachusetts and is heavily polluted with industrial wastes. Approximately 43 % of meiotic samples collected in 1973 from the Millers River population were heterozygous for mutations such as paracentric inversions or reciprocal translocations, whereas less than 1 % of meiotic samples from nearby non-polluted control populations were such heterozygotes. Cytological analysis within royal fern clones indicate that practically all of the chromosome mutations were post-zygotically induced and that at least 64 % were induced since 1969. In the course of this study over 26,000 spore mother cells were analyzed for chromosome aberrations.     

MUTATIONAL LOAD IN A FERN POPULATION GROWING IN A POLLUTED ENVIRONMENT

The Osmunda regalis sporophyte is well organized for the storage and perpetuation of post-zygotic mutations. Techniques have been developed to detect sporophytes in which such mutations have occurred. Two populations were screened for sporophytes which are chimeras for gametophytic or recessive sporophytic lethals. The populations had different ecologies; one was in a pristine lake side bog and the other was growing in the waters of a river heavily polluted with industrial wastes. Post-zygotic mutations were detected only in the polluted river population. The level of mutational damage approximated that previously documented from chromosome studies.     

A MASTER CLASS IN UNDERSTANDING VARIATIONS IN HEALTHCARE

That there is wide-spread variation in healthcare outcomes cannot be denied. The question is what does the variation mean and what can we do about it? Using a series of well-known case-studies, which include data from the Bristol and Shipman Inquiries, fundamental limitations of traditional methods of understanding variation will be highlighted. These methods, which include comparison with standards, league tables and statistical testing, have flaws and they offer little or no guidance on how to re-act to the variation. Fortunately, there is a theory of variation that overcomes these limitations and provides useful guidance on re-acting to variation, which was developed by Walter Shewhart in the 1920s in an industrial setting. Shewhart's theory of variation found widespread application and won him the accolade 'Father of modern quality control'. His work is central to philosophies of continual improvement. Application of Shewhart's theory of variation, also known as Statistical Process Control (SPC), to case-studies from healthcare will be demonstrated, whilst highlighting the implications and challenges for performance management/monitoring and continual improvement in the healthcare.
References:  1. M A Mohammed, KK Cheng, A Rouse, T Marshall. "Bristol, Shipman and clinical governance: Shewhart's forgotten lessons" The Lancet 2001; 357: 463–7.
2. P Adab, A Rouse, M A Mohammed, T Marshall. "Performance league tables: the NHS deserves better" British Medical Journal 2002; 324: 95–98     

DIVERGENCE IN SYMBIOTIC COMPATIBILITY IN A LEGUME-BRADYRHIZOBIUM MUTUALISM

Geographic variation in the mutualism between the legume Amphicarpaea bracteata and its nitrogen-fixing root nodule bacteria (Bradyrhizobium sp.) was analyzed by sampling genotypes from 11 sites separated by distances ranging from 0.6 km to more than 1000 km. Cross inoculation experiments revealed that plants were genetically differentiated in traits determining compatibility with mutualist partners from different sites. Combinations of plant and bacterial genotypes native to the same local habitat yielded 26% higher plant growth relative to non-native combinations (range across 4 experiments; 9% to 48%). Among non-native symbioses, plant growth was unrelated to the geographic distance between sites of plant and bacterial origin. However, compatibility varied significantly with the genetic distance among host populations (inferred by multilocus enzyme electrophoresis): genetically similar plants from separate sites showed superior growth with each other's mutualist partners. Nevertheless, the tree structure of population genetic similarity was not congruent in plants versus bacteria. This implies that adaptive variation in symbiotic compatibility has evolved without strictly parallel divergence in the two species.     

CO-ORDINATION IN A SCYPHISTOMA

The scyphistoma of Amelia unrila was stimulated electricallyand mechanically in various well defined regions. Each of theseregions is neurologically independent in that the effects ofthe stimulation are localized to just one region of the polyp.Co-ordination of the different regions during prey capture andingestion is still possible however because of the arrangementof the parts of the polyp in which one action sets off anotherone mechanically. The polypoid form of the scyphistoma is ageometrical arrangement allowing mechanical co-ordination. Sucha co-ordination mechanism would not be suitable for the lifeof a medusa whose complicated problems necessitate neurologicalconnections between the body regions for their co-ordination.On the principle that simple organisms arose first during evolution,it is maintained that the polypoid preceded the medusoid formin the Class Scyphozoa. Of the three polypoid types viz. hydropolyp,scyphopolyp and anthopolyp, the scyphopolyp has the simplestneuromuscular system and behavior.     

SEA OTTER DIETS IN A DECLINING POPULATION IN ALASKA

Diet of sea otters ( Enhydra lutris ) using a haulout site on the north side of the Alaska Peninsula was determined from 50 scats. Dominant prey species were mussels ( Mytilus edulis ), followed by three species of clams ( Siliqua spp., Spisula polynyma , and Tellina lutea ), sand dollars ( Echinarachnius parma ), and helmet crabs ( Telmessus cheiragonus ). Our results support preliminary findings by Cim-berg et al. (1984) that this sea otter population preys heavily on mussels and that the presence of low caloric value sand dollars in their diet is significant. Coupled with population estimates, our results also provide evidence that this population of sea otters may be declining due, in part, to overdepletion of food resources.