Cys-92, Cys-95, and the C-terminal 12 residues of the Vibrio harveyi ferric uptake regulator (Fur) are functionally inessential

Ferric uptake regulator (Fur) is a global regulator involved in multiple aspects of bacterial life. The gene encoding the Vibrio harveyi Fur (Fur(vh)) was cloned from a pathogenic V. harveyi strain isolated from diseased fish. Furvh shares 77% overall sequence identity with the Escherichia coli Fur (Fur(Ec)) and could complement a mutant of Fur(Ec). Like Fur(Ec), Fur(Vh), possesses two cysteine residues at positions 92 and 95, yet unlike Fur(Ec), in which these cysteine residues constitute part of the metal ion coordination site and hence are vital to the repressor activity, C92 and C95 of Fur(Vh) proved to be functionally inessential. Further study identified a Vibrio Fur signature sequence, which is preserved in all the ten Vibrio Fur proteins that have been discovered to date but in none of the non-vibrio Fur proteins. Site-directed and random mutation analyses of the signature residues, the cysteine residues, and seven highly charged amino acid residues indicated that D9, H32, C137, and K138 of Fur(vh) are functionally important but D9, C137, and K138 can be replaced by more than one functional substitutes. Systematic deletion analysis demonstrated that the C-terminal 12 residues of Fur(Vh) are functionally inessential. These results (i) indicated that the activation mechanism, or certain aspects of which, of Fur(Vh) is possibly different from that of Fur(Ec); and (ii) suggested that it is not very likely that the C-terminal 12 residues play any significant role in the activation or stability of Fur(Vh); and (iii) provided insights into the potential function of the local structure involving C137 and K138.

Molecular analysis of the fur (ferric uptake regulator) gene of a pathogenic Edwardsiella tarda strain

The gene encoding the Edwardsiella tarda ferric uptake regulator (Fur(Et)) was cloned from a pathogenic E. tarda strain isolated from diseased fish. Fur(Et) shares 90% overall sequence identity with the Escherichia coli Fur (Fur(Ec)) and was able to complement the mutant phenotype of a fur(Ec)-defective E. coli strain. Mutational analysis indicated that C92S and C95S mutations inactivated Fur(Et) whereas E112K mutation resulted in a superactive Fur(Et) variant. Fur(Et) negatively regulated its own expression; interruption of this regulation impaired bacterial growth, altered the production of certain outer membrane proteins, and attenuated bacterial virulence.

The Impact of Offshore Wind Farms on Marine Ecosystems: A Review Taking an Ecosystem Services Perspective

The rapid increase in renewable energy generation from wind has increased concerns about the impacts that wind arrays have on the marine environment and what these impacts mean for society. One method for identifying the impacts of offshore wind farms (OWFs) on human welfare is through the assessment and valuation of ecosystem services. Using an ecosystem services approach, this paper reviews the impacts of OWFs on the ecosystem services delivered by marine environments. During the construction phase, supporting services such as reduced energy capture and nutrient cycling are changed due to the introduction of hard substrate and the reduction in soft sediment habitat at turbine bases. This may lead to changes in all other ecosystem services, both negative and positive. Quantifying these changes, however, is a challenge partly due to data limitations and a lack of clear understanding of the impacts of OWFs on the marine ecosystems. Scientific effort needs to quantitatively explore the impacts of OWFs on ecosystem functionality and the gathering of data that enables the assessment of changes to ecosystem services. Data needed to better quantify and value the impacts of OWFs on ecosystem services are suggested. The development of methods which integrate socioeconomic valuation of ecosystem services into the evaluation of renewable energy devices compliments efforts in assessing the environmental impacts and should enable a holistic assessment of the impact of renewable energy production and greenhouse gas mitigation technologies on the U. K. carbon footprint.

Dendrochronology and Deer Park Farms

This chapter examines some aspects of the environmental
context for the constructional activity observed at Deer
Park Farms (DPF). This can be done at several levels by
observing what dendrochronology suggests in terms of
environment and environmental change across the period
from around AD 500 to 1000. Looking at the broad sweep
of tree growth across the period, something not previously
attempted, we can make comparisons between tree
growth in Ireland and elsewhere in Europe. We can study
abrupt events in the records and draw on information
from other sources in an attempt to paint a picture of the
period against which to view the constructional activity
on the site itself. It is worth remarking that there is no
blueprint for this work. Most of the information used has
only recently been produced and it is largely independent
of conventional history.

Coordinated Control of DFIG and FSIG-based Wind Farms under Unbalanced Grid Conditions

This paper investigates the control and operation of doubly-fed induction generator (DFIG) and fixed-speed induction generator (FSIG) based wind farms under unbalanced grid conditions. A DFIG system model suitable for analyzing unbalanced operation is developed, and used to assess the impact of an unbalanced supply on DFIG and FSIG operation. Unbalanced voltage at DFIG and FSIG terminals can cause unequal heating on the stator windings, extra mechanical stresses and output power fluctuations. These problems are particularly serious for the FSIG-based wind farm without a power electronic interface to the grid. To improve the stability of a wind energy system containing both DFIG and FSIG based wind farms during network unbalance, a control strategy of unbalanced voltage compensation by the DFIG systems is proposed. The DFIG system compensation ability and the impact of transmission network impedance are illustrated. The simulation results implemented in Matlab/Simulink show that the proposed DFIG control system improves not only its own performance, but also the stability of the FSIG system with the same grid connection point during network unbalance.

Parish farms and the poor law: a response to unemployment in rural southern England, c.1815-1835

Finding a ‘solution’ for the seemingly intractable problem of unemployment in post-Napoleonic rural England was the Holy Grail for many vestries. Yet, whilst we know much about the depth and consequences of unemployment, parish-driven schemes to set the poor to work have been subjected to remarkably little in the way of systematic study. This paper focuses on one such policy that remains entirely obscure: parish farms, the hiring of pre-existing farms or fields by the parish on which to employ those out of work. Bearing a ‘family resemblance’ to allotments and other land-based attempts to alleviate poverty, parish farms were unique in that they were managed in all regards by the parish and were an employment strategy as opposed to a scheme to supplement the incomes of the poor. Whilst the archive of parish farms is often frustratingly opaque, it is shown that before they were effectively outlawed by the passing of the New Poor Law, many southern parishes, especially in the Weald of Kent and Sussex, adopted the scheme, occasionally with great success.

Temporal distribution of porcine circovirus 2 genogroups recovered from postweaning multisystemic wasting syndrome-affected and -nonaffected farms in Ireland and Northern Ireland

Porcine circovirus type 2 (PCV2) is now recognized as the essential infectious component of porcine postweaning multisystemic wasting syndrome (PMWS). PMWS was first recognized in high-status, specific pathogen-free pigs in Canada in 1991 and is now an economically important disease that affects the swine industry around the world. Recently, reports of genomic studies on PCV2 viruses indicated that 2 distinctive genogroups of PCV2 exist.(4,10) This report involves the results of a study on the distribution of predominant PCV2 genogroups recovered from samples taken from PMWS-affected and PMWS-nonaffected farms on the island of Ireland over a 9-year period and the results of a study on PCV2 genogroup recovery from fecal samples taken from a farm in Northern Ireland from 2003 to 2005 that was first diagnosed as PMWS positive in August 2005. The results indicate that, although at least 2 distinct genogroups of PCV2 have been circulating on pig farms on the island of Ireland, there does not appear to be a direct relationship between infection with these different genogroups of PCV2 and the development of PMWS.