T Cell Adaptive Immunity Proceeds through Environment-Induced Adaptation from the Exposure of Cryptic Genetic Variation

Evolution is often characterized as a process involving incremental genetic changes that are slowly discovered and fixed in a population through genetic drift and selection. However, a growing body of evidence is finding that changes in the environment frequently induce adaptations that are much too rapid to occur by an incremental genetic search process. Rapid evolution is hypothesized to be facilitated by mutations present within the population that are silent or “cryptic” within the first environment but are co-opted or “exapted” to the new environment, providing a selective advantage once revealed. Although cryptic mutations have recently been shown to facilitate evolution in RNA enzymes, their role in the evolution of complex phenotypes has not been proven. In support of this wider role, this paper describes an unambiguous relationship between cryptic genetic variation and complex phenotypic responses within the immune system. By reviewing the biology of the adaptive immune system through the lens of evolution, we show that T cell adaptive immunity constitutes an exemplary model system where cryptic alleles drive rapid adaptation of complex traits. In naive T cells, normally cryptic differences in T cell receptor reveal diversity in activation responses when the cellular population is presented with a novel environment during infection. We summarize how the adaptive immune response presents a well studied and appropriate experimental system that can be used to confirm and expand upon theoretical evolutionary models describing how seemingly small and innocuous mutations can drive rapid cellular evolution

Oyster (Crassostrea Virginica, Gmelin 1791) Population Dynamics On Public Reefs In The Great Wicomico River, Virginia, USA

We describe oyster population trends in the Great Wicomico River, VA, from 2000 through 2009 using quantitative fishery independent survey data collected using a stratified random design. The seven public reefs examined cover a total of 2.8 X 10(5) m(2) and vary in individual size from 1.36 X 10(4) to 7.16 X 10(4) m(2). The river is functionally divided by a sand spit into upriver and downriver regions. Oyster densities on the upriver reefs were typically an order of magnitude higher than densities on the downriver reefs within the same time period. Throughout the system, the highest observed densities were coincident with high annual recruitment events (2002, 2006). Recruitment events were usually followed by high mortality, with small percentages of the population reaching \u3e= 3 y of age. A predictive stock recruit relationship is absent; rather, population demographics appear to be dominated by periodic high recruitment events. In the absence of seed removal, biomass maxima follow 1-2 y after recruitment maxima. Standing stock for the system varied between 1.56 X 10(6) g and 3.63 X 10(7) g in 2005 and 2006. Year-specific age-at-length relationships were estimated from demographics data. Length demographics were recast as age demographics to estimate mortality. Observed proportional mortality between young of the year and age 2 oysters was approximately 0.88 for the 2006-y class, which is slightly higher than the 0.62-0.71 observed for the 2007-y class. The ability to estimate age specific mortality accurately allows the construction of shell (habitat) budgets for the individual reef systems. The Great Wicomico oyster population appears to be maintained by episodic and extraordinary recruitment in the face of high mortality the latter driven by disease (predominantly Perkinsus marinus) epizootics. The shell resource is modest, equivalent to little more than a monolayer several centimeters thick. Over short timescales (years), the available shell resource oscillates in concert with mortality. The shell accretion rate on upriver reefs is consistently 4-5 times greater than that observed on downriver reefs. Periodic modest shell planting has maintained the habitat base (the shell resource) throughout the system over decadal scales

Management Of The Piankatank River, Virginia, In Support Of Oyster (Crassostrea Virginica, Gmelin 1791) Fishery Repletion

The Piankatank River is a trap-type estuary on the western shore of Chesapeake Bay that has been managed for seed oyster production since 1963. Market oyster production in the river is minimal. Repletion efforts include shell planting and seed removal. We describe sequential changes in population demographics and habitat in relation to repletion activities on eight Piankatank River public oyster reefs from 1998 through 2009. Two reef groups (northern and southern) may be distinguished by density (oysters/m(2)), biomass (e dry tissue weight), and shell volume (L/m(2)) data. Age-at-length relationships were estimated from demographic data using a quadratic model. Observed mortality rates were high, and age 3+ oysters were essentially absent. A strong recruitment signal was observed in 1999 and 2002. Between 1998 and 2009, about 30% of the live oysters in the river were harvested as seed, corresponding to similar to 7.5% of the total shell base in an average year. Typically, for every 5 bushels of shell planted, 1 bushel of seed was harvested (20% return). Even with shell planting (similar to 10 L/m(2)/y), the river shell budget showed a deficit with respect to the accretion rate required to balance sea level rise and natural degradation processes. During the study period, the mean river recruit-to-stock ratio was similar to 4. The unusual and consistently high recruit-to-stock ratios suggest that management for modest continuous seed removal may be accomplished without shell planting. Annual stock assessment to identify low recruitment years is recommended as a method to adjust annual seed harvest quotas

Population Studies Of The Native Eastern Oyster, Crassostrea Virginica, (Gmelin, 1791) In The James River, Virginia, Usa

We describe oyster population trends in the James River, VA from 1993 through 2006 using quantitative fishery independent survey data collected using a stratified random design, The 23 reefs contained in the study area cover a total of 2.41 to 4.98 X 10(7) m(2). There is a marked pattern in density of oysters among X 10(7) m(2) and vary in individual size from 1.26 X 10(4) m(2) the reefs: during the Study period a small group of reefs comprising 5.4% of the total a rea consistently contained between 25.7 and 55.5% by number and 35.8 and 54.8% by biomass of the total oyster population. The highest density reefs exhibit, with very few exceptions, mean densities well in excess of 200 oysters m(-2), typically between 300 and 500 m(-2) with a single maximum value of 773 oysters m(-2) in 2002 coincident with the highest annual recruitment observed during the Study period. Recruitment events were usually followed by very high mortality with very small percentages of the population reaching ages \u3e= 3 y of age. A strong stock-recruit relationship is absent; rather population demographics appear to be dominated by periodic high recruitment events. Biomass maxima tended to lag one to two years after recruitment maxima. Standing stock for the total system varied between 1.07 X 10(8) g and 3.31 X 10(8) g (107 and 331 metric tonnes) in 2003 and 2005, respectively as the 2002 recruits grew and suffered mortality. Age-at-length relationships were estimated from demographics: using a July I birth date and a November 1 survey date giving lengths of 37.3 mm at 0.33 y, 58.9 mm at 1.33 y, 80.5 mm at 2.33 y, 102.1 mm at 3.33 y and 123.7 mm at 4.33 y Length demographics were recast as age demographics to estimate annual proportional mortality. Mean proportional mortality values for age 1 oysters range from a low of 0.2-0.4 to a high in excess of 0.7. Age 2 mean proportional mortality values range from a low of 0.41 to a high exceeding 0.75. The proportional mortality for age 3 and 4 y olds generally exceeded mean values of 0.6 with highest values approaching 0.95. In all cases, these values exceeded mortality estimates calculated using traditional box count methods by a considerable margin. The ability to accurately estimate age specific mortality allows the construction of shell (habitat) budgets for the individual reef systems. Shell half-life loss rate estimates in the most productive reefs is between 2 and 3 y and the population is maintained by the continual and extraordinary recruitment in the face of high mortality-the latter driven by disease (predominantly Perkinsus marinus) epizootics. The shell resource, even on the most productive reefs, is modest, equivalent to little more than a monolayer several centimeters thick. Individual reefs demonstrate remarkable stability as either high shell density + high population density associations (high:high) or low shell density + low Population density associations (low:low), even in the face of temporal population and demographic fluctuations associated with disease related mortality. The probability of Manipulating either shell and/or live oyster density to effect the transition of a low:low reef to a high:high reef is considered bleak in the face of extant recruitment and mortality patterns. The primary impediment 10 population expansion or rebuilding is high and uncontrolled mortality rather than a lack of recruitment. Given the large numbers of oysters in low salinity refugia that have the ability to contnually contribute to the larval pool, active selection against disease susceptible oysters on a system wide basis is unlikely

Infectivity of an Infectious Clone of Banana Streak CA Virus in A-Genome Bananas (Musa acuminata ssp.)

We have characterized the complete genome sequence of an Australian isolate of banana streak CA virus (BSCAV). A greater-than-full-length, cloned copy of the virus genome was assembled and agroinoculated into five tissue-cultured plants of nine different Musa acuminata banana accessions. BSCAV was highly infectious in all nine accessions. All five inoculated plants from eight accessions developed symptoms by 28 weeks post-inoculation, while all five plants of M. acuminata AA subsp. zebrina remained symptomless. Symptoms were mild in six accessions but were severe in Khae Phrae (M. acuminata subsp. siamea) and the East African Highland banana accession Igisahira Gisanzwe. This is the first full-length BSCAV genome sequence reported from Australia and the first report of the infectivity of an infectious clone of banana streak virus

Video Conferencing Peer Support and Rarer Forms of Dementia: An Exploration of Family Carers’ Positive Experiences

Little is known regarding the nuanced experiences of family carers for people living with rare dementias (PLWRD), with no known literature exploring their positive experiences of caring discussed within peer support group settings. This article explores family carers of PLWRD’s positive experiences reported in video conferencing peer support groups. Six peer support group sessions involving a total of nine participants were qualitatively analysed using thematic analysis, guided by the conceptual framework of positive aspects of caring (CFPAC) (Carbonneau et al., 2010). Six themes were identified: (1) Protecting, maintaining, enjoying and finding strength in their relationship with the PLWRD; (2) Using tools and resources in response to challenges; (3) Positive impact of interactions and others’ responses to the dementia; (4) Overcoming barriers to taking a break while maintaining their wellbeing, (5) Maintaining positive outlooks and showing psychological resilience in adversity; and (6) Attributing meaning to the caring role. This article highlights family carers of PLWRD’s positive psychological, physical and social resources, balanced against the challenges of caring and maintaining their wellbeing, and identifies ways of promoting family carers’ positive caring experiences and resources within healthcare and supportive settings

Parameters affecting ion intensities in transmission-mode Direct Analysis in Real-Time mass spectrometry

A survey of the effect of temperature, transmission module material and analysis time on ion intensities in transmission mode direct analysis in real time mass spectrometry is presented. Ion intensity profiles obtained for two related compounds are similar when analysed separately but are very different when analysed as a mixture