Fitness of hatchery-reared salmonids in the wild

Accumulating data indicate that hatchery fish have lower fitness in natural environments than wild fish. This fitness decline can occur very quickly, sometimes following only one or two generations of captive rearing. In this review, we summarize existing data on the fitness of hatchery fish in the wild, and we investigate the conditions under which rapid fitness declines can occur. The summary of studies to date suggests: nonlocal hatchery stocks consistently reproduce very poorly in the wild; hatchery stocks that use wild, local fish for captive propagation generally perform better than nonlocal stocks, but often worse than wild fish. However, the data above are from a limited number of studies and species, and more studies are needed before one can generalize further. We used a simple quantitative genetic model to evaluate whether domestication selection is a sufficient explanation for some observed rapid fitness declines. We show that if selection acts on a single trait, such rapid effects can be explained only when selection is very strong, both in captivity and in the wild, and when the heritability of the trait under selection is high. If selection acts on multiple traits throughout the life cycle, rapid fitness declines are plausible

Managed Metapopulations: Do Salmon Hatchery ‘Sources’ Lead to In-River ‘Sinks’ in Conservation?

Maintaining viable populations of salmon in the wild is a primary goal for many conservation and recovery programs. The frequency and extent of connectivity among natal sources defines the demographic and genetic boundaries of a population. Yet, the role that immigration of hatchery-produced adults may play in altering population dynamics and fitness of natural populations remains largely unquantified. Quantifying, whether natural populations are self-sustaining, functions as sources (population growth rate in the absence of dispersal, λ>1), or as sinks (λ<1) can be obscured by an inability to identify immigrants. In this study we use a new isotopic approach to demonstrate that a natural spawning population of Chinook salmon, (Oncorhynchus tshawytscha) considered relatively healthy, represents a sink population when the contribution of hatchery immigrants is taken into consideration. We retrieved sulfur isotopes (34S/32S, referred to as δ34S) in adult Chinook salmon otoliths (ear bones) that were deposited during their early life history as juveniles to determine whether individuals were produced in hatcheries or naturally in rivers. Our results show that only 10.3% (CI = 5.5 to 18.1%) of adults spawning in the river had otolith δ34S values less than 8.5‰, which is characteristic of naturally produced salmon. When considering the total return to the watershed (total fish in river and hatchery), we estimate that 90.7 to 99.3% (CI) of returning adults were produced in a hatchery (best estimate = 95.9%). When population growth rate of the natural population was modeled to account for the contribution of previously unidentified hatchery immigrants, we found that hatchery-produced fish caused the false appearance of positive population growth. These findings highlight the potential dangers in ignoring source-sink dynamics in recovering natural populations, and question the extent to which declines in natural salmon populations are undetected by monitoring programs

Characterizing the mechanism of cell-cell fusion induced by the bacterium Burkholderia thailandensis

Cell-cell fusion is important for biological processes including fertilization, development, immunity, and microbial pathogenesis. Bacteria in the pseudomallei group of Burkholderia species, including B. thailandensis, spread between host cells by inducing cell-cell fusion. Previous work showed that B. thailandensis -induced cell-cell fusion requires intracellular bacterial motility and a bacterial protein secretion apparatus called the type VI secretion system-5 (T6SS-5), including the T6SS-5 protein VgrG5. However, the cellular level mechanism and T6SS-5 proteins important for bacteria-induced cell-cell fusion remained incompletely described. Using live cell imaging, we found that bacteria used actin-based motility to push on the host cell plasma membrane to form plasma membrane protrusions that extended into neighboring cells. Then, membrane fusion occurred within these membrane protrusions, either proximal to the bacterium at the tip or elsewhere within a protrusion. Expression of VgrG5 by bacteria within membrane protrusions was required to promote cell-cell fusion. Furthermore, a second predicted T6SS-5 protein, TagD5, was also required for cell-cell fusion. In the absence of VgrG5 or TagD5, bacteria in plasma membrane protrusions were engulfed into neighboring cells. Our results suggest that the T6SS-5 effectors VgrG5 and TagD5 are secreted within membrane protrusions and act locally within membrane protrusions to promote membrane fusion. Continued investigation of this pathway will enhance our understanding of the cellular and molecular mechanisms of membrane fusion and cell-cell fusion

THE POROUS MATERIAL SUPPORT USED FOR THE TRANSFER OF A MURAL PAINTING

The subject of considerations by the author, a graduate from the Academy of Fine Arts, Cracow, consists in producing of a new support for the mural painting “Blessing of Tobias” removed from the vaulting of a chapel-mausoleum at Udanin, Sroda District. This painting removed with the use of “distacco” technique had to be placed on a negative mould imitating the shape of vaulting. The original support, as a result of its total decay, has been removed and in its place a mass was placed composed of the ground plaster, casein and polyvinyl acetate, the latter applied as the binder. As the further step was undertaken the preparation of a new support which the operation caused a lot of difficulties in view of the shape of painting (barrel-like bent Rococo cartouche) and its considerable size (2X1.5 m). The possibility was considered to apply the ready semi-products made of porous materials, however, they proved unsuitable to the purpose owing to difficulties with their fitting and fastening to the painting reverse. It has been decided then to apply an expanding and polymerizing resin in the form of hard or half-hard mass that could be placed directly on the painting reverse. A similar experiment has already been carried out at the Istituto Centrale del Restauro, Rome, however, with the use of very expensive and highly sophisticated apparatus and equipment. For preparing the support the foamed polyurethane in the form of resin manufactured by the “BAYER” Company, West Germany has been used. This resin together with cathalyst was mixed in small doses and then cast onto previously strengthened support. This operation required a certain amount of skill and speedy action as the time for mixing was limited to 8 sec. and the expanding reaction and polymerization occur immediately after mixing of components. As the final result a new support was obtained for the transferred painting, possessing nearly ideal properties as it is firm, stable, poorly heat transmitting, insoluble, resistant to weather conditions and biological effects, light in weight, readily transportable, easy in preparing, not expensive, elastic, and — if required — can be removed mechanically

Manipulation of host cell plasma membranes by intracellular bacterial pathogens.

Manipulation of the host cell plasma membrane is critical during infection by intracellular bacterial pathogens, particularly during bacterial entry into and exit from host cells. To manipulate host cells, bacteria deploy secreted proteins that modulate or modify host cell components. Here, we review recent advances that suggest common themes by which bacteria manipulate the host cell plasma membrane. One theme is that bacteria use diverse strategies to target or influence host cell plasma membrane composition and shape. A second theme is that bacteria take advantage of host cell plasma membrane-associated pathways such as signal transduction, endocytosis, and exocytosis. Future investigation into how bacterial and host factors contribute to plasma membrane manipulation by bacterial pathogens will reveal new insights into pathogenesis and fundamental principles of plasma membrane biology