Ontogenetic Variation in the Diurnal Food and Habitat Associations of an Endemic and an Exotic Fish in Floodplain Ponds: Consequences for Niche Partitioning

In floodplain ponds with low piscivore abundance, both endemic Midgley's gudgeons, Hypseleotris sp. 5, and exotic mosquitofish, Gambusia holbrooki, showed significant ontogenetic variation in the use of food and space. Small gudgeons were generally associated with surface and benthic habitats, then restricted their distribution to benthic habitats at a size of approximately 24mm (standard length). The ontogenetic variation in mosquitofish habitat use was less discrete, and could be described as a tendency for larger individuals to be associated with the bottom of the littoral macrophyte beds than with the surface of the macrophyte beds or surface of the limnetic zone. Small gudgeons exhibited high spatial overlap with mosquitofish within the surface habitats of the ponds. All size-class/species comparisons showed significant partitioning of food resources, however, the diets of small gudgeons and mosquitofish were very similar. Therefore, juvenile gudgeons may have to pass through a similar spatial and trophic niche to introduced mosquitofish before recruiting to the adult stage. Possible mechanisms driving the ontogenetic variation in gudgeon and mosquitofish habitat use are discussed. This paper demonstrates that ontogenetic niche shifts at fine spatial scales can affect our interpretation of interactions between native and introduced fishes.     

Differential and common leukemogenic potentials of multiple NUP98-Hox fusion proteins alone or with Meis1

NUP98-Hox fusion genes are newly identified oncogenes isolated in myeloid leukemias. Intriguingly, only Abd-B Hox genes have been reported as fusion partners, indicating that they may have unique overlapping leukemogenic properties. To address this hypothesis, we engineered novel NUP98 fusions with Hox genes not previously identified as fusion partners: the Abd-B-like gene HOXA10 and two Antennepedia-like genes, HOXB3 and HOXB4. Notably, NUP98-HOXA10 and NUP98-HOXB3 but not NUP98-HOXB4 induced leukemia in a murine transplant model, which is consistent with the reported leukemogenic potential ability of HOXA10 and HOXB3 but not HOXB4. Thus, the ability of Hox genes to induce leukemia as NUP98 fusion partners, although apparently redundant for Abd-B-like activity, is not restricted to this group, but rather is determined by the intrinsic leukemogenic potential of the Hox partner. We also show that the potent leukemogenic activity of Abd-B-like Hox genes is correlated with their strong ability to block hematopoietic differentiation. Conversely, coexpression of the Hox cofactor Meis1 alleviated the requirement of a strong intrinsic Hox-transforming potential to induce leukemia. Our results support a model in which many if not all Hox genes can be leukemogenic and point to striking functional overlap not previously appreciated, presumably reflecting common regulated pathways.     

Persistent maternal effects on juvenile survival in North American red squirrels

Maternal effects can have lasting fitness consequences for offspring, but these effects are often difficult to disentangle from associated responses in offspring traits. We studied persistent maternal effects on offspring survival in North American red squirrels (Tamiasciurus hudsonicus) by manipulating maternal nutrition without altering the post-emergent nutritional environment experienced by offspring. This was accomplished by providing supplemental food to reproductive females over winter and during reproduction, but removing the supplemental food from the system prior to juvenile emergence. We then monitored juvenile dispersal, settlement and survival from birth to 1 year of age. Juveniles from supplemented mothers experienced persistent and magnifying survival advantages over juveniles from control mothers long after supplemental food was removed. These maternal effects on survival persisted, despite no observable effect on traits normally associated with high offspring quality, such as body size, dispersal distance or territory quality. However, supplemented mothers did provide their juveniles an early start by breeding an average of 18 days earlier than control mothers, which may explain the persistent survival advantages their juveniles experienced.     

A new brace treatment similar for adolescent scoliosis and kyphosis based on restoration of thoracolumbar lordosis. Radiological and subjective clinical results after at least one year of treatment

Study design

A prospective treatment study with a new brace was conducted Objective. To evaluate radiological and subjective clinical results after one year conservative brace treatment with pressure onto lordosis at the thoracolumbar joint in children with scoliosis and kyphosis.

Summary of background data

Conservative brace treatment of adolescent scoliosis is not proven to be effective in terms of lasting correction. Conservative treatment in kyphotic deformities may lead to satisfactory correction. None of the brace or casting techniques is based on sagittal forces only applied at the thoracolumbar spine (TLI= thoracolumbar lordotic intervention). Previously we showed in patients with scoliosis after forced lordosis at the thoracolumbar spine a radiological instantaneous reduction in both coronal curves of double major scoliosis.

Methods

A consecutive series of 91 children with adolescent scoliosis and kyphosis were treated with a modified symmetric 30 degrees Boston brace to ensure only forced lordosis at the thoracolumbar spine. Scoliosis was defined with a Cobb angle of at least one of the curves [greater than or equal to] 25 degrees and kyphosis with or without a curve <25 degrees in the coronal plane. Standing radiographs were made i) at start, ii) in brace at beginning and iii) after one year treatment without brace.

Results

Before treatment start ??in brace?? radiographs showed a strong reduction of the Cobb angles in different curves in kyphosis and scoliosis groups (sagittal n = 5 all p < 0.001, pelvic obliquity p < 0.001). After one year of brace treatment in scoliosis and kyphosis group the measurements on radiographs made without brace revealed an improvement in 3 Cobb angles each.

Conclusion

Conservative treatment using thoracolumbar lordotic intervention in scoliotic and kyphotic deformities in adolescence demonstrates a marked improvement after one year also in clinical and postural criteria. An effect not obtained with current brace techniques.     

Regulation of cAMP-dependent protein kinase activity by glutathionylation

The catalytic subunit of cAMP-dependent protein kinase (cAPK) is susceptible to inactivation by a number of thiol-modifying reagents. Inactivation occurs through modification of cysteine 199, which is located near the active site. Because cysteine 199 is reactive at physiological pH, and modification of this site inhibits activity, we hypothesized that cAPK is a likely target for regulation by an oxidative mechanism, specifically glutathionylation. In vitro studies demonstrated the susceptibility of kinase activity to the sulfhydryl oxidant diamide, which inhibited by promoting an intramolecular disulfide bond between cysteines 199 and 343. In the presence of a low concentration of diamide and reduced glutathione, the kinase was rapidly and reversibly inhibited by glutathionylation. Mutant kinase containing an alanine to cysteine mutation at position 199 was resistant to inhibition by both diamide and glutathionylation, thus implicating this as the oxidation-sensitive site. Mouse fibroblast cells treated with diamide showed a reversible decrease in cAPK activity. Inhibition was dramatically enhanced when cells were first treated with cAPK activators. Using biotin-cysteine as means for detecting and purifying thiolated cAPK from cells, we were able to show that, under conditions in which cAPK is inactivated by diamide, it is also readily thiolated.