Effects on kidney disease, fertility and development in mice inheriting a protein-truncating Denys-Drash syndrome allele (Wt1 tmT396)

Denys-Drash syndrome (DDS) is caused by heterozygous mutations of the Wilms’ tumour suppressor gene, WT1, characterised by early-onset diffuse mesangial sclerosis often associated with male pseudohermaphroditism and/or Wilms’ tumourigenesis. Previously, we reported that the Wt1 ^tmT396 allele induces DDS kidney disease in mice. In the present study heterozygotes (Wt1 ^tmT396/+) were generated on inbred (129/Ola), crossbred (B6/129) and MF1 second backcross (MF1-N2) backgrounds. Whereas male heterozygotes on each background were fertile, inbred heterozygous females were infertile. Kidney disease (proteinuria and sclerosis) was not congenital and developed significantly earlier in inbred mice, although with variable onset. Disease onset in MF1-N2 stocks occurred later in Wt1 ^tmT396/+ mice than reported previously for Wt1 ^R394W/+ mice, and while no kidney disease has been reported in B6/129 Wt1 ^+/- mice, B6/129 Wt1 ^tmT396/+ mice were affected. Offspring of both male and female B6/129 and MF1-N2 Wt1 ^tmT396/+ mice developed kidney disease, but its incidence was significantly higher in offspring of female heterozygotes. Wt1 ^{tmT396/tmT396} embryos exhibited identical developmental abnormalities to those reported for Wt1 ^-/- embryos. The results indicate that the Wt1 ^tmT396 allele does not predispose to Wilms’ tumourigenesis or male pseudohermaphroditism, its effect on kidney disease and female fertility depends on genetic background, stochastic factors may affect disease onset, and disease transmission is subject to a partial parent-of-origin effect. Since the Wt1 ^tmT396 allele has no detectable intrinsic functional activity in vivo, and kidney disease progression is affected by the type of Wt1 mutation, the data support the view that DDS nephropathy results from a dominant-negative action rather than WT1 haploinsufficiency or gain-of-function.     

Effect of 6-dimethylaminopurine on electrically activated in vitro matured porcine oocytes

The effect of the protein kinase inhibitor, 6-dimethylaminopurine (6-DMAP), on the maturation promoting factor (MPF) activity, pronuclear formation, and parthenogenetic development of electrically activated in vitro matured (IVM) porcine oocytes was investigated. Oocytes were activated by exposure to two DC pulses, each of 1.5 kV/cm field strength and 60 microsec duration, applied 1 sec apart. In the first experiment, subsequent incubation with 2 or 5 mM 6-DMAP for 3 hr increased the incidence of blastocyst formation compared with no treatment, whereas incubation with 2 or 5 mM 6-DMAP for 5 hr did not. In the proceeding experiments, oocytes exposed to 6-DMAP were incubated with 2 mM of the reagent for 3 hr. Assaying histone H1 kinase activity in the second experiment revealed that the levels of active MPF in electrically activated oocytes treated with 6-DMAP were depleted more rapidly and remained depleted for longer compared with electrical activation alone. The kinetics of MPF activity following 6-DMAP treatment were similar to that found in inseminated oocytes in the third experiment. The effect of 6-DMAP was correlated with an increased incidence of parthenogenetic blastocyst formation. A fourth experiment was undertaken to examine the diploidizing effect of 6-DMAP. Electrically activated oocytes treated with 6-DMAP and cytochalasin B, either alone or in combination, displayed a higher incidence of second polar body retention compared with those that were untreated or treated with cycloheximide alone. After 6 days of culture in vitro, parthenotes exposed to 6-DMAP, either alone or in combination with cytochalasin B, formed blastocysts at a greater rate compared with those exposed to cytochalasin B alone, cycloheximide alone or no treatment. The combined 6-DMAP and cytochalasin B treatment induced the highest rate of blastocyst formation (47%), but the numbers of trophectoderm and total cells in these blastocysts were lower compared with those obtained following exposure to 6-DMAP alone. These results suggest that the increased developmental potential of 6-DMAP-treated parthenotes may be attributable to the MPF-inactivating effect of 6-DMAP, rather than the diploidizing effect of 6-DMAP.     

Heterothermy in an Australian passerine, the Dusky Woodswallow (Artamus cyanopterus)

Information regarding passerine heterothermy and torpor is scant, although many species are small and must cope with a fluctuating food supply and presumably would benefit from energy savings afforded by torpor. We studied whether insectivorous Dusky Woodswallows (Artamus cyanopterus; ∼35 g) enter spontaneous torpor (food ad libitum) when held outdoors as a pair in autumn/winter. Woodswallows displayed pronounced and regular daily fluctuations in body temperature (T _b) over the entire study period. The mean T _b ranged from ∼39°C to 40°C (photophase, day time) and ∼33°C to 36°C (scotophase, night time). However, on 88% of bird nights, nocturnal T _b minima fell to < 35°C. The lowest T _b observed in air was 29.2°C. However, when a bird fell into water its T _b dropped further to ∼22°C; this T _b was regulated for several hours and the bird survived. Our observations suggest that heterothermy is a normal part of the daily thermal regime for woodswallows to minimise energy expenditure. Spontaneous nocturnal torpor in captive woodswallows suggests that torpor in the wild may be more pronounced than recorded here because free-living birds are likely challenged by both low food availability and adverse weather.     

A Neuronal Relay Mediates a Nutrient Responsive Gut/Fat Body Axis Regulating Energy Homeostasis in Adult Drosophila

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Creatine kinase isoenzyme activity during and after an ultra-distance (200 km) run

It is commonly assumed that creatine kinase (CK) activity in plasma is related to the state of an inflammatory response at 24-48 h, and also it has shown biphasic patterns after a marathon run. No information is available on CK isoenzymes after an ultra-marathon run. The purpose of the present study is to examine the CK isoenzymes after a 200 km ultra-marathon run and during the subsequent recovery. Blood samples were obtained during registration 1 2 h before the 200-km race and during the race at 100 km, 150 km and at the end of 200 km, as well as after a 24 h period of recovery. Thirty-two male ultra-distance runners participated in the study. Serum CPK showed a marked increase throughout the race and 24 h recovery period (p < 0.001). Serum CK during the race occurs mostly in the CK-MM isoform and only minutely in the CK-MB isoform and is unchanged in the CK-BB isoform. High-sensitivity C-reactive protein (hs-CRP), oestradiol, AST and ALT increased significantly from the pre-race value at 100 km and a further increase took place by the end of the 200 km run. The results of our study demonstrate a different release pattern of creatine kinase after an ultra-distance (200 km) run compared to the studies of marathon running and intense eccentric exercise, and changes in several biomarkers, indicative of muscle damage during the race, were much more pronounced during the latter half (100–200 km) of the race. However, the increases in plasma concentration of muscle enzymes may reflect not only structural damage, but also their rate of clearance.     

Motif kernel generated by genetic programming improves remote homology and fold detection

Background  

Protein remote homology detection is a central problem in computational biology. Most recent methods train support vector machines to discriminate between related and unrelated sequences and these studies have introduced several types of kernels. One successful approach is to base a kernel on shared occurrences of discrete sequence motifs. Still, many protein sequences fail to be classified correctly for a lack of a suitable set of motifs for these sequences.     

The changing faces of Streptococcus antigen I/II polypeptide family adhesins

Streptococcus mutans antigen I/II (AgI/II) protein was one of the first cell wall‐anchored adhesins identified in Gram‐positive bacteria. It mediates attachment of S. mutans to tooth surfaces and has been a focus for immunization studies against dental caries. The AgI/II family polypeptides recognize salivary glycoproteins, and are also involved in biofilm formation, platelet aggregation, tissue invasion and immune modulation. The genes encoding AgI/II family polypeptides are found among Streptococcus species indigenous to the human mouth, as well as in Streptococcus pyogenes, S. agalactiae and S. suis. Evidence of functionalities for different regions of the AgI/II proteins has emerged. A sequence motif within the C‐terminal portion of Streptococcus gordonii SspB (AgI/II) is bound by Porphyromonas gingivalis, thus promoting oral colonization by this anaerobic pathogen. The significance of other epitopes is now clearer following resolution of regional crystal structures. A new picture emerges of the central V (variable) region, predicted to contain a carbohydrate‐binding trench, being projected from the cell surface by a stalk formed by an unusual association between an N‐terminal α‐helix and a C‐terminal polyproline helix. This presentation mode might be important in determining functional conformations of other Gram‐positive surface proteins that have adhesin domains flanked by α‐helical and proline‐rich regions.     

Rituximab treatment in rheumatoid arthritis: how does it work?

Treatment with the chimerical monoclonal antibody rituximab results in CD20-directed B cell depletion. Although this depletion is almost complete in the peripheral blood of nearly all patients with rheumatoid arthritis, a proportion of patients does not exhibit a clinical response. The paper by Nakou and colleagues suggests that a decrease in CD19+CD27+ memory B cells in both peripheral blood and bone marrow precedes the clinical response to rituximab. This finding adds to the emerging evidence that lack of response to rituximab is associated with persistence of B lineage cells in specific body compartments.