Histone-like protein HU from Deinococcus radiodurans binds preferentially to four-way DNA junctions

The histone-like protein HU from Escherichia coli is involved in DNA compaction and in processes such as DNA repair and recombination. Its participation in these events is reflected in its ability to bend DNA and in its preferred binding to DNA junctions and DNA with single-strand breaks. Deinococcus radiodurans is unique in its ability to reconstitute its genome from double strand breaks incurred after exposure to ionizing radiation. Using electrophoretic mobility shift assays (EMSA), we show that D.radiodurans HU (DrHU) binds preferentially only to DNA junctions, with half-maximal saturation of 18 nM. In distinct contrast to E.coli HU, DrHU does not exhibit a marked preference for DNA with nicks or gaps compared to perfect duplex DNA, nor is it able to mediate circularization of linear duplex DNA. These unexpected properties identify DrHU as the first member of the HU protein family not to serve an architectural role and point to its potential participation in DNA recombination events. Our data also point to a mechanism whereby differential target site selection by HU proteins is achieved and suggest that the substrate specificity of HU proteins should be expected to vary as a consequence of their individual capacity for inducing the required DNA bend.     

Intrastadial developmental resistance of third instar gypsy moths (Lymantria dispar L.) to L. dispar nucleopolyhedrovirus

Gypsy moth larvae become increasingly resistant to lethal infection by the Lymantria dispar M nucleopolyhedrovirus (LdMNPV) as they age within the fourth instar. Newly molted larvae are most sensitive to infection, mid-instars are least sensitive, and late-instars display intermediate sensitivity. This resistance occurs whether the virus is delivered orally or intrahemocoelically. The present study reveals a nearly identical pattern of resistance in third instar larvae. An LD₄₈ dose of polyhedra for newly molted third instars produced 18%, 10%, 8%, 25%, and 24% mortalities in larvae to which virus was orally administered at 12, 24, 48, 72, and 96 hours post-molt (hpm), respectively, which is a 6-fold reduction in mortality between newly molted larvae and mid-instars. An LD₄₄ dose of budded virus for newly molted third instars produced 33%, 23%, 17%, 31%, and 31% mortalities when injected into larvae that were 12, 24, 48, 72, and 96 hpm, respectively, which is a 2.6-fold reduction in mortality between newly molted larvae and mid-instars, indicating that approximately half of this resistance is midgut-based and half is systemically based. Doubling the viral dose did not overcome developmental resistance whether the virus was delivered orally or intrahemocoelically. In addition, time to death was significantly affected by the time post-molt at which the insect was inoculated with the virus. We suggest that intrastadial developmental resistance may affect both the ecology and management of the gypsy moth.     

Exercise training in childhood-onset systemic lupus erythematosus: a controlled randomized trial

Introduction

Exercise training has emerged as a promising therapeutic strategy to counteract physical dysfunction in adult systemic lupus erythematosus. However, no longitudinal studies have evaluated the effects of an exercise training program in childhood-onset systemic lupus erythematosus (C-SLE) patients. The objective was to evaluate the safety and the efficacy of a supervised aerobic training program in improving the cardiorespiratory capacity in C-SLE patients.

Methods

Nineteen physically inactive C-SLE patients were randomly assigned into two groups: trained (TR, n = 10, supervised moderate-intensity aerobic exercise program) and non-trained (NT, n = 9). Gender-, body mass index (BMI)- and age-matched healthy children were recruited as controls (C, n = 10) for baseline (PRE) measurements only. C-SLE patients were assessed at PRE and after 12 weeks of training (POST). Main measurements included exercise tolerance and cardiorespiratory measurements in response to a maximal exercise (that is, peak VO₂, chronotropic reserve (CR), and the heart rate recovery (ΔHRR) (that is, the difference between HR at peak exercise and at both the first (ΔHRR1) and second (ΔHRR2) minutes of recovery after exercise).

Results

The C-SLE NT patients did not present changes in any of the cardiorespiratory parameters at POST (P > 0.05). In contrast, the exercise training program was effective in promoting significant increases in time-to-exhaustion (P = 0.01; ES = 1.07), peak speed (P = 0.01; ES = 1.08), peak VO₂ (P = 0.04; ES = 0.86), CR (P = 0.06; ES = 0.83), and in ΔHRR1 and ΔHRR2 (P = 0.003; ES = 1.29 and P = 0.0008; ES = 1.36, respectively) in the C-SLE TR when compared with the NT group. Moreover, cardiorespiratory parameters were comparable between C-SLE TR patients and C subjects after the exercise training intervention, as evidenced by the ANOVA analysis (P > 0.05, TR vs. C). SLEDAI-2K scores remained stable throughout the study.

Conclusion

A 3-month aerobic exercise training was safe and capable of ameliorating the cardiorespiratory capacity and the autonomic function in C-SLE patients.

Trial registration

NCT01515163.     

Effects of curcumin on methyl methanesulfonate damage to mouse kidney

Methylmethane sulfonate (MMS) is an alkylating agent that may react with DNA and damage it. We investigated histological changes and apoptosis caused by MMS and the effects of curcumin on MMS treated mouse kidneys. Twenty-four mice were divided into four equal groups: controls injected with saline, a group injected with 40 mg/kg MMS, a group injected with 40 mg/kg MMS and given 100 mg/kg curcumin by gavage, and a group given 100 mg/kg curcumin by gavage. MMS caused congestion and vacuole formation, and elevated the apoptotic index significantly, but had no other effect on kidney tissue. Curcumin improved the congestion and vacuole formation caused by MMS and decreased the apoptotic index. Curcumin administered with MMS appears to decrease the deleterious effects of MMS on the kidney.     

Assay of α-difluoromethylornithine in body fluids and tissues by automatic amino-acid analysis

A procedure is described for the measurement of -α-difluoromethylornithine (DFMO), a selective irreversible inhibitor of ornithine decarboxylase, in biological specimens. The drug is separated from other amino acids with a commercial amino-acid analyser and detected by formation of its alkylthio-isoindole derivative with o-phthalaldehyde. DFMO concentrations of 0.1 nmol can be determined in a sample volume of 100 μl. The assay has been used to determine the half-life of DFMO in serum of several species and the relationships between serum and tissue concentrations.