Geminivirus DNA replication and cell cycle interactions

The Geminiviridae family includes a large number of viruses that infect plants and have a unique geminate virion particle, a single-stranded genome of approximately 2.6-3.0 kb, and replicate through a rolling-circle mechanism. Since they encode for just a few proteins (4-6 depending on the members that belong to four different genera), a rich variety of interactions has evolved between viral proteins and host factors to develop the virus replicative cycle. Among them, we have been particularly interested so far: (i). in the interference with cell cycle regulatory proteins of the retinoblastoma-related (RBR)/E2F pathway and (ii). in the interaction with host DNA replication factors necessary for the assembly of a functional replication complex at the viral origin of DNA replication during the rolling-circle stage. Yeast two-hybrid assays revealed that wheat dwarf virus RepA protein, but nor Rep protein, interacts with plant RBR protein. Interestingly, deletion of the C-terminal domain of Rep confers the truncated protein the ability to interact with RBR, suggesting that this domain may hinder the LXCXE RBR-binding motif. Secondary structure predictions support such a possibility.     

Uhl's anomaly in a domestic shorthair cat

A 2-year-old, neutered male, domestic shorthair cat was presented for investigation of dyspnea and episodic weakness. Clinical and ultrasonographic features were consistent with right ventricular cardiomyopathy. Pathological findings documented Uhl's anomaly. Although rare, Uhl's anomaly should be a differential diagnosis for cats with right-sided congestive heart failure. In particular, Uhl's anomaly could be misdiagnosed as arrhythmogenic right ventricular cardiomyopathy due to the similarity of clinical and echocardiographic findings.     

Screening for several potential pathogens in feral pigeons (Columba livia) in Madrid

Background

Pathogens with the zoonotic potential to infect humans, such as Campylobacter jejuni, Campylobacter coli and Chlamydophila psittaci, can be found in feral pigeons (Columba livia). Given the high density of these birds in the public parks and gardens of most cities, they may pose a direct threat to public health.

Methods

A total of 118 pigeons were captured in three samplings carried out in 2006-2007 in public parks and gardens in Madrid, Spain. Standard haematological and morphological analyses were carried out on the pigeons. PCR was used to screen for the presence of Campylobacter jejuni, C. coli and Chlamydophila psittaci. Positive samples were confirmed by DNA sequencing.

Results

The analyses demonstrated a high prevalence of Chlamydophila psittaci (52.6%) and Campylobacter jejuni (69.1%) among the birds captured. In contrast, Campylobacter coli was rarely detected (1.1%).

Conclusions

Pigeons in Madrid can carry Chlamydophila psittaci and Campylobacter jejuni. They may be asymptomatic or subclinical carriers of both pathogens.     

Crystal structures of Fe2+ dioxygenase superoxo, alkylperoxo, and bound product intermediates

We report the structures of three intermediates in the O2 activation and insertion reactions of an extradiol ring-cleaving dioxygenase. A crystal of Fe2+-containing homoprotocatechuate 2,3-dioxygenase was soaked in the slow substrate 4-nitrocatechol in a low O2 atmosphere. The x-ray crystal structure shows that three different intermediates reside in different subunits of a single homotetrameric enzyme molecule. One of these is the key substrate-alkylperoxo-Fe2+ intermediate, which has been predicted, but not structurally characterized, in an oxygenase. The intermediates define the major chemical steps of the dioxygenase mechanism and point to a general mechanistic strategy for the diverse 2-His-1-carboxylate enzyme family.     

Effectiveness of donor natural killer cell alloreactivity in mismatched hematopoietic transplants

T cells that accompany allogeneic hematopoietic grafts for treating leukemia enhance engraftment and mediate the graft-versus-leukemia effect. Unfortunately, alloreactive T cells also cause graft-versus-host disease (GVHD). T cell depletion prevents GVHD but increases the risk of graft rejection and leukemic relapse. In human transplants, we show that donor-versus-recipient natural killer (NK)-cell alloreactivity could eliminate leukemia relapse and graft rejection and protect patients against GVHD. In mice, the pretransplant infusion of alloreactive NK cells obviated the need for high-intensity conditioning and reduced GVHD. NK cell alloreactivity may thus provide a powerful tool for enhancing the efficacy and safety of allogeneic hematopoietic transplantation.     

Validity and reliability of a calcium checklist in early elementary-school children

OBJECTIVE: To create, validate and assess the reliability of a checklist to measure calcium intake in children. DESIGN: Calcium intakes from a checklist and parent-assisted 24-h dietary recall were compared. Checklist reliability was assessed separately. SETTING: After-school programmes in the United States. SUBJECTS: Forty-two children (18 males, 24 females, age = 8.0 +/- 0.9 years) participated in the validation analysis and 49 children (28 males, 21 females, age = 7.5 +/- 0.9 years) in the reliability analysis. RESULTS: No differences in mean calcium intakes were found by method or gender. The checklist correlated well with recall among girls (r = 0.65, P = 0.01) but not boys (r = -0.33, P = 0.19). Agreement over time was above 80% for most foods. CONCLUSION: The calcium checklist is useful for assessing calcium intake among groups of 6-10-year-old children in settings that preclude parental assistance. More research is needed to improve accuracy among boys.