Cyclooxygenase-2 and Prostaglandin E2 Signaling through Prostaglandin Receptor EP-2 Favor the Development of Myocarditis during Acute Trypanosoma cruzi Infection

Inflammation plays an important role in the pathophysiology of Chagas disease, caused by Trypanosoma cruzi. Prostanoids are regulators of homeostasis and inflammation and are produced mainly by myeloid cells, being cyclooxygenases, COX-1 and COX-2, the key enzymes in their biosynthesis from arachidonic acid (AA). Here, we have investigated the expression of enzymes involved in AA metabolism during T. cruzi infection. Our results show an increase in the expression of several of these enzymes in acute T. cruzi infected heart. Interestingly, COX-2 was expressed by CD68⁺ myeloid heart-infiltrating cells. In addition, infiltrating myeloid CD11b⁺Ly6G^- cells purified from infected heart tissue express COX-2 and produce prostaglandin E₂ (PGE₂) ex vivo. T. cruzi infections in COX-2 or PGE₂-dependent prostaglandin receptor EP-2 deficient mice indicate that both, COX-2 and EP-2 signaling contribute significantly to the heart leukocyte infiltration and to the release of chemokines and inflammatory cytokines in the heart of T. cruzi infected mice. In conclusion, COX-2 plays a detrimental role in acute Chagas disease myocarditis and points to COX-2 as a potential target for immune intervention.     

Microspore embryogenesis: establishment of embryo identity and pattern in culture

The developmental plasticity of plants is beautifully illustrated by the competence of the immature male gametophyte to change its developmental fate from pollen to embryo development when exposed to stress treatments in culture. This process, referred to as microspore embryogenesis, is widely exploited in plant breeding, but also provides a unique system to understand totipotency and early cell fate decisions. We summarize the major concepts that have arisen from decades of cell and molecular studies on microspore embryogenesis and put these in the context of recent experiments, as well as results obtained from the study of pollen and zygotic embryo development.     

Fueling Plankton Production by a Meandering Frontal Jet: A Case Study for the Alboran Sea (Western Mediterranean)

A three dimensional biophysical model was employed to illustrate the biological impacts of a meandering frontal jet, in terms of efficiency and persistency of the autotrophic frontal production, in marginal and semi-enclosed seas. We used the Alboran Sea of the Western Mediterranean as a case study. Here, a frontal jet with a width of 15–20 km, characterized by the relatively low density Atlantic water mass, flows eastward within the upper 100 m as a marked meandering current around the western and the eastern anticyclonic gyres prior to its attachment to the North African shelf/slope topography of the Algerian basin. Its inherent nonlinearity leads to the development of a strong ageostrophic cross-frontal circulation that supplies nutrients into the nutrient-starved euphotic layer and stimulates phytoplankton growth along the jet. Biological production is larger in the western part of the basin and decreases eastwards with the gradual weakening of the jet. The higher production at the subsurface levels suggests that the Alboran Sea is likely more productive than predicted by the satellite chlorophyll data. The Mediterranean water mass away from the jet and the interiors of the western and eastern anticyclonic gyres remain unproductive.     

Amiloride-dependent transport is the main mechanism implicated in sodium iinflux regulation in rat mast cells

Mast cell sodium regulation is a largely unknown field. In our effort to study the mechanisms by which mast cells regulate sodium levels, we have examined the effect of amiloride and ouabain on ²²Na entry in rat mast cells in isotonic and hypertonic conditions. Ouabain (0.5 mM) enhances sodium uptake by 32% in isotonic conditions. Hypertonicity increases by 400% the uptake of sodium through an amiloride (1 mM) dependent mechanism. Ouabain has no appreciable effect on the entry of ²²Na in hypertonic conditions. © 1993 Wiley-Liss, Inc.     

Role of Escherichia coli FtsN protein in the assembly and stability of the cell division ring

Deprivation of FtsN, the last protein in the hierarchy of divisome assembly, causes the disassembly of other elements from the division ring, even extending to already assembled proto‐ring proteins. Therefore the stability and function of the divisome to produce rings active in septation is not guaranteed until FtsN is recruited. Disassembly follows an inverse sequential pathway relative to assembly. In the absence of FtsN, the frequencies of FtsN and FtsQ rings are affected similarly. Among the proto‐ring components, ZipA are more sensitive than FtsZ or FtsA rings. In contrast, removal of FtsZ leads to an almost simultaneous disappearance of the other elements from rings. Although restoration of FtsN allows for a quick reincorporation of ZipA into proto‐rings, the de novo joint assembly of the three components when FtsZ levels are restored to FtsZ‐deprived filaments is even faster. This suggests that the recruitment of ZipA into FtsZ‐FtsA incomplete proto‐rings may require first a period for the reversal of these partial assemblies.     

Measurement of nephrolithiasis urinary markers by capillary electrophoresis

A previously developed method for screening organic acidurias by capillary electrophoresis has been validated for oxalate and citrate measurement in urine. Sample pretreatment is minimum, just acidification and centrifugation. Detection is by direct UV. Validation parameters of the method can be considered adequate. Response is linear for both analytes in standards and samples. The assayed ranges were 200–1000 mg/l for citrate and 10–200 mg/l for oxalate. Recoveries ranged from 99.4±3 to 101.7±2.4%, maximum imprecision in oxalate concentration was of 7.6% RSD and limits of detection in samples were 0.67 mg/l for oxalate and 25.9 mg/l for citrate, both lower than the measured values in samples. Identification of increased glyoxylic (oxoacetic acid) and glyceric acids (2,3-dihydroxy propanoic) are also included to facilitate the diagnosis.     

"PCR Karyotype" of Monochromosomal Somatic Cell Hybrids

Following fusion of human diploid fibroblast-derived microcells with mouse A9 cells, we isolated seven monochromosomal hybrids containing a single human chromosome 2, 3, 5, 12, 15, 20, or 22. Cytogenetic analysis as well as PCR karyotyping (chromosome-specific banding pattern generated by Alu-PCR) was performed on all the hybrids. We here present, for the first time, the specific PCR karyotypes of human chromosomes 2 and 20.     

Mychophilus palmatus, a new species (Copepoda: Cyclopoida: Ascidicolidae) associated with the compound ascidian Botryllus leachi Savigny, with remarks on congeneric species and related genera

Presently two species of the genus Mychophilus Hesse, 1865 are known: Mychophilus roseus Hesse, 1865 and Mychophilus fallax Stock, 1967. A hitherto unknown species is described herein as Microphilus palmatus n. sp. The new species is characterized by its urosome much exceeding the cephalosome-metasome in length, the ornamentation of the labrum, the shape of the palp of the first maxilla, the ornamentation of the legs 1–4 and shape of the caudal rami. These and other features of the genus Mychophilus are compared with those from other related genera of the family Ascidicolidae Thorell, 1859.     

Adenosine A1 Receptors in Cultured Cerebellar Granule Cells: Role of Endogenous Adenosine

Abstract: Adenosine A₁ receptors as well as other components of the adenylate cyclase system have been studied in cultured cerebellar granule cells. No significant changes in adenosine A₁ receptor number, assayed by radioligand binding in intact cells, were detected from 2 days in vitro (DIV) until 7 DIV. Nevertheless, a decline in this parameter was detected at 9 DIV. The steady-state levels of α-G_s and α-G_i, detected by immunoblotting, showed similar profiles, increasing from 2 to 5 DIV and decreasing afterward. Forskolin-stimulated adenylate cyclase levels also showed an increase until 5 DIV, decreasing at 7 and 9 DIV. The adenosine A₁ receptor analogue cyclopentyladenosine (CPA) was able to inhibit cyclic AMP accumulation at 2, 5, and 7 DIV but failed to do so at 9 DIV. This inhibition was prevented by the specific adenosine A₁ receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine. The presence of adenosine deaminase in the culture increased adenosine A₁ receptor number during the period studied and induced recovery of the inhibitory effect of CPA, lost after 7 DIV. These data suggest that functional expression of adenosine A₁ receptors and the other components of the adenylate cyclase system is subjected to regulation during the maturation of cultured cerebellar granule cells and demonstrates a key role for endogenous adenosine in the process.