Generalized microsporidiosis caused by Encephalitozoon sp. in a pediatric patient with Bruton's disease

We present the case of a four-year-old boy with a history of repeated upper respiratory tract infections and pyoderma. He presented fever, seizures, inability to talk, loss of swallowing, fine tremor in the upper extremities; positive bilateral Babinski reflex and quadriparesis. The diagnosis of Bruton's disease and generalized microporidiosis was based on immunologic analysis, smear tests with chromotrope R2 stain and indirect immunofluorescense with monoclonal 3B6 antibody for Encephalitozoon species in samples of spinal fluid, bronchial and paranasal sinus aspirates and stool, which were all positive. The patient was treated with albendazol during 72 days; he left the hospital in a good condition, walking, talking and able to swallow. His laboratory test controls were negative; he is followed up in the outpatient department.     

Impaired germinal center reaction in mice with short telomeres

Reduction of germinal center reactivity is a landmark of immunosenescence and contributes to immunological dysfunction in the elderly. Germinal centers (GC) are characterized by extensive clonal expansion and selection of B lymphocytes to generate the pool of memory B cells. Telomere maintenance by telomerase has been proposed to allow the extensive proliferation undergone by B lymphocytes in the GC during the immune response. We show here that late generation mTR(-/-) mice, which lack the mouse telomerase RNA (mTR) and have short telomeres, present a dramatic reduction in GC number following antigen immunization. Upon immunization with an antigen, wild-type splenocyte telomeres are elongated and this is accompanied by a high expression of the telomerase catalytic subunit in the spleen GC. In contrast, telomerase-deficient mTR(-/-) splenocytes show telomere shortening after immunization, presumably due to cell proliferation in the absence of telomerase. All together, these results demonstrate the importance of telomere maintenance for antibody-mediated immune responses and support the notion that telomere elongation detected in wild-type spleens following immunization is mediated by telomerase.     

Terminal regions of mouse nebulin: sequence analysis and complementary localization with N-RAP

The regions of mouse nebulin extending from the ends of the super repeats to the C-terminus and N-terminus were cloned and sequenced. Comparison of the mouse sequence with the previously published human sequence shows that the terminal regions of nebulin are highly conserved. The four phosphorylation motifs and SH3 domain found at the C-terminus of mouse nebulin are identical to those found in human nebulin, with the exception of four conservative substitutions. The modules linking this C-terminal region to the super repeats have deletions relative to both fetal and adult human nebulins that correspond to integral numbers of modules, making the mouse C-terminal simple repeat region among the shortest observed to date. The N-terminal region and the C-terminal modules were expressed in Escherichia coli and used for antibody production. Immunofluorescent labeling of these regions of nebulin in isolated myofibrils demonstrates that they are located near the center of the sarcomere and near the Z-line, respectively. Immunogold labeling with antibodies raised against the N-terminal nebulin sequence localizes this region in the A-band near the tips of the thin filaments. Nebulin localization is complementary to that of N-RAP, another muscle-specific protein containing nebulin-like super repeats; nebulin is exclusively found in the sarcomeres, while N-RAP is confined to the terminal bundles of actin filaments at the myotendinous junction. Cell Motil. Cytoskeleton 3:211-222, 2000 Published 2000 Wiley-Liss, Inc.     

Adult insulin- and glucagon-producing cells differentiate from two independent cell lineages

To analyze cell lineage in the pancreatic islets, we have irreversibly tagged all the progeny of cells through the activity of Cre recombinase. Adult glucagon alpha and insulin beta cells are shown to derive from cells that have never transcribed insulin or glucagon, respectively. Also, the beta-cell progenitors, but not alpha-cell progenitors, transcribe the pancreatic polypeptide (PP) gene. Finally, the homeodomain gene PDX1, which is expressed by adult beta-cells, is also expressed by alpha-cell progenitors. Thus the islet alpha- and beta-cell lineages appear to arise independently during ontogeny, probably from a common precursor.     

Vertebrate predation by sympatric tamarins, Saguinus mystax and Saguinus fuscicollis

Vertebrate predation was examined in sympatric moustached tamarins (Saguinus mystax) and saddle-back tamarins (Saguinus fuscicollis) in the Amazon rainforest of northeastern Peru. Both species prey on frogs and lizards, and very rarely on nestling birds. As a result of divergent foraging strategies, S. mystax primarily exploited frogs at higher strata of the forest, while S. fuscicollis predominantly preyed on reptiles in the lower strata and on the ground. This difference may strengthen the niche differentiation between these two tamarin species that exists with regard to other prey.     

Further studies on the partial double Donnan. Is isosmotic KCl solution isotonic with cells of respiratory trees of the holothurian Isostichopus badionotus Selenka?

As potassium, chloride and water traverse cell membranes, the cells of stenohaline marine invertebrates should swell if exposed to sea water mixed with an isosmotic KCl solution as they do when exposed to sea water diluted with water. To test this hypothesis respiratory tree fragments of the holothurian Isostichopus badionotus were exposed to five isosmotic media prepared by mixing artificial sodium sea water with isosmotic (611 mmol/l) KCl solution to obtain 100, 83, 71, 60 and 50% sea water, with and without 2 mmol/l ouabain. For comparison, respiratory tree fragments were incubated in sea water diluted to the same concentrations with distilled water, with and without ouabain. Cell water contents and potassium and sodium concentrations were unaffected by KCl-dilution or ouabain in isosmotic KCl-sea water mixtures. In tissues exposed to H(2)O-diluted sea water, cell water increased osmometrically and potassium, sodium and chloride concentrations decreased with dilution; ouabain caused a decrease in potasium and an increase in sodium but no effect on chloride concentrations. The isotonicity of the isosmotic KCl solution cannot be adscribed to impermeability of the cell membrane to KCl as both ions easily traverse the cell membrane. Rather, operationally immobilized extracellular sodium ions, which electrostatically hold back anions and consequently water, together with the lack of a cellward electrochemical gradient for potassium, resulting from membrane depolarization caused by high external potassium concentration, would explain the isotonicity of isosmotic KCl solution. The high external potassium concentration also antagonizes the inhibitory effect of ouabain on the Na(+)/K(+) ATPase responsible for sodium and potassium active transport.     

A family of compact plasmid vectors for DNA immunization in humans

DNA immunization technology is based on the availability of adequate vectors for cloning and expression of heterologous immunoactive proteins in mammalian cells. We have developed a family of DNA plasmid vectors suitable to manipulate antigen expression and location. Their in vitro and in vivo functionality and application are also reported. The developed immune response, the aspects considered for vector design, and the possible independent manipulation of both blocks for the generation of bicistronic constructs, make of the pAEC family of plasmid vectors a source for DNA vaccine candidate's development for further evaluation in human clinical trials, and for potential use in the gene therapy approach.     

Lipid composition and vitamin E content in human colostrum and mature milk

Lipidic components, as well as fatty acid composition and vitamin E content were determined in colostrum (days 3-5 of postpartum) and mature milk (day 21) in 8 women from Murcia (Spain). Triglycerides concentration was higher and cholesterol and esterified cholesterol were lower in mature milk than in colostrum, whereas phospholipid content was similar. These differences indicate that the diameter of milk fat globules increases in mature milk. The percentage of medium-chain fatty acids (12:0 and 14:0) increased in mature milk as compared to colostrum, reflecting de novo synthesis of fatty acids. With the only exception of stearic acid which was lower in mature milk than in colostrum, the remaining long-chain fatty acids was similar. The proportion of both linoleic (18:2) and eicosapentaenoic (20:5) acids found in mature milk and colostrum is higher than in studies from other countries and may reflect the intake of high proportions of polyunsaturated fat from vegetable oils and fish in the studied women. Both vitamin E content and vitamin E/linoleic acid ratio in mature milk are lower than in colostrum, evidencing the efficient mechanism of mammary gland vitamin E uptake around parturition.     

Environmental controls over carbon exchange of three forest ecosystems in eastern China

Net ecosystem productivity (NEP) was continuously measured using the eddy covariance (EC) technique from 2003 to 2005 at three forest sites of ChinaFLUX. The forests include Changbaishan temperate mixed forest (CBS), Qianyanzhou subtropical coniferous plantation (QYZ), and Dinghushan subtropical evergreen broad‐leaved forest (DHS). They span wide ranges of temperature and precipitation and are influenced by the eastern Asian monsoon climate to varying extent. In this study, we estimated ecosystem respiration (RE) and gross ecosystem productivity (GEP). Comparison of ecosystem carbon exchange among the three forests shows that RE was mainly determined by temperature, with the forest at CBS exhibiting the highest temperature sensitivity among the three ecosystems. The RE was highly dependent on GEP across the three forests, and the ratio of RE to GEP decreased along the North–South Transect of Eastern China (NSTEC) (i.e. from the CBS to the DHS), with an average of 0.77 ± 0.06. Daily GEP was mainly influenced by temperature at CBS, whereas photosynthetic photon flux density was the dominant factor affecting the daily GEP at both QYZ and DHS. Temperature mainly determined the pattern of the interannual variations of ecosystem carbon exchange at CBS. However, water availability primarily controlled the interannual variations of ecosystem carbon exchange at QYZ. At DHS, NEP attained the highest values at the beginning of the dry seasons (autumn) rather than the rainy seasons (summer), probably because insufficient radiation and frequent fog during the rainy seasons hindered canopy photosynthesis. All the three forest ecosystems acted as a carbon sink from 2003 to 2005. The annual average values of NEP at CBS, QYZ, and DHS were 259 ± 19, 354 ± 34, and 434 ± 66 g C m⁻² yr⁻¹, respectively. The slope of NEP that decreased with increasing latitude along the NSTEC was markedly different from that observed on the forest transect in the European continent. Long‐term flux measurements over more forest ecosystems along the NSTEC will further help verify such a difference between the European forest transect and the NSTEC and provide insights into the responses of ecosystem carbon exchange to climate change in China.     

Life-cycle modification in open oceans accounts for genome variability in a cosmopolitan phytoplankton

Emiliania huxleyi is the most abundant calcifying plankton in modern oceans with substantial intraspecific genome variability and a biphasic life cycle involving sexual alternation between calcified 2N and flagellated 1N cells. We show that high genome content variability in Emiliania relates to erosion of 1N-specific genes and loss of the ability to form flagellated cells. Analysis of 185 E. huxleyi strains isolated from world oceans suggests that loss of flagella occurred independently in lineages inhabiting oligotrophic open oceans over short evolutionary timescales. This environmentally linked physiogenomic change suggests life cycling is not advantageous in very large/diluted populations experiencing low biotic pressure and low ecological variability. Gene loss did not appear to reflect pressure for genome streamlining in oligotrophic oceans as previously observed in picoplankton. Life-cycle modifications might be common in plankton and cause major functional variability to be hidden from traditional taxonomic or molecular markers.