Genetic Dissection of the Signaling Cascade that Controls Activation of the Shigella Type III Secretion System from the Needle Tip.

Many Gram-negative bacterial pathogens use type III secretion systems (T3SSs) for virulence. The Shigella T3SS consists of a hollow needle, made of MxiH and protruding from the bacterial surface, anchored in both bacterial membranes by multimeric protein rings. Atop the needle lies the tip complex (TC), formed by IpaD and IpaB. Upon physical contact with eukaryotic host cells, T3S is initiated leading to formation of a pore in the eukaryotic cell membrane, which is made of IpaB and IpaC. Through the needle and pore channels, further bacterial proteins are translocated inside the host cell to meditate its invasion. IpaD and the needle are implicated in transduction of the host cell-sensing signal to the T3S apparatus. Furthermore, the sensing-competent TC seems formed of 4 IpaDs topped by 1 IpaB. However, nothing further is known about the activation process. To investigate IpaB's role during T3SS activation, we isolated secretion-deregulated IpaB mutants using random mutagenesis and a genetic screen. We found ipaB point mutations in leading to defects in secretion activation, which sometimes diminished pore insertion and host cell invasion. We also demonstrated IpaB communicates intramolecularly and intermolecularly with IpaD and MxiH within the TC because mutations affecting these interactions impair signal transduction.

Hematopoyesis extramedular en paciente con esferocitosis hereditaria asintomática / Extramedullary hematopoiesis in patients with asymptomatic hereditry spherocytosis

En diversas patologías con alteraciones en la producción de los elementos formes de la sangre pueden desarrollarse focos de hematopoyesis extramedular en diferentes sitios. Los más frecuentes son: bazo, hígado, ganglios linfáticos, y más raramente otros órganos como: glándulas adrenales, hillios renales, cartílagos, ligamentos, tejido adiposo, timo, pulmón, mediastino y duramadre de cráneo y columna. Generalmente el proceso es difuso pero pueden formarse grandes tumores de tejido hematopoyético. Las condiciones patológicas de la médula ósea más frecuentemente asociadas a hematopoyesis extramedular son: esferocitosis hereditaria, talasemia, síndromes mieloproliferativos con fibrosis medular, ocupación medular por patologías neoplásicas. presentamos un paciente de 45 años con esferocitosis hereditaria con masas de tejido hematopoyético extramedular paravertebral mediastinal que respondieron favorablemente a la esplenectomía.

Hereditary spherocytosis (HS) is a relatively common inherited hemolytic disorder in northern Europe and in the US. The reported prevalence of HS in Western countries is 1:5000. We describe a patient 45 years old, with hereditary spherocytosis with masses of mediastinal paravertebral extramedullary hematopoietic tissue, with a favorable response to splenectomy. The medical lieterature refers some cases of extramedullary hematopoiesis as a clinical expression of hereditary spherocytosis, mainly as thoracic masses with usually paravertebral localization. HS should be distinguished from other spherocytic hermolytic anemias. Diagnosis is usually made uring infancy or in young adults, but it can be at any moment of their life, until the seventh decade of life. Ocasionally, the diagnosis is first made in old age. The clinical expression of HS is highly variable, ranging from asymptomatic condition to a severe life-threatening hemolytic anemia. Laboratory features include spherocytosis, osmotic fragility, manifestations of hemolytic disease, elevated unconjugated bilirubin and reticulocytosis. The principal diagnostic test, RBC osmotic fragility, measures the surface/volume Ratio of the cells. The treatment of choice of HS in patients with inherited spherocytosis is splenectomy, which corrects hemolytic anemia. According to he literature, cases of failure following splenectomy have been reported.

Hematopoyesis extramedular en paciente con esferocitosis hereditaria asintomática / Extramedullary hematopoiesis in patients with asymptomatic hereditry spherocytosis

En diversas patologías con alteraciones en la producción de los elementos formes de la sangre pueden desarrollarse focos de hematopoyesis extramedular en diferentes sitios. Los más frecuentes son: bazo, hígado, ganglios linfáticos, y más raramente otros órganos como: glándulas adrenales, hillios renales, cartílagos, ligamentos, tejido adiposo, timo, pulmón, mediastino y duramadre de cráneo y columna. Generalmente el proceso es difuso pero pueden formarse grandes tumores de tejido hematopoyético. Las condiciones patológicas de la médula ósea más frecuentemente asociadas a hematopoyesis extramedular son: esferocitosis hereditaria, talasemia, síndromes mieloproliferativos con fibrosis medular, ocupación medular por patologías neoplásicas. presentamos un paciente de 45 años con esferocitosis hereditaria con masas de tejido hematopoyético extramedular paravertebral mediastinal que respondieron favorablemente a la esplenectomía.(AU)

Hereditary spherocytosis (HS) is a relatively common inherited hemolytic disorder in northern Europe and in the US. The reported prevalence of HS in Western countries is 1:5000. We describe a patient 45 years old, with hereditary spherocytosis with masses of mediastinal paravertebral extramedullary hematopoietic tissue, with a favorable response to splenectomy. The medical lieterature refers some cases of extramedullary hematopoiesis as a clinical expression of hereditary spherocytosis, mainly as thoracic masses with usually paravertebral localization. HS should be distinguished from other spherocytic hermolytic anemias. Diagnosis is usually made uring infancy or in young adults, but it can be at any moment of their life, until the seventh decade of life. Ocasionally, the diagnosis is first made in old age. The clinical expression of HS is highly variable, ranging from asymptomatic condition to a severe life-threatening hemolytic anemia. Laboratory features include spherocytosis, osmotic fragility, manifestations of hemolytic disease, elevated unconjugated bilirubin and reticulocytosis. The principal diagnostic test, RBC osmotic fragility, measures the surface/volume Ratio of the cells. The treatment of choice of HS in patients with inherited spherocytosis is splenectomy, which corrects hemolytic anemia. According to he literature, cases of failure following splenectomy have been reported.(AU)

MYD88 L265P is a marker highly characteristic of, but not restricted to, Waldenström's macroglobulinemia.

We evaluated the MYD88 L265P mutation in Waldenström's macroglobulinemia (WM) and B-cell lymphoproliferative disorders by specific polymerase chain reaction (PCR) (sensitivity ∼10(-3)). No mutation was seen in normal donors, while it was present in 101/117 (86%) WM patients, 27/31 (87%) IgM monoclonal gammapathies of uncertain significance (MGUS), 3/14 (21%) splenic marginal zone lymphomas and 9/48 (19%) non-germinal center (GC) diffuse large B-cell lymphomas (DLBCLs). The mutation was absent in all 28 GC-DLBCLs, 13 DLBCLs not subclassified, 35 hairy cell leukemias, 39 chronic lymphocytic leukemias (16 with M-component), 25 IgA or IgG-MGUS, 24 multiple myeloma (3 with an IgM isotype), 6 amyloidosis, 9 lymphoplasmacytic lymphomas and 1 IgM-related neuropathy. Among WM and IgM-MGUS, MYD88 L265P mutation was associated with some differences in clinical and biological characteristics, although usually minor; wild-type MYD88 cases had smaller M-component (1.77 vs 2.72 g/dl, P=0.022), more lymphocytosis (24 vs 5%, P=0.006), higher lactate dehydrogenase level (371 vs 265 UI/L, P=0.002), atypical immunophenotype (CD23-CD27+ +FMC7+ +), less Immunoglobulin Heavy Chain Variable gene (IGHV) somatic hypermutation (57 vs 97%, P=0.012) and less IGHV3-23 gene selection (9 vs 27%, P=0.014). These small differences did not lead to different time to first therapy, response to treatment or progression-free or overall survival.

[Infectious spondylodiskitis and epidural abscess after spinal puncture for pilonidal sinus excision]. / Espondilodiscitis infecciosa y absceso epidural después de una punción subaracnoidea para escisión de sinus pilonidal.

Vertebral infections after spinal puncture are rare and often inadequately documented. Their incidence does not exceed that of spontaneous epidural abscesses and we should therefore be cautious about assuming a causal relation between puncture and an abscess. After analyzing 10 published cases we saw that only half of them reported on aseptic conditions and only 2 patients seem to have had a prior infection. In 3 cases, the abscesses appeared after technically simple punctures whereas half the reports did not even mention the type of puncture. This complication should be considered whenever a patient develops back pain and fever, even if there are no neurological deficits and even after a simple spinal puncture. Given that early diagnosis and treatment have proven effective in improving the survival rate and reducing the rate of neurological sequelae, magnetic resonance images should be ordered urgently so that early treatment can be established.

Espondilodiscitis infecciosa y absceso epidural después de una punción subaracnoidea para escisión de sinus pilonidal / Infectious spondylodiskitis and epidural abscess after spinal puncture for pilonidal sinus excision

Las infecciones vertebrales tras punción subaracnoidea son excepcionales y a menudo están insuficientemente documentadas. Su incidencia no supera la de los abscesos epidurales espontáneos, lo que debería obligarnos a ser prudentes antes de afirmar la relación causal entre punción y absceso. Tras analizar 10 casos publicados observamos que sólo en la mitad de ellos se aportan datos sobre las condiciones de asepsia de las punciones y únicamente en dos pacientes parece haber una infección previa. En tres casos los abscesos aparecen tras punciones técnicamente sencillas, mientras que en la mitad de ellos ni siquiera se menciona este evento. Debe considerarse esta complicación ante un paciente con dolor de espalda y fiebre, aunque no aparezcan déficit neurológicos, e incluso tras punción subaracnoidea sencilla. Es importante solicitar urgentemente una resonancia magnética, con el fin de establecer con premura un tratamiento adecuado, puesto que el diagnóstico y tratamiento precoces han demostrado su eficacia para mejorar la supervivencia y disminuir el porcentaje de pacientes con secuelas neurológicas

Vertebral infections after spinal puncture are rare and often inadequately documented. Their incidence does not exceed that of spontaneous epidural abscesses and we should therefore be cautious about assuming a causal relation between puncture and an abscess. After analyzing 10 published cases we saw that only half of them reported on aseptic conditions and only 2 patients seem to have had a prior infection. In 3 cases, the abscesses appeared after technically simple punctures whereas half the reports did not even mention the type of puncture. This complication should be considered whenever a patient develops back pain and fever, even if there are no neurological deficits and even after a simple spinal puncture. Given that early diagnosis and treatment have proven effective in improving the survival rate and reducing the rate of neurological sequelae, magnetic resonance images should be ordered urgently so that early treatment can be established

Transcriptional activation of a maize calcium-dependent protein kinase gene in response to fungal elicitors and infection.

Plants respond to pathogen infection with the activation of the expression of pathogenesis-related genes, a response that involves Ca2+-regulated protein phosphorylation processes. We report here the isolation of a full-length complementary DNA encoding a calcium-dependent protein kinase (CPK) gene from maize. CPK genes occur in maize as members of a multigene family, but only one specific CPK gene, the ZmCPK10 gene here described, is transcriptionally activated in response to both fungal infection and treatment with fungal elicitors. Activation of the ZmCPK10 gene is extremely rapid. ZmCPK10 transcripts could be detected 5 min after elicitation and reached maximum levels at 30 min after treatment. Afterwards, there was a decline in the level of ZmCPK10 transcripts followed by a basal level of accumulation which is maintained over the time period of elicitor treatment. The activation of this kinase is accompanied by an increase in the level of PRms mRNA, the PRms being a pathogenesis-related protein from maize whose expression is induced in maize tissues in response to fungal infection and treatment with fungal elicitors. In situ mRNA hybridization analysis revealed a remarkable cell-type specific pattern of expression of ZmCPK10 during growth and development of the elicitor-treated or fungus-infected seedling. Moreover, the ZmCPK10 gene is expressed only in those specific cell types in which the PRms gene is also expressed. The involvement of ZmCPK10 in the elicitor-induced signal transduction pathway leading to the activation of PRms gene expression is discussed.

Pigment signatures associated with an anoxic coastal zone: Bahia Concepcion, Gulf of California.

Bahia Concepcion is a coastal lagoon that has bottom anoxic conditions and high pigment concentrations during the summer. The phytoplankton responsible for this pigment increase is enigmatic, therefore we sampled the lagoon to analyze the pigment with a C8-HPLC system to look for signatures of phytoplankton groups. Analysis reveals a low pigment concentration in the mixed layer with a higher concentration of zeaxanthin and increasing values of chlorophyll a, peridinin, and fucoxanthin below, which peaked at the depth where oxygen dramatically decreases and H(2)S increases. Below this depth, a high pigmentation was recorded and the most important signatures were six chlorophyll-like pigments that eluted between the fucoxanthin and the chlorophyll a, and one carotenoid that eluted just after the chlorophyll a. Spectral characteristics of these last pigments are very similar to pigments present in the Chlorobiales group. These results suggest that cyanobacteria, diatoms, and dinoflagellates are responsible for the chlorophyll a increases, though in highly pigmented samples, anoxygenic phototrophic bacteria are probably the main contributors to the increase in pigments.

Cytology of Infection of Maize Seedlings by Fusarium moniliforme and Immunolocalization of the Pathogenesis-Related PRms Protein.

ABSTRACT We have investigated the histology of infection of maize seedlings by Fusarium moniliforme in association with a biochemical host defense response, the accumulation of the PRms (pathogenesis-related maize seed) protein. Light microscopy of trypan blue-stained sections and scanning electron microscopy revealed direct penetration by F. moniliforme hyphae through the epidermal cells of the seedling and colonization of the host tissue by inter- and intracellular modes of growth. Pathogen ingress into the infected tissue was associated with the induction of defense-related ultrastructural modifications, as exemplified by the formation of appositions on the outer host cell wall surface, the occlusion of intercellular spaces, and the formation of papillae. Cellular and subcellular immunolocalization studies revealed that PRms accumulated at very high levels in those cells types that represent the first barrier for fungal penetration such as the aleurone layer of germinating seeds and the scutellar epithelial cells of isolated germinating embryos. A highly localized accumulation of PRms within papillae of the inner scutellar parenchyma cells also occurred, suggesting that signaling mechanisms that lead to the accumulation of PRms in papillae of cell types that are distant from the invading pathogen must operate in the infected maize tissues. Our study also revealed the presence of a large number of fungal cells with an abnormal shape that showed PRms-specific labeling. PRms was found to accumulate in clusters over the fungal cell wall. Taken together, the occurrence of PRms in cell types that first establish contact with the pathogen, as well as in papillae, and in association with fungal cell walls suggests that PRms may have a function in the plant defense response.

Measurement of intracellular pH of maize seeds (Zea mays) during germination by 31P nuclear magnetic resonance spectroscopy.

The 31P NMR spectra of germinating maize seeds showed a single broad resonance that shifted its position as germination proceeded (studied between 0 and 10 days). The resonance was shown to originate from the phosphate groups of phytine (Mg2+, Ca2+ and K+ salt of myoinositol hexakisphosphate) in a subcellular compartment of the embryo scutellar cells. A series of calibration curves for the chemical shift dependence of the phytate resonance in the presence of Mg2+ and Ca2+ were constructed. These calibration curves allowed us to determine that an acidification of the phytate containing compartment in the seed embryo takes place, reaching a minimum at about pH 4 after three days of germination. This acidification could be important in allowing phytate solubilization for export to growing parts of the maize seedling.

The maize pathogenesis-related PRms protein localizes to plasmodesmata in maize radicles.

Pathogenesis-related (PR) proteins are plant proteins induced in response to infection by pathogens. In this study, an antibody raised against the maize PRms protein was used to localize the protein in fungal-infected maize radicles. The PRms protein was found to be localized at the contact areas between parenchyma cells of the differentiating protoxylem elements. By using immunoelectron microscopy, we found that these immunoreactive regions correspond to plasmodesmal regions. This was also true for the parenchyma cells filling the central pith of the vascular cylinder, although PRms mRNA accumulation was not detected in these cells. These findings suggest that for one cell type, the parenchyma cells of the central pith, the protein is imported rather than synthesized. The localization of the PRms protein indicates the possible existence of mechanisms for sorting of plant proteins to plasmodesmata and suggests that this protein may have a specialized function in the plant defense response. These findings are discussed with respect to the structure and function of plasmodesmata in cell-to-cell communication processes in higher plants.