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Origin and fate of hematopoietic stem precursor cells in the leech Hirudo medicinalis
Full text linkThe hematopoietic process by which blood cells are formed has been intensely studied for over a century using several model systems. An increasing amount of evidence shows that hematopoiesis, angiogenesis, immune response and the regulating these processes (i.e., cytokines) are highly conserved across taxonomic groups. Over the last decade, the leech Hirudo medicinalis, given its simple anatomy and its repertoire of less varied cell types when compared to vertebrates, has been proposed as a powerful model for studying basic steps of hematopoiesis and immune responses. Here, I provide a b
Immune Response: Evolution
No full textInnate immune processes arose from specific host–pathogen coevolutive interactions and the ability to recognise self and nonself structures is extremely conserved from invertebrates to vertebrates.
In this context, phagocytes represent the most ancient defensive line against foreign materials, already present in earliest protostomes.
Moreover, although more complex functions evolved in vertebrates, both cellular and humoral innate immune mechanisms are extremely conserved, leading to identify some forms of innate immune memory also in invertebrates
THE EXTRACELLULAR MATRIX OF THE CUTICLE OF GORDIUS. PRELIMINARY ULTRASTRUCTURAL OBSERVATIONS.
No full textVertebrate rod photoreceptors express both BK and IK calcium-activated potassium channels, but only BK channels are involved in receptor potential regulation
No full textCalcium-activated potassium current in vertebrate rods is sustained by BK and IK channels
No full textVertebrate Rod photoreceptors express both BK and IK calcium-activated potassium channels, but only BK channels are involved in receptor potential regulation
No full textIn salamander rods, Ca(2+)-activated K(+) current (I(KCa)) provides an effective "clamp" of the dark membrane potential to its normal resting level. By a combination of electrophysiological, pharmacological, and immunohistochemical approaches, we show that salamander rods functionally express large-conductance Ca(2+)- and voltage-dependent potassium (BK) channel and intermediate-conductance Ca(2+)-dependent potassium (IK) channel, but not small-conductance Ca(2+)-dependent potassium channel (SK) subtypes. Application of 100 nM iberiotoxin and 100 nM clotrimazole reduced net I(KCa) to 36% and 63%, respectively, whereas the current was unaffected by application of 1 microM apamin. Consistently, anti- SK1, -SK2, and -SK3 antibodies were unable to stain rod photoreceptors, whereas both anti-BK and -SK4/ IK1 antibodies heavily stained the ellipsoid region of the inner segments of the rods. Moreover, by using current-clamp experiments, it was clearly seen that the strong clamping effect of the total I(KCa) was lost when IbTx, but not CLTZ, was applied to the bath. This behavior strongly suggests that of BK and IK channels, only the former are responsible for the clamping effect on the photoreceptor membrane potential
Anellidi
No full textGli Anellidi appartengono al gruppo dei lofotrocozoi, sono celomati primitivi che possiedono uno sviluppato sistema immunitario innato sia tipo cellulare che di tipo umorale. L’immunità cellulare è specifica contro gli agenti patogeni ed è mediata da diversi processi tra i quali la fagocitosi, l'incapsulamento e la citotossicità cellulo mediata contro cellule allogeniche o xenogeniche. Gli Anellidi hanno sviluppato anche un’immunità di tipo umorale che si basa sulle proprietà antimicrobiche, emolitiche e di coaugulazione del loro fluido celomatico. Il presente capitolo è focalizzato sulle diverse strategie di difesa immunitaria delle tre classi degli anellidi: i Policheti, gli Oligocheti e gli Irudine
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