Reaping a good light harvest: Femtosecond spectroscopy uncovered a novel pathway of singlet–singlet excitation‐energy transfer (EET) from bacteriochlorophyll (Bchl) in a purple bacterium to the carotenoid spirilloxanthin (Spx) upon the excitation of Bchl into the Qx band (see picture). This pathway was also clearly identified in steady‐state fluorescence excitation spectra, but only in the presence of Spx. IC=internal conversion.

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The trunk neural crest of vertebrate embryos gives rise to dorsal root ganglion (DRG) sensory neurons and autonomic sympathetic neurons, among other derivatives. We have examined the development of DRG and sympathetic neurons during development in the zebrafish. We found that sensory neurons differentiate rapidly and that their overt neuronal differentiation significantly precedes that of sympathetic neurons in the trunk. Sympathetic neurons in different regions differentiate at different times. The most rostral population, which we call the cervical ganglion, differentiates several days before trunk sympathetic neurons. After undergoing overt neuronal differentiation, sympathetic neurons subsequently express the adrenergic differentiation markers dopamine beta-hydroxylase and tyrosine hydroxylase. A second population of adrenergic nonneuronal cells initially localized with cervical sympathetic neurons appears to represent adrenal chromaffin cells. In more mature fish, these cells were present in clusters within the kidneys. Individual DRG and sympathetic ganglia initially contain few neurons. However, the number of neurons in DRG and sympathetic ganglia increases continuously at least up to 4 weeks of age. Analysis of phosphohistone H3 expression and bromodeoxyuridine incorporation studies suggests that the increases in DRG and sympathetic ganglion neuronal cell number are due wholly or in part to the division of neuronal cells within the ganglia.

Human T-lymphotropic virus type 1 (HTLV-1) is a complex retrovirus encoding regulatory and accessory genes in four open reading frames (ORF I to IV) of the pX region. We have demonstrated an important role of pX ORF I expression, which encodes p12I , in establishment of HTLV-1 infection in a rabbit model and for optimal viral infectivity in quiescent primary lymphocytes. These data indicated that p12 I may enhance lymphocyte activation and thereby promote virus infection. To further define the role of p12 I in cell activation, we characterized the subcellular localization of p12 I in transfected 293T cells and HeLa-Tat cells by multiple methods, including immunofluorescence confocal microscopy, electron microscopy, and subcellular fractionation. Herein, we demonstrate that p12 I accumulates in the endoplasmic reticulum (ER) and cis-Golgi apparatus. The location of p12 I was unchanged following treatments with both cycloheximide (blocking de novo protein synthesis) and brefeldin A (disrupting ER-to-Golgi protein transport), indicating that the protein is retained in the ER and cis-Golgi. Moreover, using coimmunoprecipitation assays, we identify the direct binding of p12 I with both calreticulin and calnexin, resident ER proteins which regulate calcium storage. Our results indicate that p12 I directly binds key regulatory proteins involved in calcium-mediated cell signaling and suggest a role of p12 I in the establishment of HTLV-1 infection by activation of host cells.Human T-lymphotropic virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia and lymphoma and appears to initiate a variety of immune-mediated disorders, including the chronic neural degenerative disease HTLV-1-associated myelopathy/tropical spastic paraparesis (16,44). As a complex retrovirus, HTLV-1 contains the common retroviral genes gag, pol, and env, as well as several regulatory and accessory genes. These regulatory and accessory genes are present in four different open reading frames (ORFs) in the pX region between env and the 3Ј long terminal repeat (LTR) (10,15,39,40). ORFs IV and III encode the regulatory proteins Tax and Rex, respectively, which have been extensively characterized. Tax is a 40-kDa nuclear-localizing protein that increases viral transcription from the HTLV-1 LTR as well as a number of cellular genes involved in host cell proliferation (17,30,34). Rex is a 27-kDa nucleolar-localizing protein that acts at the posttranscriptional level by promoting the cytoplasmic accumulation of unspliced and singly spliced viral RNA (29).Recent studies have provided important new data that indicate a role of the highly conserved ORF I-encoded protein p12 I in HTLV-1 infection. ORF I mRNA has been detected in HTLV-1-infected cells derived from patients with both adult T-cell leukemia and lymphoma and HTLV-1-associated myelopathy/tropical spastic paraparesis and from asymptomatic carriers (3, 5, 9, 10). Moreover, recombinant p12 I is recognized by sera from naturally infected humans and experimentally infected rabbits (14). Pep...