Structure and localization of mRNA encoding a pigment dispersing hormone (PDH) in the eyestalk of the crayfish Orconectes limosus

AbstractThe pigment-dispersing hormone (PDH) is produced in the eyestalks of Crustacea where it induces light-adapting movements of pigment in the compound eye and regulates the pigment dispersion in the chromatophores. To study this hormone at the mRNA level, we cloned and sequenced cDNA encoding PDH in the crayfish Orconectes limosus. The structure of the PDH preprohormone consists of a signal peptide, a PDH precursor-related peptide (PPRP) and the highly conserved PDH peptide at the carboxy-terminal end. In situ hybridization in combination with immunocytochemistry revealed four cell clusters expressing PDH in the optic ganglia of the eyestalk. Three clusters stained both with the PDH cRNA probe and the PDH antiserum, however, the perikarya in the lamina ganglionaris (LG) only stained with the PDH antiserum, suggesting the presence of a PDH-like peptide in the LG

Cr5.7Si2.3P8N24 - a Chromium(+IV) Nitridosilicate Phosphate with Amphibole‐type structure

The first nitridic analog of an amphibole mineral, the quaternary nitridosilicate phosphate Cr5.7Si2.3P8N24 was synthesized under high‐pressure high‐temperature conditions at 1400 °C and 12 GPa from the binary nitrides Cr2N, Si3N4 and P3N5, using NH4N3 and NH4F as additional nitrogen source and mineralizing agent, respectively. The crystal structure was elucidated by single‐crystal X‑ray diffraction with microfocused synchrotron radiation (C2/m, a = 9.6002(19), b = 17.107(3), c = 4.8530(10) Å, β = 109.65(3)°). The elemental composition was analyzed by energy dispersive X‐ray spectroscopy. The structure consists of vertex‐sharing PN4‐tetrahedra forming zweier double chains and edge‐sharing (Si,Cr)‐centered octahedra forming separated ribbons. Atomic resolution scanning transmission electron microscopy shows ordered Si and Cr sites next to a disordered Si/Cr site. Optical spectroscopy indicates a band gap of 2.1 eV. Susceptibility measurements show paramagnetic behavior and support the oxidation state Cr+IV, which is confirmed by EPR. The comprehensive analysis expands the field of Cr‐N chemistry and provides access to a nitride analog of one of the most prevalent silicate structures

Photoconvertible fluorescent protein EosFP: biophysical properties and cell biology applications

EosFP is a fluorescent protein from the coral Lobophyllia hemprichii that changes its fluorescence emission from green to red upon irradiation with near-UV light. Here we present the spectroscopic properties of wild-type EosFP and a variety of monomeric and dimeric mutants and provide a structural interpretation of its oligomerization and photoconversion, which is based on X-ray structure analysis of the green and red species that we reported recently. Because functional expression of the monomeric EosFP variant is limited to temperatures of 30°C, we have developed a tandem dimer. This construct, in which two EosFP subunits are connected by a flexible 12 amino acid linker, expresses well after fusion with the androgen and endothelin A receptors at 37°C. A variety of applications in cellular imaging, developmental biology and automated high-content screening applications are presented, which demonstrate that EosFP is a powerful tool for in vivo monitoring of cellular processes.<br/