Patterns of MADS-box gene expression mark flower-type development in Gerbera hybrida (Asteraceae)

Background  

The inflorescence of the cut-flower crop Gerbera hybrida (Asteraceae) consists of two principal flower types, ray and disc, which form a tightly packed head, or capitulum. Despite great interest in plant morphological evolution and the tractability of the gerbera system, very little is known regarding genetic mechanisms involved in flower type specification. Here, we provide comparative staging of ray and disc flower development and microarray screening for differentially expressed genes, accomplished via microdissection of hundreds of coordinately developing flower primordia.     

Tracheation of abdominal ganglia and cerci in the house cricket Acheta domesticus (Orthoptera,Gryllidae)

Patterns of tracheation in the abdominal central nervous system and the cerci of Acheta domesticus are described from whole mounts, and light and electron microscopy. The tracheal supply of the ganglia is derived from ventral longitudinal tracheal trunks which have segmental connections to the spiracels. Each abdominal ganglion is served by a single pair of tracheal trunks, except the terminal ganglion, which has two pairs. Within the ganglia, tracheoles occur principally in association with glia-rich areas of the neuropile. We suggest that the respiratory exchange may be concentrated in the cell bodies of neurons and glia. Each cercus has a tracheal supply in paralle with a large air sac which, it is suggested, serves to lighten the cercus, functions as a resonator for sound reception, or facilitates tidal flow of hemolymph and postecdysial expansion of the cercus. No tracheae run continuously between ganglia or between the terminal ganglion and the cerci, and they do not appear to have a potential role as a contact guidance pathway for cercal nerve growth.     

Biosynthesis of retinal in bovine corpus luteum

Bovine corpus luteum tissue was sliced and incubated with beta-[15,15'-(3)H]carotene. The conversion of radioactive beta-carotene into radioactive retinal was substantiated utilizing column chromatography, thin-layer chromatography, high-speed liquid chromatography, and a derivative formation. Lowering of the incubation temperature to 20 degrees C or boiling the tissue eliminated the conversion of beta-carotene to retinal. In addition, other carotenoids and possible oxidation products of beta-carotene in the corpus luteum were investigated. Our results indicate that the bovine corpus luteum possesses the ability to synthesize retinal in situ, which may play a role in reproductive functions.