Radial variability of fibrovascular bundle properties of salacca (Salacca zalacca) fronds cultivated on Turi Agrotourism in Yogyakarta, Indonesia

Hakim L, Widyorini R, Nugroho WD, Prayitno TA. 2021. Radial variability of fibrovascular bundle properties of salacca (Salacca zalacca) fronds cultivated on Turi Agrotourism in Yogyakarta, Indonesia. Biodiversitas 22: 3594-3603. Fibrovascular bundles have properties variability not only based on species and varieties but also parts of species. This study, therefore, aims to characterize the FVB fundamental properties (anatomical, chemical, physical and mechanical) of Salacca zalacca (Gaertn.) Voss fronds, based on radial direction. The salacca fronds were divided into three parts, outer, middle as well as inner positions. Then the FVB's anatomical and physical properties were observed by light microscope and gravimetry analysis, respectively. Meanwhile, the variability of chemical and mechanical properties was investigated based on the ASTM standard. According to the results, the outer position has a higher variability of diameter, density, cellulose, lignin, and mechanical properties than the inner position, but has a lower hemicellulose value than the middle and inner position. Furthermore, the relationships between the anatomical, physical, chemical, and mechanical properties were discovered to form a pattern where increasing the mechanical properties is influenced by density and ratio vascular tissue area to total transverse area. Based on the results, the fibrovascular bundle of S. zalacca frond was concluded to possess anatomical, physical, chemical, and mechanical properties variability on the radial direction. There was a correlation between anatomical properties and mechanical properties.

All-organic liquid crystalline radicals with a spin unit in the outer position of a bent-core system

All-organic paramagnetic liquid crystals offer the advantage of a long-range order of liquid crystalline phases and the magnetic properties of the individual molecules.

Structures and apoprotein linkages of phycoerythrobilin and phycocyanobilin

Phycoerythrobilin and phycocyanobilin are covalently attached to the apoproteins of phycoerythrins and phycocyanins. One linkage consists of an ester bond between the hydroxy group of a serine residue and the propionate side chain on one of the inner pyrrole rings (probably ring C). The other linkage is a labile thioether bond between a cysteine residue and the two-carbon side chain on pyrrole ring A. This side chain and both of the α-positions of the ring A are in the reduced state. This constitutes an important structural revision, since, in the structures currently accepted for the phycobilins, the two-carbon side chain on ring A is depicted as an ethylidene grouping and this has been regarded not only as a very characteristic feature of the phycobilins, but also as a probable structural feature of the chromophore of phytochrome, largely on the basis of other analogies with the phycobilins. The ethylidene-containing structures apply instead to artefact forms of the pigments released from the apoproteins by treatment with hot methanol. Cleavage of the ring-A linkage involves an elimination reaction releasing the cysteine residue and generating a double bond in the ring-A side chain. During cleavage in methanol the direction of the elimination is towards the ring, generating the ethylidene double bond. Since this is linked to the conjugated system, the methanol-released pigments differ spectrally from the native phycobilins. During acid-catalysed release of the pigments, the elimination apparently goes in the opposite direction, generating a double bond at the outer position of the side chain. Since this double bond is not linked to the conjugated system, the acid-released pigments remain spectrally identical with their protein-bound counterparts.