Four proteases (papain, bromelain, R-chymotrypsin and protease SG) were used to catalyze cooligomerizations of L-leucine ethyl ester (L-Et-Leu) with diethyl-L-glutamate (L-(Et) 2 -Glu). Protease added to reaction was normalized based on their relative activities for casein hydrolysis. With the exception of papain that shows a very broad pH optimum for oligo(γ-Et-L-Glu) synthesis, the pH optimum for peptide synthesis was above that for peptide hydrolysis. For L-(Et) 2 -Glu/L-Et-Leu (1:1 mol/mol) co-oligomerizations, the relative order of activities of the four proteases is papain ≈ bromelain > R-chymotrypsin > protease SG. 1 H NMR analyses showed that co-oligopeptide compositions were close in value to the monomer feed ratio. Reactivity ratios, r Leu and r Glu , are nearly identical and have values close to one, suggesting propagation during oligomer synthesis tends to occur randomly giving random sequences along oligopeptides. MALDI-TOF spectra information was obtained on both chain length distribution and chemical composition distribution for oligo(γ-Et-L-Glu-co-∼50mol%-L-Leu) prepared using papain, bromelain, R-chymotrypsin or protease SG as catalysts. From MALDI-TOF generated total abundance intensities, DP avg values of these samples are 7.5, 6.1, 8.5 and 8.7 respectively, which agrees well with values determined by 1 H NMR (7.3, 6.5, 8.2 and 8.5 respectively). Oligo(γ-Et-L-Glu-co-∼50mol%-L-Leu), synthesized using R-chymotrypsin and protease SG, consists of the broadest chain length distributions (5-12 and 6-11, respectively). In contrast, oligopeptides from bromelain and papain catalysis have narrower chain length distributions (5-8 and 6-9, respectively). Also, MALDI-TOF shows a large heterogeneity of leucine contents for oligo(γ-Et-L-Glu-co-∼50mol%-L-Leu) synthesized by all four protease catalysts, consistent with co-oligomerizations occurring by random propagation events. Eight tripeptides representing all possible sequences were prepared by standard solid-state Fmoc-based peptide chemistry. Oligo(γ-Et-L-Glu-co-∼50mol%-L-Leu) chains prepared using all four proteases were degraded to oligomers where the primary constituent in the population was trimers. Using LC-MS to analyze the relative content of tripeptide sequences, and calculating the abundance of triad sequences for a statistically random process, it was found for all four proteases that experimental and theoretical values are in excellent agreement. Hence, in agreement with MALDI-TOF and reactivity ratio results, LC-MS analysis showed that random co-oligopeptides were formed. In other words, for this set of monomers and proteases, no preference or selectivity was observed for addition of L-(Et) 2 -Glu or L-Et-Leu to propagating oligomer chains.

We report for the first time the presence of cluster crystals of calcium oxalate within the glandular trichomes and oil bodies in the mesophyll for Baccharis species. Moreover, the comparative leaf anatomy and micro-morphology of six species of Baccharis, namely B. illinita, B. microdonta, B. pauciflosculosa, B. punctulata, B. reticularioides, and B. sphenophylla is investigated by light and scanning electron microscopy. The studied species exhibited differences in their leaf anatomical features such as the morphology of the cuticle, type and occurrence of the stomata, presence or absence of glandular trichomes, shape of the flagelliform trichomes, and the arrangement of the mesophyll tissues. These differences can be helpful in the species identification and classification and could represent informative characters for the reconstruction of the evolution of the genus.

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Calcium oxalate crystals in higher plants occur in five major forms namely raphides, styloids, prisms, druses and crystal sand. The form, shape and occurrence of calcium oxalate crystals in plants are species- and tissue-specific, hence the presence or absence of a particular type of crystal can be used as a taxonomic character. So far, four different types of needle-like raphide crystals have been reported in plants. The present work describes two new and unusual forms of raphide crystals from the tubers of Dioscorea polystachya—six-sided needles with pointed ends (Type V) and four-sided needles with beveled ends (Type VI). Both of these new types of needles are distinct from the other four types by each having a surrounding membrane that envelopes a bundle of 10–20 closely packed thin crystalline sheets. The previously known four types of needles have solid or homogenous crystalline material, surrounded by a membrane or lamellate sheath called a crystal chamber. Only the Type VI crystals have beveled ends and the needles of the other five types have pointed ends.

Umbellularia californica (California bay laurel) and Laurus nobilis (Mediterranean bay laurel) leaves may be mistaken or used as a substitute on the market due to their morphological similarity. In this study, a comparison of anatomical and chemical features and biological activity of both plants is presented. L. nobilis essential oil biting deterrent and larvicidal activity were negligible. On the other hand, U. californica leaf oil showed biting deterrent activity against Aedes aegypti . The identified active repellents was thymol, along with (-)-umbellulone, 1,8-cineole, and (-)-α-terpineol. U. californica essential oil also demonstrated good larvicidal activity against 1-day-old Ae. aegypti larvae with a LD50 value of 52.6 ppm. Thymol (LD50 = 17.6 ppm), p-cymene, (-)-umbellulone, and methyleugenol were the primary larvicidal in this oil. Umbellulone was found as the principal compound (37%) of U. californica essential oil, but was not present in L. nobilis essential oil. Umbellulone mosquito activity is here reported for the first time.

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