Asymmetric reduction of ketones by biocatalysis using medlar (Mespilus germanica L) fruit grown in Algeria

Abstract

The biocatalytic reduction of ketones was performed using medlar fruit (Mespilus germanica L), which is grown in large amounts in Algeria. Experiments were performed using aqueous medium with fresh medlar. Prochiral heteroaryl ketones containing furan, thiophene, chroman, and thiochroman moieties were reduced with enantiomeric excess (ee) of up to 98%. High enantioselectivities have been observed especially for the bioreduction of tetralone 4 and thiochromanone 5 with ee of 89% and 98%, respectively. Bioreduction using different parts of medlar indicate that chromanone 6 was reduced with good asymmetric inductions 77% < ee < 85% whichever part of fruit was employed (whole, flesh, or juice) and medlar juice exhibited the best activity.     

The Multiple Epidermis-Cuticle Complex of Medlar Fruit Mespilus germanica L. (Rosaceae)

In order to determine the authenticity of the multiple epidermallayers in the pomaceous fruit of Medlar or Mespil (Mespilusgermanica L.), developmental studies were made from 2 weeksbefore anthesis through harvest and storage. Various histochemicaltechniques were used for the determination of epidermal cellwall structures and cell contents, and for the isolation andstudy of the cuticular membranes. The multiseriate epidermisis derived from successive tangential divisions of the initiallyuniseriate epidermis commencing about 3 weeks post-anthesis.The divisions occur simultaneously around the fruit circumferenceand result in the formation of a normally four- to five-layeredepidermis at fruit maturity. As each epidermal layer is derivedit concomitantly develops a distinct, flanged cuticle that remainspersistent until sloughing of the layer occurs. Evidence providedby light and scanning electron microscopy indicates the presenceof discrete ubiquitous pores and non-anastomosing, anticlinallyoriented canals in the cuticular membranes. Measurements weremade of individual cuticular membrane thicknesses during development,and of cuticular pore dimensions in the mature fruit; cuticularpore numbers were calculated. A brief study was made of therelationship between lenticel development and development ofthe multiseriate epidermis. Mespilus germanica L., Medlar (Mespil) fruit, multiseriate epidermis, cuticular membrane, cuticular pores, transcuticular canals, lenticels     

Punica granatum L. (pomegranates) from early Roman contexts in Vindonissa (Switzerland)

At the later legionary camp of Vindonissa, early Roman (Augustan-Claudian) structures were excavated during a rescue excavation between 1996 and 1998. In phase 2 (10 B.C. until 0), seven in situ carbonised wooden barrels, dug into the ground, were found. They belonged to a rather large building which was most probably used as storage facility. Two of the barrels contained, in the bottom layers, several hundred seeds and pericarp fragments of Punica granatum L. (pomegranates). A large number of other "exotic" plant taxa such as olive, walnut, pine, pistacio, peach, cherry (and probably date) were also found in rather large quantities. Above all, the finds of pomegranates are unique: they are the first finds of this Mediterranean fruit in regions north of the Alps. The origin, use, and other archaeological finds of the pomegranate in the Roman period are discussed. A comparison with other early Roman spectra shows that such large quantities of "exotic" useful plants are mainly present at larger military sites like the legionary camps of Novaesium or Oberaden. It must also be suggested that the pre-camp phases in Vindonissa already had a military charaeter, although this is not at all clear from the other archaeological finds. The precise role of the site is still a matter of debate. Received November 22, 2001 / Accepted February 19, 2002     

Spatial Orientation in Blattella germanica L. Larvae

The aim of these experiments was to investigate the type of cues used in homing processes by young Blattella germanica L. larvae. Several types of stimuli were tested: path integration with kinesthetic cues and visual orientation with landmark cues. Tests measured the escape direction of larvae from the food box after disturbance. Either type of cue alone, path integration or visual landmarks, was sufficient to allow larvae to orient towards their shelters, but they oriented more precisély when both types of cue were used. When several landmark cues (proximal and distal) were present, their relative angular position seemed important in the orientation process. Macroscopic shapes in the environment appeared to be used as a global image, memorized to reach the shelter.     

Molluscicidal activity and new flavonoids from Egyptian Iris germanica L. (var. alba)

The molluscicidal activity of leaf and rhizome extracts of Iris germanica L. (var. alba) against Biomphalaria alexandrina snails was evaluated and the rhizome extracts were found to be the most potent. Activity-guided fractionation revealed that the chloroform extract showed the highest molluscicidal activity (LC90 = 1.26 mg/l) among the tested extracts of the rhizomes. Fraction B prepared from the chloroform extract was the most potent molluscicide (LC90 = 0.96 mg/l) in addition, it showed a significant heart rate reduction in the snail after a 6- to 24-h exposure period. It also displayed a significant level of cercaricidal potential in a time-concentration relationship pattern. Chromatographic fractionation and purification of fraction B resulted in the isolation of two novel compounds: 5,2'-dihydroxy-3-methoxy-6,7-methylenedioxyflavone and 5,7,2'-trihydroxy-6-methoxyflavanone. Their structures were established by one- and two-dimensional NMR methods and mass spectrometry.     

Aspergillosis in German cockroach Blattella germanica (L.) (Blattoidea: Blattellidae)

Natural infection of Aspergillus flavus was observed in adults of Blattella germanica. Though the adult insects exhibited no external symptoms, they became hypoactive and later died. The dead and experimentally infected insects repeatedly yielded Aspergillus flavus in culture on Czapek's medium. Direct microscopic observation of the tissues of infected insects revealed fungal material. The blood films stained with Giemsa stain showed granulocytes (GRs) engulfing fungal hyphae. A remarkable increase in GR and plasmatocyte (PL) counts occurred in differential haemocyte counts (DHCs) of the infected insects. Two main types of immunological responses of the insect noticed were phagocytosis and encapsulation. DHC showed maximum involvement of GRs and PLs in immune mechanism. This revised version was published online in June 2006 with corrections to the Cover Date.     

Nuclear rDNA variability in laboratory strains of the German cockroach Blattella germanica L. (Blattellidae)

The polymorphism of nuclear ribosomal DNA has been studied in male German cockroaches. The RFLP analysis has been used to identify seven types of HindIII fragments, the variation of which may serve as the basis for the differentiation of laboratory strains with respect to some population indices, including the average number of fragments per animal (N), the proportion of polymorphic loci (P), and the average pairwise similarity (APS). The interpopulation variation (FST) calculated for nine haplotypes is 53.85%.     

Ultrastructure de l'iléon de Blatella germanica L. (Dictyoptère)

Résumé L'iléon de Blatella germanica est un important segment d'accumulation minérale. Les nombreuses concrétions d'origine ergastoplasmique, contiennent du phosphore, du chlore, du calcium, du magnesium, du potassium et du fer dans un stroma glycoprotéique. La paroi de ce segment protodéal est constituée d'un type cellulaire unique caractérisé par la présence de feuillets apicaux et d'invaginations basales, différenciations membranaires décrites dans d'autres organes de transit, mais dont la coexistence constitue l'originalité de l'iléon. La signification physiologique de ce segment digestif est discutée.

---

Ultrastructure of the ileum in Blatella germanica L. (Dictyoptera)Localisation, origin and composition of intracellular mineralized concretions

Summary The ileum of Blatella germanica is an important proctodeal segment of mineral accumulation. The numerous concretions, elaborated by the ergastoplasm, contain P, Cl, Ca, Mg, K and Fe in a glycoproteic matrix. The epithelium of this segment is composed by only one type of cells which are characterized by apical leaflets and basal infoldings. These membraneous differenciations have been already described in other transit organs, but their coexistence is typical of the ileum. The physiological significance of this digestive segment is discussed.

Avec la collaboration technique de Melle M. Oricco. Recherches effectuées dans le cadre de la RCP no 162 du C.N.R.S.     

The behaviour of wasps (Vespula germanica L. andV. Vulgaris L.) when foraging

Summary While foraging on dead adult and pupal honeybees, individual wasps showed little conformity in the order in which they dismembered their prey; they attempted to take as large loads as possible and preferred abdomens and thoraces to heads.Although wasps always removed some of the appendages from thoraces, especially the hind and middle legs, the presence of these appendages did not encourage foraging or facilitate recognition of the prey.Pupae were preferred to newly emerged bees, and newly emerged bees to old bees, probably because of the difference in hardness of the cuticle. Whereas wasps learnt to divide adult bodies at the neck and waist, they showed considerable adaptability when dismembering pupae and when confronted with unusual situations. Although individuals tended to become conditioned to collecting one type of prey, some changed from collecting adults to collecting pupae.Wasps could easily be enticed away from meat by offering sugar syrup, but the change from syrup to meat was much more difficult, although it happened occasionally.Some wasps attempted to defend a supply of food against other would-be collectors. Despite their wariness of each other, wasps were attracted to the sight of others at a food source. The frequency with which a wasp continues to visit a site that has ceased to yield food depends on its previous foraging experience there.     

Intergeneric hybrids between Crataegus L. and Mespilus L.: a fresh look at an old problem

A brief outline is given of the history and nomenclature of the sexual and graft hybrids (chimeras) between Crataegus and Mespilus. An investigation has been made of some aspects of the macromorphology, the pollen fertility and exine characters, cytology and physiology of the plants growing in the Royal Botanic Gardens, Kew. It is suggested that in the past too much emphasis has been laid on the anatomy of the epidermal layers and the separation of parental characters in chimeras. Observations made during the study show the presence of intermediate characters in the graft hybrid as well as in the sexual hybrid and there is evidence that most parts of the graft hybrids are probably influenced by both the parental genotypes.     

First evidence of autotriploidization in sterlet (Acipenser ruthenus)

Polyploidization has played an important role in vertebrate evolution. Acipenseridae bring clear examples of polyploidy ancestry and, also, polyploidization seems to be an ongoing process in these fishes. In the present study, the genetic origin of six triploid specimens morphologically determined as Acipenser ruthenus from commercial aquaculture was analyzed using a combination of mitochondrial and nuclear markers. A further five successive statistical analyses including median joining of mitochondrial DNA control region sequences, principal coordinate analysis (PCA), factorial correspondence analysis (FCA), STRUCTURE assignation, and NewHybrids status determination for microsatellite data were applied for the clarification of the origin of one extra chromosome set added in these triploids genomes. Although interspecific hybridization had been suggested as a source of these triploids, the statistical analyses showed that the investigated triploids originate from autotriploidization rather than from interspecific hybridization. Therefore, we conclude that a combination of molecular markers with suitable statistical analyses should be used to verify the origin of unusual ploidy level. Evidently, such an approach is critically essential in aquaculture, where interspecific hybridization is very common and usually detected by changes in ploidy levels only.     

A microdialysis study of allatostatin degradation in Blattella germanica (L.) (Dictyoptera, Blattellidae)

Allatostatins with a typical C‐terminal sequence YXFGL‐NH₂ are insect neuropeptides with inhibitory properties upon Juvenile Hormone production in the corpora allata, vitellogenin release by the fat body, and gut and dorsal vessel motility. All these biological effects are rapidly reversible, suggesting the occurrence of effective mechanisms for inactivation of the peptides. We have studied the degradation of DRLYSFGL‐NH₂ (BLAST‐2), one of the allatostatins of Blattella germanica, in the internal milieu of adult females of this cockroach. The experimental approach combined the use of the radioiodinated derivative [¹²⁵I‐Tyr⁴]BLAST‐2, microdialysis techniques and HPLC analysis with a radioisotope detector. Under these experimental conditions, the half‐life of BLAST‐2 in the internal milieu of the adult female of B. germanica was between 3 and 6 min. Such a short half‐life explains the high doses of allatostatins required to obtain the expected biological effects when tested in vivo, and suggests that circulating allatostatins are subject to rapid rates of synthesis and degradation in order to be operative physiologically.     

Biochemistry and regulation of pheromone production in Blattella germanica (L.) (Dictyoptera,Blattellidae)

Females of the German cockroach, Blattella germanica, produce a contact sex pheromone consisting of the methyl ketones 3,11-dimethyl-2-heptacosanone, 3,11-dimethyl-2-nonacosanone, 29-hydroxy- and 29-oxo-3,11-dimethyl-2-nonacosanone. We review evidence in support of the hypothesis that in adult females the hydrocarbon 3,11-dimethylnonacosane is oxidized to the corresponding methyl ketone pheromone. Recent studies on the precursors and directionality of synthesis of the methyl-branched alkane indicate that it is formed by the insertion of methylmalonyl units derived from propionate, isoleucine, valine, methionine and succinate early in chain elongation. The hydrocarbon is then hydroxylated and oxidized at the 2-position to form the methyl ketone pheromone. The in vivo synthesis of pheromone and its accumulation on the cuticle are correlated to the synthesis of juvenile hormone (JH) by the corpora allata (CA) in vitro and to oocyte development, suggesting common regulation by JH of pheromone production as well as other reproductive events. The patterns of pheromone and hydrocarbon production in starved, allatectomized and head-ligated females, as well as in females rescued with hormone-replacement therapy, suggest two mechanisms of regulation of pheromone production: a JH-induced conversion of hydrocarbon to pheromone is related to the CA cycle and to oocyte development, while a JH-independent mechanism, which is probably related to feeding, supplies precursors for hydrocarbon biosynthesis.     

First evidence of miniature transposable elements in sponges (Porifera)

Transposable elements play a vital role in genome evolution and may have been important for the formation of the early metazoan genome, but only little is known about transposons at this interface between unicellular opisthokonts and Metazoa. Here, we describe the first miniature transposable elements (MITEs, Queen1 and Queen2) in sponges. Queen1 and Queen2 are probably derived from Tc1/mariner-like MITE families and are represented in more than 3,800 and 1,700 copies, respectively, in the Amphimedon queenslandica genome. Queen elements are located in intergenic regions as well as in introns, providing the potential to induce new splicing sites and termination signals in the genes. Further possible impacts of MITEs on the evolution of the metazoan genome are discussed.