FLORAL DEVELOPMENT OF HYDROCHARIS MORSUS-RANAE (HYDROCHARITACEAE)

In both male and female flowers of H. morsus-ranae the primordia of the floral appendages appear in an acropetal succession consisting of alternating trimerous whorls. In the male flower a whorl of sepals is followed by a whorl of petals, three whorls of stamens, and a whorl of filamentous staminodes. The mature androecial arrangement therefore consists of two antisepalous stamen whorls, an antipetalous whorl of stamens, and antipetalous staminodes. Shortly before anthesis, basal meristematic upgrowth between filaments of adjacent whorls produces paired stamens, joining Whorls 1 and 3, and Whorl 2 with the staminodial whorl. A central domelike structure develops between the closely appressed filaments of the inner stamen and staminodial whorl, giving the structure a lobed appearance. After petal inception in the female flower a whorl of antisepalous staminodes develop, each of which may bifurcate to form a pair of staminodes. During staminode development a girdling primordium arises by upgrowth at the periphery of the floral apex. The girdling primordium rapidly forms six gynoecial primordia, which then go on to produce six free styles with bifid stigmas. Intercalary meristem activity, below the point of floral appendage attachment, leads to the production of a syncarpous inferior ovary with six parietal placentae. The styles and carpels remain open along their ventral sutures. During the final stages of female floral development, several hundred ovules develop along the carpel walls, and three nectaries develop dorsally and basally on the three antipetalous styles.     

Description and quantification of field attack rates by predatory mites: An example using an electrophoresis method with a species of Antarctic mite

Summary The main features of the size distribution of pelagic and benthic organisms are described, with particular reference to comprehensive studies at a single station, CS2, in the Celtic Sea. These are: 1. A more or less even distribution of biomass in all size classes of pelagic autotrophs. 2. Five size groups of pelagic heterotrophs separated from each other by roughly 10³ differences in individual weight, with three well-defined gaps in the size spectrum between the four smallest size modes. 3. Benthic organisms with three size modes, the microbial peak between the two smallest pelagic modes, the meiofaunal peak between the size of pelagic ciliates and herbivorous macrozooplankton, and the macrobenthic peak at about the same size as the carnivorous macrozooplankton. Differences in the positions of the microbial peaks are thought to be associated with the different nutritional environments of free-living and surface-attached bacteria. Other features of the pelagic heterotroph spectrum are explicable in terms of the known limits to size ratios between prey and predator for suspension feeders. These limits do not apply to the benthos, the size distribution of which is largely determined by physical constraints of the sedimentary environment and the optimisation of size-related life history characteristics. Thus, constraints on body size are entirely different in the two systems, and we see little evidence for coupling between the pelagos and benthos which might result in complementary patterns of size distribution, except perhaps for interactions between the pelagic larvae of macrobenthos and the permanent macrozooplankton at the upper end of the size spectrum.     

Stereoselective aminoacylation of a dinucleoside monophosphate by the imidazolides ofDl-alanine and N-(tert-butoxycarbonyl)-Dl-alanine

Summary The aminoacylation of diinosine monophosphate (IpI) was studied. When the acylating agent was the imidazolide of N-(tert-butoxycarbonyl)-Dl-alanine, a 40% enantiomeric excess of thel isomer was incorporated at the internal 2 site and the positions of equilibrium for the 23 migration reaction differed for theD andl enantiomers. The reactivity of the nucleoside hydroxyl groups decreased in the order 2(3)>internal 2>5, and the extent of reaction was affected by the concentration of the imidazole buffer (pH 7.1). In contrast, reaction of IpI with the imidazolide of unprotectedDl-alanine led to an excess of theD isomer at the internal 2 site, while reaction with the N-carboxy anhydride ofDl-alanine proceeded without detectable stereoselection. The relevance of these results to the evolution of optical activity and the origin of genetically directed protein synthesis is discussed.     

Reactive column HPLC: rapid analysis on RPC-5 of oligoadenylates that differ at the 3'-terminus.

Oligoadenylates can be analyzed according to the type of 3′-terminus (A_nA, A_nAp, and A_nA > p, oligoadenylates that have at the 3′-terminus no phosphate, a 2′(3′)-monophosphate, and a 2′,3′-cyclic phosphate respectively) by hplc on RPC-5 support using a novel dual-column technique. The first column separates A_nAp plus A_nA > p from A_nA, and at the start of the second column a layer of bacterial alkaline phosphatase enzyme converts the A_nAp into A_nA. Hence this A_nA emerges separately from the original A_nA and from the A_nA > p. The technique can be used to analyze a three-component mixture for a single chain length or a mixture of A_nAp and A_nA > p of mixed chain lengths (n = 3 to 7). The presence of poly(U) does not interfere with the analysis.     

Unpacking animal metaphors for commercial relationships in the biotechnology industry

Metaphors are cognitive instruments with the capacity to influence how humans think about the world. Guiding our representations and shaping our experiences, metaphor is of anthropological interest because it is an integral aspect of culture. This paper aims to highlight the role of metaphor in the biotechnology industry. In particular, animal metaphors provide a means of consolidating information. In a culture where time is highly restricted, metaphors enable the speedy transmission of knowledge, placing information in a familiar context or cultural model. Ethnographic findings reveal that animal metaphors contribute to a larger conceptual framework that equates biological evolution with commercial relationships. Depending on the context, metaphors both conceal and reveal different aspects of the financial world, affecting interpretations of the market.     

Urine metabolomics reveals novel physiologic functions of human aldehyde oxidase and provides biomarkers for typing xanthinuria

Classical xanthinuria is a rare inherited metabolic disorder caused by either isolated xanthine dehydrogenase (XDH) deficiency (type I) or combined XDH and aldehyde oxidase (AO) deficiency (type II). XDH and AO are evolutionary related enzymes that share a sulfurated molybdopterin cofactor. While the role of XDH in purine metabolism is well established, the physiologic functions of AO are mostly unknown. XDH and AO are important drug metabolizing enzymes. Urine metabolomic analysis by high pressure liquid chromatography and mass spectrometry of xanthinuric patients was performed to unveil physiologic functions of XDH and AO and provide biomarkers for typing xanthinuria. Novel endogenous products of AO, hydantoin propionic acid, N1-methyl-8-oxoguanine and N-(3-acetamidopropyl) pyrrolidin-2-one formed in the histidine, nucleic acid and spermidine metabolic pathways, respectively, were identified as being lowered in type II xanthinuria. Also lowered were the known AO products, N1-methyl-2-pyridone-5-carboxamide and N1-methyl-4-pyridone-5-carboxamide in the nicotinamide degradation pathway. In contrast to the KEGG annotations, the results suggest minor role of human AO in the conversion of pyridoxal to pyridoxate and gentisaldehyde to gentisate in the vitamin B6 and tyrosine metabolic pathways, respectively. The perturbations in purine degradation due to XDH deficiency radiated further from the previously known metabolites, uric acid, xanthine and hypoxanthine to guanine, methyl guanine, xanthosine and inosine. Possible pathophysiological implications of the observed metabolic perturbations are discussed. The identified biomarkers have the potential to replace the allopurinol-loading test used in the past to type xanthinuria, thus facilitating appropriate pharmacogenetic counseling and gene directed search for causative mutations.