Notes on the ontogeny and structure of the seed-coat of Sclerocarya birrea (Richard) Hochst. subsp. caffra (Sonder) Kokwaro (Anacardiaceae)

The pendulous, bitegmic, anatropous ovulr with dorsal raphe is suspended at the tip of a massive funicle. A group of nurellar cells with intensively staining cell walls, the hypostase sensu stricto , is present. The initially plate-like tanniniferous chalazal-nucellar tissue, with suberin and lignin impregnated cell walls represents a hypostase sensu lato . The mature seed-coat is formed by the raphe, extensive chalaza, adjacent, well-developed, cup-like hypostase sensu lato , remnants of the two integuments and a cuticular layer. The exalbuminous seed of Sclerocarya birrea suhsp. caffra (the Marula), is regarded to he a derived and phylogenetically advanced type. The undifferentiated seed-roat is very similar to that found in Lannea discolor which, like the marula, belongs to the tribe Spondieae. The similarities in the structure of the seed-coat and seed of the marula and L. discolor confirm their proposed close phylogenetir relationship.     

Clarification of the status of Hibiscus (sect. Furcaria) uncinellus (Malvaceae)

Hibiscus uncinellus andH. bifurcatus have been confused in the literature and in the herbarium. The morphological, ecological, and geographic differences between them are presented, and a lectotype is chosen for the former species.Hibiscus uncinellus is virtually confined to Mexico (plus one Guatemalan station), andH. bifurcatus occurs in the West Indies, South America, and Central America, as far north as Honduras.     

Lepidocoleus cf.ulrichi (Machaeridia) from the Trenton Group (Ordovician) of Ontario (Canada)

A specimen of the machaeridianLepidocoleus cf.ulrichi described herein focuses attention on taxonomical difficulties with extremely dorso-ventrally elongated sclerites found in some lepidocoleid taxa.Lepidocoleus ulrichi Withers, 1926 andLepidocoleus sigmoideus Withers, 1926 exhibit very similar appearances and prove indistinguishable based onWithers 1926 criteria. The key to separating taxa as similar as these may instead lie in the most juvenile stages of growth.     

Description of the Male of Laneella perisi (Mariluis) (Diptera: Calliphoridae) n. comb.

The male Laneella perisi (Mariluis) n. comb. is described based on specimens collected in the Cordillera Oriental (1,370–1,450 m asl), Florencia-Suaza, Caquetá, Colombia. A key to separate the two species of the genus Laneella and illustrations of the male genitalia and female abdomen, terminalia, and spermatheca are also presented.     

Molecular dynamics simulation of the DNA triplex d(TC)5.d(GA)5.d(C+T)5.

A molecular dynamics simulation of the DNA triple helix d(TC)5.d(GA)5.d(C+T)5 is described (C+ represents a protonated cytosine residue). The simulation has been performed using the program AMBER 3.1 and includes counterions and explicit solvent under periodic boundary conditions. Both the dynamic and time-averaged behaviour of the system has been analysed. Considerable deviations from the fibre-diffraction model for DNA triple helix structure are observed, including the repuckering of the purine strand sugars that has been identified in some nuclear magnetic resonance (n.m.r.) studies. The simulation suggests that this conformational change may be driven by the possibility of improved interactions between the phosphate groups of this strand and both the solvent and counterions. Several examples of a particular conformational transition are observed, involving correlated changes in the backbone angles alpha and gamma. These transitions provide a possible explanation for some unusual n.m.r. data that have been reported. The structure of the triple helix major groove also suggests an explanation for the observed stabilization of DNA triplexes by polyvalent cations, and their ability to interact with drugs that bind in the minor groove of DNA duplexes.     

Organolanthanoids. XIII. Bis(pentadeuterocyclopentadienyl)ytterbium(II)

The complex (C₅D₅)₂Yb(dme) (dme = 1,2- dimethoxyethane) has been prepared by reaction of Tl(C₅D₅) with ytterbium metal in dme and is isostructural with (C₅H₅)₂Yb(dme). Thermal desolvation under vacuum yields (C₅D₅)₂Yb, for which essentially identical high resolution neutron powder diffraction data were obtained at 294 K and 77 K, but the structure could not be determined.     

New Harpacticoida (Crustacea, Copepoda) from the North Atlantic Ocean. VIII. The description of Eurycletodes (Oligocletodes) quadrispinosa sp.n. and the male of E. (O.) monardi Smirnov (Cletodidae)

Eurycletodes (O.) quadrispinosa Sp.n. and the male of Eurycletodes (O.) monardi are described. E. quadrispinosa differs from the closely related species E. echinatus Lang, E. parasimilis Por and E. arcticus Lang in the setation of segment 1 and 2 Exp P2–P4, of segment 2 Exp p24 and of the Exp P5. Because of the same setation of the A2, Pl-P4 Exp and Exp as the female of E. monardi Smirnov the described male is regarded as that of E. monardi Smirnov. The species were collected at the Iceland Faroe Ridge from depths of 500. 1540 and 2500 m.     

Ichthyosporidium weissii n. sp. (Microsporidia) infecting the arrow goby (Clevelandia ios)

Gonadal infections by a novel microsporidium were discovered in 34% (13/38) of arrow gobies, Clevelandia ios, sampled over a 3‐yr period from Morro Bay Marina in Morro Bay, California. Gonadal tumors had been reported in arrow gobies from this geographic area. The infected gonads, found primarily in females, typically appeared grossly as large, white‐gray firm and lobulated masses. Histological examination revealed large, multilobate xenomas within the ovaries and no evidence of neoplasia. Typical of the genus Ichthyosporidium, the large xenomas were filled with developmental stages and pleomorphic spores. Wet mount preparations showed two general spore types: microspores with mean length of 6.2 (7.0–4.9, SD = 0.6, N = 20) μm and mean width of 4.3 (5.3–2.9, SD = 0.8) μm; and less numerous macrospores with mean length of 8.5 (10.1–7.1, SD = 1.0, N = 10) μm and mean width of 5.5 (6.2–4.8, SD = 0.5) μm. Transmission electron microscopy demonstrated stages consistent with the genus and 35–50 turns of the polar filament. Small subunit rDNA gene sequence analysis revealed that the parasite from arrow gobies was most closely related to, but distinct from Ichthyosporidium sp. based on sequences available in GenBank. We conclude that this microsporidium represents a new species of Ichthyosporidium, the first species of this genus described from a member of the family Gobiidae and from the Pacific Ocean.     

Nonea dumanii sp. nov. (Boraginaceae) from the Taurus mountains (south Turkey)

The new species Nonea dumanii, endemic to the mountains of the western Taurus in south Turkey (C4 Antalya), is described an illustrated based on original collections by the authors. Karyological observations and analysis of ITS1 DNA sequences showed that the species is probably hexaploid with 2n = 6x = 60 and has phylogenetic affinity to the diploid N. monticola from the Paphlagonian mountains as well as to the tetraploid N. anchusoides from northwest Iran and southeast Turkey. From these allopatric species it is morphologically distinct in characters of the indumentum, flower and fruit. Polyploidy is supported as a major driving force for speciation in Nonea, especially in the group of Anatolian mountain species with primary base number x = 10.     

Carotenoids in the muscles of Orconectes limosus (Raf. ) (Crustacea- Decapoda)

Summary The presence of carotenoids pigments in the muscles of Orconectes limosus (Raf.) (Decapoda, Crustacea)- was studied.In extracts separated by means of column and thin-layer chromatography, the following carotenoids were indentified : -carotene, cantaxanthin, lutein, zeaxanthin, neoxanthin, ketocarotenoid and astaxanthin.     

1H NMR study of the binding of Bis(acridines) to d(AT)5.d(AT)5. 1. Mode of binding

1H NMR has been used to investigate the mode of binding to d(AT)5.d(AT)5 of a series of bis(acridine) derivatives connected by different types of linker chains. The length and character (ionic, aliphatic, rigid, and flexible) of the linker chains are found to have a profound effect on the binding of these derivatives to the DNA. Bis(acridine) derivatives with linker chains shorter than 9 A monointercalate under the conditions used in the NMR study, whereas those bis(acridines) with chains of 9.8 A or longer bisintercalate. We find no evidence for the violation of the so-called neighbor exclusion principle. Although all of the bis(acridines) contain the same chromophores, their NMR spectra clearly demonstrate that they form complexes with d(AT)5.d(AT)5 which have different structures. This emphasizes the important effect that the linker chain has on the structure of the intercalation complex.     

1H-n.m.r. study of the folding of ribonuclease 12-(beta-(3-pyridyl)-L-Ala) S-peptide (1-14)

The 1H-n.m.r. spectra (360 MHz) of 12-(beta-(3-pyridyl)-L-Ala) ribonuclease S-peptide (1-14), a tetradecapeptide incorporating (beta-3-pyridyl-L-Ala) instead of His at position 12, have been assigned. The shift vs. temperature dependence has been analyzed at three different pD's in terms of a two-state helix (3-13) in equilibrium coil equilibrium, and the corresponding values for the thermodynamic quantities delta H degrees and delta S degrees determined. Helix populations at 0 degrees C have been measured as a function of pD, showing their dependence on two apparent pKa's at approximately 3.3 and 5.5, with a maximum at pD approximately 4.2. All the obtained results show that the new peptide has very similar folding properties to those shown by S-peptide and particularly to those of C-peptide. The 3-13 helix formed is stabilized by two interactions: a salt-bridge Glu 2-...Arg 10+ and a partial stacking between the aromatic rings of residues Phe 8 and His 12. Calculations involving ring current shifts and potential energies validate the possible existence of this latter interaction, which must present a local geometry defined by chi 81 180 degrees, chi 82 100 degrees, chi 121-60 and chi 122 80.     

1H NMR study of the binding of bis(acridines) to d(AT)5.d(AT)5. 2. Dynamic aspects

Measurements of the 1H NMR spectra and relaxation rates were used to study the dynamic properties of 9-aminoacridine (9AA) and four bis(acridine) complexes with d(AT)5.d(AT)5. The behavior of the 9AA (monointercalator) and that of C8 (bisintercalator containing an eight-carbon atom linker chain) are entirely similar. For both compounds, the lifetime of the drug in a particular binding site is 2-3 ms at approximately 20 degrees C, and neither affects the A.T base pair opening rates. The complex with C10 (bisintercalator containing a 10-carbon atom linker chain) is slightly more stable than the C8 complex since its estimated binding site lifetime is 5-10 ms at 29 degrees C. Base pairs adjacent to the bound C10 are destabilized, relative to free d(AT)5.d(AT)5, but other base pairs in the C10 complex are little affected. Bis(acridine) pyrazole (BAPY) and bis(acridine) spermine (BAS) considerably stabilize those base pairs that are sandwiched between the two acridine chromophores, but in the BAS complex proton exchange from the two flanking base pairs appears to be accelerated, relative to free d(AT)5.d(AT)5. The lifetime of these drugs in specific binding sites is too long (>10 ms) to be manifested in increased line widths, at least up to 41 degrees C. An important conclusion from this study is that certain bisintercalators rapidly migrate along DNA, despite having large binding constants (K>10(6) M-1). For C8 and C10 complexes, migration rates are little different from those deduced for 9AA. The rigid linker chain in BAPY and the charge interactions in BAS retard migration of these two bisintercalators. These results provide new parameters that are useful in understanding the biochemical and biological properties of these and other bisintercalating drugs.     

Energetics of the B-H transition in supercoiled DNA carrying d(CT)x.d(AG)x and d(C)n.d(G)n inserts.

We have studied the B-H transition in the d(AG)x inserts of varying length under superhelical stress. The new data and previously published results for the d(G)31 insert are treated within a phenomenological model of the B-H transition, making it possible to obtain, for the first time, the energy parameters of the B-H transition in the d(AG)x and d(G)n sequences.