Somatic antigens of Pseudomonas aeruginosa. The structure of O-specific polysaccharide chains of the lipopolysaccharides from P. aeruginosa O1 (Lányi), O3 (Habs), O13 and O14 (Wokatsch), and the serologically related strain NCTC 8505

Lipopolysaccharides from Pseudomonas aeruginosa O1 (Lányi classification), O3 (Habs classification), O13 and O14 (Wokatsch classification), and strain NCTC 8505, which is also related to serogroup O3 (Habs), have structurally similar O-specific polysaccharide chains built up of tetrasaccharide repeating units involving L-rhamnose (Rha), 2-acetamido-2-deoxy-D-glucose (GlcNAc), 2-acetamido-2-deoxy-L-galacturonic acid (GalNAcA), and a di-N-acyl derivative of bacillosamine (BacN): 2,4-diacetamido-2,4,6-trideoxy-D-glucose or 2-acetamido-2,4,6-trideoxy-4-[(S)-3-hydroxybutyramido]-D-glucose. The latter derivative was obtained free by solvolysis with hydrogen fluoride of carboxyl-reduced Habs O3 polysaccharide, and was identified by 1H-nuclear magnetic resonance spectroscopy and by mass spectrometry of the corresponding methylated alditol. Habs O3, Lányi O1, and Wokatsch O14 polysaccharides contained O-acetyl groups. Solvolysis with hydrogen fluoride of the native Habs O3 polysaccharide resulted in selective cleavage of the glycosidic linkages of 6-deoxy sugars to give the trisaccharide fragment involving all three N-acylated amino sugars. Similar solvolysis of NCTC 8505 polysaccharide afforded a mixture of disaccharide and trisaccharide with N,N'-diacetylbacillosamine at the reducing end. Smith degradation of Habs O3 polysaccharide resulted in selective oxidation of rhamnose to give a glycoside of a trisaccharide with glyceraldehyde as the aglycone. Smith degradation of NCTC 8505 polysaccharide was complicated by the formation of the glycoside of a trisaccharide with an aglycone of unknown structure. A trisaccharide with rhamnose at the reducing end was also isolated after Smith degradation of the latter polysaccharide. Analysis of the composition and structure of all oligosaccharides obtained, and detailed examination of the 13C-nuclear magnetic resonance spectra of these oligosaccharides, and of both intact and modified polysaccharides, revealed the following structures of the repeating units. The structure for the NCTC 8505 polysaccharide differs from that proposed previously [Tahara, Y. and Wilkinson, S.G. (1983) Eur. J. Biochem. 134, 299-304] in the configurations assigned to the glycosidic linkages of rhamnose and bacillosamine. The results obtained show the P. aeruginosa strains studied to represent three different O-serotypes in a single O-serogroup (Formula: see text).     

IR and Raman study on the interactions of the 5′-GMP and 5′-CMP phosphate groups with Mg(II), Ca(II), Sr(II), Ba(II), Cr(III), Co(II), Cu(II), Zn(II), Cd(II), Al(III) and Ga(III)

The chief motive behind this research is the interest provoked by the presence of metal ions as necessary stabilizers of the negative charges of phosphate groups in nucleic acids. The effect that the presence of different metal ions produces on the band principally assigned to the nu(s) PO(3)(2-) mode has been studied using FT-IR and FT-Raman spectroscopy. The results obtained reveal the diagnostic capacity of these techniques in determining the type of metal ion interaction with respect to the mononucleotides that form DNA and RNA, providing a tool for improving the knowledge of the stabilizing or destabilizing effects of these ions on such macromolecules. The metal complexes of the ribonucleotides 5'-CMP and 5'-GMP with Mg(II), Ca(II), Sr(II), Ba(II), Cr(III), Co(II), Cu(II), Zn(II), Cd(II), Al(III) and Ga(III) were obtained in this study. After studying and analyzing the IR and Raman spectra of all these complexes and comparing them with the spectra of the corresponding disodium salts, it was verified that, independently of the type of nucleotide involved, the presence of the metal in the vicinity of the phosphate group produces an alteration in the aforementioned nu(s) PO(3)(2-) band. This effect is related to the type of interaction that the phosphate group has with the metal. Three components are observed: (1) one near 983-975 cm(-1) (detectable in IR and Raman), associated with phosphate groups in an electrostatic type of interaction with the metal ion, separated by two or more water molecules; (2) another near 989-985 cm(-1) (only in IR), associated with phosphate groups in indirect interaction through the water molecules of the coordination sphere of the metal ions; and (3) the IR and Raman bands near 1014-1001 cm(-1), which represent phosphate groups directly bonded to the metal ion. These results are supported by the behavior of 5'-CMP in aqueous solution in the presence of Mg(II) ions.     

Histological and molecular studies of species of Myxobolus Bütschli, 1882 (Myxozoa: Myxosporea) in the gills of Abramis, Blicca and Vimba spp. (Cyprinidae), with the redescription of M. macrocapsularis Reuss, 1906 and M. bliccae Donec & Tozyyakova, 1984

Although Myxobolus spp. from cyprinid fishes are generally characterised by a strict host-specificity, this study has found that the breams Abramis brama (L.), Blicca bjoerkna (L.) and Vimba vimba (L.) may be infected by the same Myxobolus spp. It is demonstrated that M. macrocapsularis Reuss, 1906, a parasite of the gill filaments of B. bjoerkna, can also infect A. brama. In the same way, M. bliccae Donec & Tozyyakova, 1984, also a parasite of B. bjoerkna, can also occur in V. vimba. The molecular sequences of M. macrocapsularis spores from B. bjoerkna and A. brama were 100% identical. Two of the 18S rDNA sequences of three replicate samples of M. bliccae from B. bjoerkna were 100% identical, whereas the third sequence exhibited a 99.7% similarity with sequences from V. vimba. M. bliccae sequences of spores collected from V. vimba showed a 99.8% similarity to the first two isolates and 99.6% to the third. Data obtained by morphological, histological and molecular biological methods all suggest that Myxobolus spp., known for their strict host-specificity, may sometimes infect several closely related cyprinids.     

Compositae of the Guayana Highland—XIII. New combinations in Conyza (Astereae), Praxelis (Eupatorieae), and Riencourtia (Heliantheae) based on names proposed by L.C.M. Richard

The new combinations Conyza laevigata (Astereae), Praxelis diffusa (Eupatorieae), and Riencourtia pedunculosa (Heliantheae) are made. Conyza laevigata includes C. apurensis; Praxelis diffusa includes P. pauciflora and the type of the genus, P. villosa; and Riencourtia pedunculosa includes R. glomerata and R. spiculifera, the type of the genus. Lectotypes are designated for names of five species described by Richard. The current names of other species of Compositae described by Richard in 1792 are given, including the reduction of Eupatorium incisum to Chromolaena odorata. Labeling errors are discussed, and the type of Erigeron laevigatus is taken to be from the West Indies. Riencourtia is newly documented for Bolivia and Panama.     

First Report: Trace Fossil Assemblage Ptychoplasma (P. excelsum,P. vagans), Dendroidichnites (D. irregulare), Ctenopholeus (?C. kutcheri) and Bergaueria (B. hemispherica) in the Cretaceous Rocks of Bagh Formation,Mainland Gujarat,India

Abstract

This report documents the discovery of repichnia trace fossils Ptychoplasma (P. excelsum and P. vagans) and Dendroidichnites (D. irregulare); the fodichnia traces ?Ctenopholeus (?C. kutcheri) and cubichnia traces Bergaueria (B. hemishperica) from silty limestones of the Cretaceous Bagh Formation. These trace fossils have significant implications for the depositional facies and the paleo-environmental interpretations of the Bagh Formation, which have long been debated. Previously identified traces of Protovirgularia were also found in association with the newly discovered trace fossils, indicating the coexistence of both wedge and cleft-foot bivalves. The western area of the mainland Gujarat is known for its abundance and diversity of trace fossils. The trace fossil bearing Cretaceous rocks in the region occur as thin irregular detached patches and linear outcrops. Previous studies documenting trace fossil assemblages from the Bagh Formation characterised them as a combination of dwelling, feeding and locomotion forms, with the stratigraphic unit becoming less fossiliferous westward. Trace fossils in this formation have been studied and described by many workers in the surrounding areas; however, ichnofossils described in this study are new to the Bagh Formation in this area. These trace fossils were observed on recently exposed outcrops along road cuts associated with new road construction from Khasra to Mogra village around Kadipani in Mainland Gujarat.     

Is the enigma a variation? Sagina boydii F. B. White (Caryophyllaceae), Boyd's pearlwort

Sagina boydii F. B. White (Caryophyllaceae), Boyd's pearlwort, is an enigmatic taxon of unknown geographical origin which is only known in cultivation and is of uncertain taxonomic status. Morphological, cytological and geographical evidence suggests that it is most similar to S. procumbens L. and S. saginoides (L.) H. Karst., but it differs in its compact growth form. Genetically, AFLP analysis shows that it can be included as part of the variation in S. procumbens . In cultivation, it will grow true from seed. Other compact growth forms occur in S. procumbens but do not grow true from seed. As S. boydii is part of the variation in S. procumbens , is of uncertain geographical origin, is known only in cultivation, and grows true from seed, it is best treated as a new cultivar, Sagina procumbens 'Boydii'. A neotype and standard specimen is designated.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 147 , 203–211.     

Physical and chemical characteristics of the sediment in the estuarine region of Cananéia (SP), Brazil

Physical and chemical characteristics of sediment were analyzed at eight sampling areas in the estuarine region of Cananéia (SP), Brazil. The samples were collected in 1995 during four periods; summer, autumn, winter and spring. Total nitrogen and phosphorus concentrations, redox potential, water and organic matter percentage, sand and silt percentage and grain size were determined in six different layers of 20 cm deep columns of sediment. In general, the nutrient concentration and the percentage of organic matter decreased with depth and greater variations were observed in the first centimeter of the samples. Differences in nutrient concentration and organic matter were also observed during the study period. The highest concentrations were recorded during the rainy season (February) as a consequence of an accumulation of organic matter brought into the system by rivers and adjacent flooded areas. In general, the sediments had oxidized characteristics until the 5 or 10 cm depth in areas near the rich coastal vegetation. However, in areas open to the ocean, the entire sediment columns were almost completely oxidized.     

Revision of the genus Diclidophora Krøyer, 1838 (Monogenea: Diclidophoridae), with the proposal of Macrouridophora n. g.

The present study re-examines the detailed morphology of the type-species, Diclidophora merlangi (Kuhn, in Nordmann, 1832) Krøyer, 1838, and other Diclidophora species parasitic on gadid fishes: D. denticulata (Olsson, 1876) Price, 1943, D. esmarkii (Th. Scott, 1901) Sproston, 1946, D. luscae (van Beneden & Hesse, 1863) Price, 1943, D. minor (Olsson, 1868) Sproston, 1946, D. palmata (Leuckart, 1830) Diesing, 1850, D. phycidis (Parona & Perugia, 1889) Sproston, 1946, D. pollachii (van Beneden & Hesse, 1863) Price, 1943 and the recently described D. micromesisti Suriano & Martorelli, 1984. An amended generic diagnosis of Diclidophora Krøyer, 1838 (synonym Diclidophora Diesing, 1850) is provided, which includes the presence of a prostatic vesicle in the terminal male genitalia and the distal fusion of the median and peripheral sclerites, a₁ and c₁ in the clamp anterior jaw. Macrouridophora n. g. is herein proposed for species previously considered in Diclidophora, which are parasitic on macrourid and morid fishes. The clamp morphology in Macrouridophora n. g. has distinct lamellate extension attachments to peripheral sclerites c₁ and the distal portion of d₁, with no distal fusion between a₁ and c₁ in the anterior jaw. Macrouridophora macruri (Brinkmann, 1942) n. comb. is chosen as the type-species. Nine other species are herein transferred to Macrouridophora n. g.: M. coelorhynchi (Robinson, 1961) n. comb., M. lotella (Machida, 1972) n. comb., M. nezumiae (Munroe, Campbell & Zwerner, 1981) n. comb. and M. tubiformis (Rohde & Williams, 1987) n. comb. are redescribed, based on the re-examination of type or voucher specimens. Macrouridophora attenuata (Mamaev & Zubtschenko, 1979) n. comb., M. caudata (Mamaev & Zubtschenko, 1984) n. comb., M. papilio (Mamaev & Avdeev, 1981) n. comb., M. paracoelorhynchi (Mamaev & Paruchin, 1979) n. comb. and M. physiculi (Mamaev & Avdeev, 1981) n. comb. have adequately described haptoral clamps in the literature. The clamp morphology in Macrouridophora sp. from Lepidorhynchus denticulatus in Australia is also considered. Diclidophora whitsonii Suriano & Martorelli, 1984 is herein transferred to the genus Macruricotyle Mamaev & Ljadov, 1975, as M. whitsonii (Suriano & Martorelli, 1984) n. comb. D. embiotocae Hanson, 1979 is herein considered a species incertae sedis. D. caudospina Khan & Karyakarte, 1983 and D. paddiforma Deo & Karyakarte, 1979 are herein considered species inquirendae. D. aglandulosa Deo, 1977, D. glandulosa Das, 1972, D. minuta Das, 1972 and D. spindale Deo, 1977 are formally dismissed as nomina nuda. The systematic position of Diclidophora Krøyer, 1838 and Macrouridophora n. g. in the subfamily Diclidophorinae Cerfontaine, 1895 (sensu Mamaev, 1976) is discussed.     

Comparative study of the antitumor effect of two types of murine recombinant interferons, (β) and (γ), against B16-F10 melanoma

Summary A comparative study of the antitumor effect of murine recombinant interferon() Mu-rIFN() and murine recombinant interferon() Mu-rIFN() on B16-F10 melanoma was conducted. Administration of Mu-rIFN() i.p. into C57BL/6 mice on days 1 to 7 produced a higher suppressive effect than Mu-rIFN() both on the growth of s.c. implanted tumor and on the formation of artificial pulmonary metastasis. Pharmacokinetic study of Mu-rIFN() demonstrated that high plasma levels were retained for a long time. In clonogenic assay, Mu-rIFN() at 1000 units/ml showed about 80% inhibition of colonies of B16-F10 melanoma. However, Mu-rIFN() hardly inhibited the colonies, even at 1000 units/ml. Augmentation of natural killer (NK) cytotoxicity was much greater with Mu-rIFN() than Mu-rIFN(), whereas Mu-rIFN() enhanced the cytotoxicity of peritoneal macrophages more strongly than Mu-rIFN(). Injection of Mu-rIFN() i.p. 1 day before tumor challenge also inhibited the formation of pulmonary metastasis of B16-F10 melanoma. However, pretreatment of mice with carrageenan significantly suppressed the inhibitory effect of Mu-rIFN(). From these results, it is suggested that the inhibitory effect of Mu-rIFN() on the tumor growth and metastases of B16-F10 melanoma is mediated partly by direct antitumor effect and partly by the activation of macrophages, and that the augmentation of NK activity contributes mainly to the antitumor effect of Mu-rIFN().     

Cloning and mapping of bovine ZFX gene to the long arm of the X-chromosome (Xq34) and homologous mapping of ZFY gene to the distal region of the short arm of the bovine (Yp13), ovine (Yp12–p13), and caprine (Yp12–p13) Y Chromosome

A part of mouse Zfy-2 sequence was synthesized and used to screen a genomic library of the spinous country-rat (Tokudaia osimensis spp., 2n = 45). An isolated clone had the C-terminal region of Zfy, which consisted of 1190 bp, encoded 336 amino acid residues, and harbored 11 out of 13 zinc finger motifs. With this as a probe, a bovine testis cDNA library was screened. Two ZFX clones were isolated and their sequences combined. The short sequence, lacking part of the 5′ upstream region, was amplified by PCR or RT-PCR, cloned, and sequenced. A full-length ZFX was constructed by combining these three sequences. The bovine ZFX consisted of 5328 bp and encoded 800 amino acid residues, which contained 13 zinc finger motifs. ZFX was used as a probe for fluorescence in situ hybridization and was mapped to Xq34, different from its previously reported site at Xq21-q231. A SINE (short interspersed nuclear element) sequence consisting of 188 bp was found close to the end of the 3′-untranslated region of ZFX. The SINE sequence hybridized to all bovine chromosomes. ZFY is highly homologous with ZFX and, as a result, ZFY could be mapped simultaneously. ZFY was mapped to the distal region of the short arm of the Y Chromosome (Chr) (Yp13), contradicting the previously reported position Yq1. Ovine and caprine ZFY were also mapped with bovine ZFX. Both were mapped to the distal region of the short arm of the Y Chr (Yp12-p13). Ovine ZFX was mapped to a region close to the centromere of the X Chr (Xq13). Received: 23 July 1997 / Accepted: 30 September 1997     

Plastome phylogenomics of Allaeanthus,Broussonetia and Malaisia (Dorstenieae,Moraceae) and the origin of B. × kazinoki

Species of Broussonetia have been essential in the development of papermaking technology. In Japan and Korea, a hybrid between B. monoica and B. papyrifera (= B. × kazinoki) known as kōzo and daknamu is still the major source of raw materials for making traditional paper washi and hanji, respectively. Despite their cultural and practical significance, however, the origin and taxonomy of kōzo and daknamu remain controversial. Additionally, the long-held generic concept of Broussonetia s.l., which included Sect. Allaeanthus and Sect. Broussonetia, was challenged as phylogenetic analyses showed Malaisia is sister to the latter section. To re-examine the taxonomic proposition that recognizes Allaeanthus, Broussonetia, and Malaisia (i.e., Broussonetia alliance), plastome and nuclear ribosomal DNA (nrDNA) sequences of six species of the alliance were assembled. Characterized by the canonical quadripartite structure, genome alignments and contents of the six plastomes (160,121–162,594 bp) are highly conserved, except for the pseudogenization and/or loss of the rpl22 gene. Relationships of the Broussonetia alliance are identical between plastome and nrDNA trees, supporting the maintenance of Malaisia and the resurrection of Allaeanthus. The phylogenomic relationships also indicate that the monoecy in B. monoica is a derived state, possibly resulting from hybridization between the dioecious B. kaempferi (♀) and B. papyrifera (♂). Based on the hypervariable ndhF-rpl32 intergenic spacer selected by sliding window analysis, phylogeographic analysis indicates that B. monoica is the sole maternal parent of B. × kazinoki and that daknamu carries multiple haplotypes, while only one haplotype was detected in kōzo. Because hybridizations between B. monoica and B. papyrifera are unidirectional and have occurred rarely in nature, our data suggest that daknamu might have originated via deliberate hybrid breeding selected for making hanji in Korea. On the contrary, kōzo appears to have a single origin and the possibility of a Korean origin cannot be ruled out.

     

On the plurality of Chydorus sphaericus (O. F. Müller) (Cladocera,Chydoridae), and designation of a neotype from Sjaelsø, Denmark

Two readily distinguishable species of Chydorus sphaericus sens. lat. occur in Salmon Lake, Montana, differing from each other in size and shape of rostrum, headpore configuration, frequency of doubling of teeth on the postabdomen, pattern of reticulation of the shell, and morphology of the mature male, especially the postabdomen, postabdominal claws, copulatory hooks, and rostrum. In any such comparisons, individual specimens are not sufficient; populations are needed to sort out morphological characters associated with instar and sex and character's that change with increasing body size. Comparison of population structure and stage of reproduction can be accomplished by a size-frequency distribution and by specific morphological characters that enable the three male instars to be recognized individually.One species, thought at first to be Chydorus herrmanni, is very close to Chydorus sphaericus sens. str. from Denmark. The other taxon with a short, generally blunt labrum, is described as the new species Chydorus brevilabris. Because of morphological diversity among the entities currently listed as Chydorus sphaericus from around the World, it is certain that a complex of species is represented. To facilitate the eventual resolution of this problem, the population in Sjaelsø, Sjaelland, Denmark has arbitrarily been selected as the standard of comparison, and from this population a neotype and several allotypes have been designated. Cursory examination of various available populations suggests that C. sphaericus sens. str. and C. brevilabris represent a major dichotomy in the sphaericus complex, each branch consisting of an unknown number of closely-related species. Cautions are voiced against assuming that Chydorus sphaericus is a single cosmopolitan and ubiquitous species.This study has been aided by grant GB-29725 for the work in Denmark in 1971–72 and by my present grant DEB 76-20237, both from the National Science Foundation. I am indebted to D. F. Brakke for the samples from Salmon Lake and neighboring localities in Montana and information concerning these localities, and to Brenda J. Hann for dissections and drawings of trunk limbs and help in their interpretation. I am also indebted to Geoffrey Fryer, whose innocent inquiry precipitated this study.     

Molecular phylogenetics of the moth genus Omiodes Guenée (Crambidae: Spilomelinae), and the origins of the Hawaiian lineage

The moth genus Omiodes (Crambidae) comprises about 80 species and has a circumtropical distribution, with the type species, O. humeralis, occurring in Central America. In Hawaii, there are 23 native species currently placed in Omiodes, but this classification has been disputed, and they were previously placed in various other genera. We used molecular phylogenetic analyses to assess the monophyly of Omiodes as a whole, and specifically of the Hawaiian species, as well as their geographic origins and possible ancestral host plants. Mitochondrial (COI) and nuclear (wingless, EF1α, CAD, and RPS5) DNA was sequenced for Omiodes from Hawaii, South America, and Australasia, along with many other putative outgroup spilomeline genera. Phylogenies were estimated using maximum likelihood and Bayesian inference, and various taxon and character datasets. With the exception of two paleotropical species (O. basalticalis and O. odontosticta, whose placement was unresolved) all Hawaiian, paleotropical and neotropical Omiodes, including the type species, fell within a well-supported, monophyletic clade. Although the center of diversity for Omiodes is in the Neotropics, its center of origin was ambiguous, due to poor resolution of the basal splits between paleotropical and neotropical Omiodes. Very low genetic divergence within the Hawaiian Omiodes suggests a relatively recent colonization of the Hawaiian Islands. Phylogenies constructed using all codon positions were poorly resolved at intergeneric levels, and did not reveal a sister taxon for Omiodes, but phylogenies constructed using only first and second codon positions suggested a close relationship with Cnaphalocrocis. The monophyly of several other spilomeline genera is also discussed.     

Stories and photographs of William A. Arnold (1904–2001), a pioneer of photosynthesis and a wonderful friend

William A. Arnold discovered many phenomena in photosynthesis. In 1932, together with Robert Emerson, he provided the first experimental data that led to the concept of a large antenna and a few reaction centers (photosynthetic unit); in 1935, he obtained the minimum quantum requirement of 8–10 for the evolution of one O₂ molecule; in 1951, together with Bernard L. Strehler, he discovered delayed fluorescence (also known as delayed light emission) in photosynthetic systems; and in 1956, together with Helen Sherwood, he discovered thermoluminescence in plants. He is also known for providing a solid-state picture of photosynthesis. Much has been written about him and his research, including many articles in a special issue of Photosynthesis Research (Govindjee et al. (eds.) 1996); and a biography of Arnold, by Govindjee and Srivastava (William Archibald Arnold (1904–2001), 2014), in the Biographical Memoirs of the US National Academy of Sciences, (Washington, DC). Our article here offers a glimpse into the everyday life, through stories and photographs, of this remarkable scientist.     

Depth-dependent reproductive output of the green sea urchin, Strongylocentrotus droebachiensis (O.F. Müller), in relation to the nature and availability of food

Reproductive output of green sea urchins (Strongylocentrotus droebachiensis O.F. Müller) in the field was highest at depths where preferred macro-algae were abundant, and lowest at depths where preferred macro-algae were overgrazed or replaced by non-preferred species (Agarum and Ptilota). Feeding rate and gonad indices of sea urchins in the laboratory were highest on a diet of preferred algae (Fucusdistichus L. subsp. edentatus (Pyl.) Powell, Laminaria longicruris Pyl., Desmarestia spp. and Saccorhizadermatodea (Pyl.) J. Ag.), and lowest on the less preferred Agarum cribrosum (Mert.) Bory, Ptilota serrata Kütz., and crustose corallines. Gamete production/unit area in overgrazed habitats was as great or greater than in kelp beds because of the higher biomass of urchins in overgrazed areas. Gonad weight and reproductive output of urchins from habitats poor in food can be increased by providing preferred foods.     

Aquatic ecosystems of the Yucatán Peninsula (Mexico), Belize, and Guatemala

This study presents limnological and morphological characteristics, physical and chemical properties of waters, and geochemistry of surface sediments for 63 aquatic ecosystems located on the karst Yucatán Peninsula and surrounding areas of Belize and the Guatemalan highlands and eastern lowlands. Our principal goal was to classify the aquatic systems based on their water variables. A principal component analysis (PCA) of the surface water chemistry data showed that a large fraction of the variance (29%) in water chemistry is explained by conductivity and major ion concentrations. The broad conductivity range, from 168 to 55,300 μS cm⁻¹ reflects saline water intrusion affecting coastal aquatic environments, and the steep NW–S precipitation gradient, from ~450 to >3,200 mm year⁻¹. Coastal waterbodies Celestún and Laguna Rosada displayed the highest conductivities. Minimum surface water temperatures of 21.6°C were measured in highland lakes, and warmest temperatures, up to 31.7°C, were recorded in the lowland waterbodies. Most lakes showed thermal stratification during the sampling period, with the exception of some shallow (<10 m) systems. Lakes Chichancanab, Milagros, and Bacalar displayed sulfate-rich waters. Waters of sinkholes had relatively high conductivities (<3,670 μS cm⁻¹) and a broad range of δ¹⁸O values (−4.1 to +3.8‰). Ca, HCO₃, and SO₄ dominated the waters of the lowland lakes, whereas Na was the dominant cation in highland lakes. Coastal aquatic ecosystems were dominated by Na and Cl. Cluster analysis based on surface water variables classified aquatic environments of the lowlands and highlands into three groups: (1) lowland lakes, ponds, wetlands, and coastal waterbodies (2) highland lakes, and (3) sinkholes and rivers. A broad trophic state gradient was recorded, ranging from the eutrophic Lake Amatitlán and the Timul sinkhole to oligotrophic Laguna Ayarza, with the highest water transparency (11.4 m). We used major and trace elements in surface sediments to assess pollution of waterbodies. Lakes Amatitlán, Atescatempa, El Rosario, Cayucón, Chacan-Lara, La Misteriosa, rivers Subín and Río Dulce, the wetland Jamolún, and the sinkhole Petén de Monos showed evidence of pollution and urban development. Their surface sediments displayed high concentrations of As, Cu, Fe, Ni, Pb, Se, Zn, and Zr, which suggest moderate to strong pollution.     

In vitro regeneration of the endangered cactus Turbincarpus mombergeri (Riha), a hybrid of T. laui × T. pseudopectinatus

Turbinicarpus mombergeri is a cacti species formed by a hybridization process between Turbinicarpus laui and Turbinicarpus pseudopectinatus. Under natural conditions, it is very difficult for two species be genetically compatible for hybridization, and to produce flowers at the same time. Thus, T. mombergeri is a very interesting and a rare species. Unfortunately, the current populations are decreasing and now it is considered critically endangered. The aim of this research was to develop a successful protocol for propagating T. mombergeri using the in vitro culture techniques. Seed disinfection was performed with Plant Preservative Mixture, and 80% of germination occurred at day 45 in Murashige-Skoog medium. The shoots were cut longitudinally, and the segments were transferred to media containing 2.22 or 4.44 µM benzyladenine to induce shooting. The generated shoots were highly hydrated, and presented abundant callus. The hyperhydricity was controlled by reducing salt medium concentration, by increasing calcium levels and by using polyethylenglycol. The reduction of callus was attained by adding tri-iodo benzoic acid. Vigorous and thick shoots were generated in medium containing urea, and rooting improved in the presence of 0.5 µM indoleacetic acid. Plantlets with normal morphology were obtained, and the survival rate of the plants in soil was 80%. The methodology developed represents an alternative for propagation of T. mombergeri under controlled conditions for commercial or conservation purposes.

     

Production and cytogenetics of the intergeneric hybrids Brassica juncea×Orychophragmus violaceus and B. carinata×O. violaceus

 Intergeneric hybrids between Brassica juncea (2n=36), B. carinata (2n=34) and Orychophragmus violaceus (2n=24) were produced when B. juncea and B. carinata cultivars were used as female parents. The hybrids between B. juncea and O. violaceus had an intermediate morphology except for petal colour and were partially fertile. The hybrids between B. carinata and O. violaceus had a matroclinous morphology and were nearly fertile. Cytological analysis of the hybrids and their progenies gave the following results. (1) In the hybrids between B. juncea and O. violaceus, the somatic tissues of the roots, leaves and styles were mixoploid (2n=12–42), and cells with 24, 30 or 36 chromosomes were the most frequent. Based on the recorded numbers and behaviour of the mitotic and meiotic chromosomes, complete and partial separation of the parental genomes was proposed to have occurred during mitosis. This resulted in the occurrence of cells with possibly complete and incomplete complements of the parental species and cells with parental complements and some additional chromosomes from the other parent. (2)  Pollen mother cells (PMCs) possibly with both parental chromosome complements, only B. juncea chromosomes or a complete B. juncea complement with additional O. violaceus chromosomes were more competitive in entering meiosis. The majority of fertile gametes were deduced to have been produced by PMCs with a B. juncea complement with or without additional O. violaceus chromosomes. (3) The progeny plants from selfed hybrids between B. juncea and O. violaceus were morphologically either of a B. juncea, hybrid or variable type. Cytologically they were grouped into six types according to the frequencies of cells with various chromosome numbers. All of the plants except 2 which constituted two types, were mixoploids, composed of cells with various chromosome numbers, mainly in a certain serial range. (4) The hybrid plants between B. carinata and O. violaceus were mixoploids with chromosome numbers in the range of 12–34, and cells with 2n=34 were the most frequent. The main categories of PMCs with 17 bivalents at metaphase I and 17 : 17 segregations at anaphase I contributed to the high fertility of the hybrids and the fact that their progeny after selfing were mainly plants with 2n=34. Somatic and meiotic separation of the parental genomes was proposed to have occurred in the hybrids between B. carinata and O. violaceus. (5) Mitotic and meiotic elimination of what could be O. violaceus chromosomes might also have contributed to the observed mitotic and meiotic cell types in the two kinds of hybrids studied. Finally, the possible mechanisms behind these cytological observations and their potential in the production of Brassica aneuploids were discussed. Received: 4 February 1997/Accepted: 29 July 1997     

Characterization and Phylogenetic Relationships of Photorhabdus luminescens subsp. sonorensis (γ-Proteobacteria: Enterobacteriaceae), the Bacterial Symbiont of the Entomopathogenic Nematode Heterorhabditis sonorensis (Nematoda: Heterorhabditidae)

Photorhabdus are motile Gram-negative bacteria that have a mutualistic association with Heterorhabditis nematodes (Heterorhabditidae). These bacteria possess peculiar biochemical characteristics such as inability to reduce nitrates, and the capacity to ferment only a limited number of carbohydrates. Heterorhabditis nematodes vector the bacteria from one insect host to another and also provide shelter to the bacteria from soil stressors and antagonists. Once inside the insect host, the bacterial symbionts are released and produce toxins and secondary metabolites and broad-spectrum antibiotics, which kill the host by septicemia within 48 h. At present, three Photorhabdus spp. have been identified: P. luminescens, P. temperata, and P. asymbiotica, and many subspecies have also been described. Characterization of new species and subspecies has been based on sequence data, mostly of the 16S rDNA, and also of a selection of protein coding genes. In addition to this, phenotypic traits including temperature growth, colony morphology, color, light production, carbohydrate response, and assimilation, among others, have been considered. In this study, we characterize the bacterial symbiont of Heterorbabditis sonorensis, a recently discovered entomopathogenic nematode species form the Sonoran desert in Arizona, USA. A selection of classic biochemical and molecular methods including sequence data of six genes: 16s rDNA, and four protein coding genes: gyrB, recA, gltX, and dnaN were considered. Evolutionary relationships of this new Photorhabdus subsp. were inferred considering maximum parsimony and Bayesian analyses.