Reassessing Neotropical angiosperm distribution patterns based on monographic data: a geometric interpolation approach

Monographic data rely on specimens deposited in herbaria and museums, which have been thoroughly revised by experts. However, monographic data have been rarely used to map species richness at large scale, mainly because of the difficulties caused by spatially heterogeneous sampling effort. In this paper we estimate patterns of species richness and narrow endemism, based on monographic data of 4,055 Neotropical angiosperm species. We propose a geometric interpolation method to derive species ranges at a 1° grid resolution. To this we apply an inverse distance-weighted summation scheme to derive maps of species richness and endemism. In the latter we also adjust for heterogeneous sampling effort. Finally, we test the robustness of the interpolated species ranges and derived species richness by applying the same method but using a leave-one-out-cross-validation (LOOCV). The derived map shows four distinct regions of elevated species richness: (1) Central America, (2) the Northern Andes, (3) Amazonia and (4) the Brazilian Atlantic coast (‘Mata Atlantica’). The region with the highest estimated species richness is Amazonia, with Central America following closely behind. Centers of narrow endemism are located over the entire Neotropics, several of them coinciding with regions of elevated species richness. Sampling effort has a minor influence on the interpolation of overall species richness, but it substantially influences the estimation of regions of narrow endemism. Thus, in order to improve maps of narrow endemism and resulting conservation efforts, more collection and identification activity is required.     

Leydig cell mitoses in human testes bearing early germ cell tumors

Summary Numerous mitoses were noted in testicular tissue from adult men with early germ cell tumors. More than 15 Leydig cells undergoing mitosis were found in the interstitial compartment. The presence of specific crystalline intracytoplasmatic inclusions demonstrated for the first time that differentiated Leydig cells are capable of proliferation. Occasionally cells are difficult to discriminate during mitosis. To establish reference criteria, the light- and electron-microscopic features of the following mitotic cells were examined: Leydig cells, fibroblasts, perivascular cells, peritubular cells, and lymphocytes. Supplementary mitoses in germ cell tumors and in a case of Leydig cell tumor were investigated. In the literature, only single reports of mitoses in Leydig cells are available. The frequent incidence of Leydig cell mitosis in early germ cell tumors may be due to the presence of growth-promoting factors in the testicular tissue.     

Morphology and structural organization of Haller's organ during postembryonic development ofArgas (Persicargas) walkerae (Ixodoidea: Argasidae)

Scanning-electron-microscopic investigations of Haller's organ in larvae, nymphs I, II, III and IV, and male and female adultArgas (Persicargas) walkerae ticks showed that morphology and structural organization change during postembryonic development. Stage-dependent differences existed regarding setal numbers of the anterior pit as well as formation and reticulation of cuticular projections in the capsule cavity. The anterior pit increased in size in the course of postembryonic development. It contained only seven setae in larvae, one conical, setiform and grooved seta each as well as two porose and fine setae. Nymphs I, II, III and IV and adult ticks had equal numbers of setae; however, one additional unilaterally serrate and grooved seta each were present. Setal length increased continuously during postembryonic development and attained maximum values in adult ticks. The capsule consisted of roof and cavity and was located distinctly lateral in larvae, slightly lateral in nymphs I and II, and in all other stages directly on the longitudinal axis of tarsus. The capsule roof showed a reticular structure. The slit-like main aperture was located peripherally and arranged transversally to the longitudinal axis of tarsus I in larvae. Nymphs and adult ticks had a central, circular main aperture. Stage-dependent cuticular projections of varying form protruded into the capsule cavity. Larvae had only single, free-standing projections which ramified slightly and communicated with each other. Projections were more heavily reticulated in nymphs I and II. In nymphs III and IV as well as male and female adult ticks, a long centrally situated tube of reticular appearance was seen, which was supported by a large number of radially organized and interlocking pillars and communicated with the capsule roof. In all tick stages there were always four porose setae present, arranged on the capsule floor.     

Expression of the core antigen gene of hepatitis B virus (HBV) in Acetobacter methanolicus using broad-host-range vectors

Summary Using the broad-host-range promoter probe vector pRS201 for cloning of phage Acm1 promoters, we established a convenient vector system for expression of heterologous genes in different Gram-negative bacteria. The usefulness of this system was demonstrated by expression of the HBV core gene in Acetobacter methanolicus. Plasmids carrying the HBV core gene downstream of different Acm1-phage promoters were transferred to A. methanolicus, a new potential host for recombinant DNA expression. Using enzyme immunoassay and immunoblot techniques, the amount and composition of core antigen produced in A. methanolicus were compared with that derived from Escherichia coli. The expression of immunoreactive core antigen in A. methanolicus exceeds by sevenfold that in E. coli using an expression system with tandemly arranged promoters. Morphological observations by electron microscopy show that the HBV core gene products isolated from both hosts are assembled into regular spherical particles with a diameter of about 28 nm that are comparable to original viral nucleocapsids. Offprint requests to: R. Schröder     

Transfer and Expression of Lithoautotrophy and Denitrification in a Host Lacking These Metabolic Activities

The conjugative 450-kilobase-pair megaplasmid pHG1 from Alcaligenes eutrophus H16 was transferred to the herbicide-degrading soil bacterium A. eutrophus JMP134. This transfer was achieved by means of RP4 mobilization and a Tn5-Mob insertion provided in trans on the megaplasmid replicon. Although kanamycin-resistant transconjugants also occurred with other gram-negative species such as Rhizobium, Agrobacterium, and thiobacteria, A. eutrophus JMP134 was the only recipient which stably maintained the megaplasmid. pHG1-containing transconjugants derived from JMP134 expressed all metabolic functions associated with the plasmid: the ability to oxidize hydrogen through catalysis of two hydrogenases, to assimilate carbon dioxide via the Calvin cycle pathway, and to grow with nitrate anaerobically. All of these metabolic activities were absent in the original strain JMP134.     

Late enzymes of vindoline biosynthesis. Acetyl-CoA: 17-O-deacetylvindoline 17-O-acetyl-transferase

From differentiated plants of Catharanthus roseus (L.) G. Don, a specific enzyme was isolated and named acetyl-CoA : 17-O-deacetylvindoline 17-O-acetyltransferase, acting on the biosynthetic formation of the Aspidosperma type alkaloid vindoline.The enzyme shows a high selectivity towards different substrates. The acetyl-CoA-dependent transferase also catalyses the reverse reaction by hydrolysis of the 17-O-acetyl group of vindoline in the presence of free CoA. This enzyme is localized only in vindoline-containing plant parts, but was so far not detectable in cell suspension cultures of C. roseus. The enzyme allows the synthesis of labelled vindoline with high specific activity, applicable for instance as tracer for radioimmunoassays of vindoline.     

Development of flower buds in thin-layer cultures of floral stalk tissue from tobacco: Role of hormones in different stages

The in vitro development of flower buds was studied on tissue explants of epidermis and subepidermal cortex from the flower stalks of Nicotiana tabacum L. cv. Samsun. The number of flower buds formed depended mainly on cytokinin concentration. Auxin acted as a modifier in a complex way. In early development, NAA at 1 μ M decreased the number of buds initiated and delayed bud emergence. At a later stage, auxin promoted bud outgrowth at the same concentration. Optimal results were obtained when explants were first incubated at low auxin concentration for 3–5 days and subsequently transferred to an elevated auxin level. Physiological processes that lead to flower bud initiation start very soon after the onset of incubation. This was inferred from experiments whereby explants were first cultured at an inductive cytokinin concentration and then transferred to a non-inductive hormone level.     

Mapping of cysteine genes on the chromosome of Pseudomonas aeruginosa PAO

Summary Three loci coding for different steps in the pathway of cysteine biosynthesis have been mapped by R68.45-mediated coconjugation analysis. The cysteine auxotrophic mutants could be subdivided into sulfite and sulfide-requiring mutants. Sulfide-requiring mutants (cysIV group) were localized at a single position between pyrF and pur-67, while sulfite-requiring mutants (cysI and cysII) mapped at two different regions. The cysI group was also localized between pyrF and pur-67, although more distal to pyrF than the cysIV group. This group included the cys-54 marker, which has been mapped previously. The second group of sulfite-requiring mutants, designated as cysII, was cotransducible with hisI and localized at the end of the PAO chromosomal map. This location was also confirmed for the marker cys-59.The marker cys-59 (which was cotransducible with his1) was cotransferred by R68.45-mediated conjugations with both the late marker pur-67 and the early marker ilv-226. As the late marker hisI was positioned at about 60–65 min (Herrmann and Günther, in press) the length of the PAO chromosome was estimated to be about 70 min.     

Untersuchungen zur Trinkwasservaccination gegen Newcastle Disease beim Birkwild (Lyrurus tetrix L., 1758)

European Journal of Wildlife Research - Bei 30 Birkhühnern wurde nach kontrolliert durchgeführter Trinkwasservaccination gegen Newcastle Disease (ND) (Erstimpfung mit Hitchner B1,...