High chromosome numbers in Mojavean and Sonoran desert Atriplex canescens (Chenopodiaceae)

Cytological, flavonoid, and morphological data are provided for several varieties of the shrubby species Atriplex canescens (Pursh) Nutt. (x = 9) (fourwing saltbush) in the Mojavean and Sonoran deserts of southwestern United States and northern Mexico. These include var. linearis (S. Wats.) Munz (2x); var. angustifolia (Torr.) S. Wats. (2x, 4x); var. occidentalis (Torr. & Frem.) Welsh & Stutz (4x, 6x), the common variety; var. laciniata Parish (12x); and var. macilenta Jeps. (12x). Atriplex canescens var. grandidentatum Stutz & Sanderson (20x) is newly described. An autoploid origin from 12x var. laciniata is suggested for the 14x and 20x polyploids, through unreduced gametes. Founder populations of odd-ploid products arising during such a sequence of events could probably have returned to even-ploidy through genetic segregation and the rapid elimination of aneuploids. Morphological characters suggest an origin for 12x var. laciniata by interspecific hybridization of var. occidentalis with A. polycarpa (Torr.) S. Wats.     

Micropropagation of Cowania subintegra and Cowania stansburiana

Both Cowania subintegra Kearney and C. stansburiana Torr. were successfully propagated in vitro. Shoot proliferation occurred from shoot tips of green-house grown C. subintegra using a modified Murashige and Skoog medium supplemented with 4.4 M 6-benzyladenine and 0.5 M indole butyric acid. Excised microshoots (1.5–3.0 cm long) of both species were rooted using a two-step process in which they were cultured for 3 days in a root initiation medium with 2.7 M naphthaleneacetic acid and then transferred to a low nitrogen root elongation medium without auxin. Plantlets were successfully transferred to soilless potting mix.     

Vertically stratified frugivore community composition and interaction frequency in a liana fruiting across forest strata

Vertical stratification is a key feature of tropical forests and structures plant–frugivore interactions. However, it is unclear whether vertical differences in plant-frugivore interactions are due to differences among strata in plant community composition or inherent preferences of frugivores for specific strata. To test this, we observed fruit removal of a diverse frugivore community on the liana Marcgravia longifolia in a Peruvian rain forest. Unlike most other plants, Marcgravia longifolia produces fruits across forest strata. This enabled us to study effects of vertical stratification on fruit removal without confounding effects of plant species and stratum. We found a high number of visits of a few frugivore species in the understorey and a low number of visits of many different frugivores in the canopy and midstorey. Whereas partial and opportunistic frugivores foraged across strata with differing frequencies, obligate frugivores were only found eating fruits in the higher strata. Avian frugivores foraging in the canopy were mainly large species with pointed wings, whereas under- and midstorey avian foragers were smaller with rounded wings. Our findings suggest a continuous shift in the frugivore community composition along the vertical gradient, from a few generalized frugivores in the understorey to a diverse set of specialized frugivores in the canopy. This shift in the frugivore community leads to correlated, reciprocal changes from specialized to generalized plant-frugivore interactions. Thus, we conclude that vertical niche differentiation between species in tropical forests persists even when food resources are available across strata. This highlights its role for promoting biodiversity and ecosystem functioning.     

Morphological parameters affecting false lumen thrombosis following type B aortic dissection: a systematic study based on simulations of idealized models

Type B aortic dissection (TBAD) carries a high risk of complications, particularly with a partially thrombosed or patent false lumen (FL). Therefore, uncovering the risk factors leading to FL thrombosis is crucial to identify high-risk patients. Although studies have shown that morphological parameters of the dissected aorta are related to FL thrombosis, often conflicting results have been reported. We show that recent models of thrombus evolution in combination with sensitivity analysis methods can provide valuable insights into how combinations of morphological parameters affect the prospect of FL thrombosis. Based on clinical data, an idealized geometry of a TBAD is generated and parameterized. After implementing the thrombus model in computational fluid dynamics simulations, a global sensitivity analysis for selected morphological parameters is performed. We then introduce dimensionless morphological parameters to scale the results to individual patients. The sensitivity analysis demonstrates that the most sensitive parameters influencing FL thrombosis are the FL diameter and the size and location of intimal tears. A higher risk of partial thrombosis is observed when the FL diameter is larger than the true lumen diameter. Reducing the ratio of the distal to proximal tear size increases the risk of FL patency. In summary, these parameters play a dominant role in classifying morphologies into patent, partially thrombosed, and fully thrombosed FL. In this study, we point out the predictive role of morphological parameters for FL thrombosis in TBAD and show that the results are in good agreement with available clinical studies.

     

Cloning of the amphibolic Calvin cycle/OPPP enzyme d-ribulose-5-phosphate 3-epimerase (EC 5.1.3.1) from spinach chloroplasts: functional and evolutionary aspects

Exploiting the differential expression of genes for Calvin cycle enzymes in bundle-sheath and mesophyll cells of the C4 plant Sorghum bicolor L., we isolated via subtractive hybridization a molecular probe for the Calvin cycle enzyme d-ribulose-5-phosphate 3-epimerase (R5P3E) (EC 5.1.3.1), with the help of which several full-size cDNAs were isolated from spinach. Functional identity of the encoded mature subunit was shown by R5P3E activity found in affinity-purified glutatione S-transferase fusions expressed in Escherichia coli and by three-fold increase of R5P3E activity upon induction of E. coli overexpressing the spinach subunit under the control of the bacteriophage T₇ promoter, demonstrating that we have cloned the first functional ribulose-5-phosphate 3-epimerase from any eukaryotic source. The chloroplast enzyme from spinach shares about 50% amino acid identity with its homologues from the Calvin cycle operons of the autotrophic purple bacteria Alcaligenes eutrophus and Rhodospirillum rubrum. A R5P3E-related eubacterial gene family was identified which arose through ancient duplications in prokaryotic chromosomes, three R5P3E-related genes of yet unknown function have persisted to the present within the E. coli genome. A gene phylogeny reveals that spinach R5P3E is more similar to eubacterial homologues than to the yeast sequence, suggesting a eubacterial origin for this plant nuclear gene.Abbreviations R5P3E d-ribulose-5-phosphate 3-epimerase - RPI ribose-5-phosphate isomerase - TKL transketolase - PRK phosphoribulokinase - GAPDH glyceraldehyde-3-phosphate dehydrogenase - FBP fructose-1,6-bisphophatase - FBP fructose 1,6-bisphosphate - G6PDH glucose-6-phosphate dehydrogenase - 6PGDH 6-phosphogluconate dehydrogenase - OPPP oxidative pentose phosphate pathway - Rubisco ribulose-1,5-bisphosphate carboxylase/oxygenase - FBA fructose-1,6-bisphophate aldolase - IPTG isopropyl -d-thiogalactoside - GST glutathione S-tranferase - PBS phosphate-buffered saline - TPI triosephosphate isomerase     

Zur Nahrungs?kologie des Wei?storchs (Ciconia ciconia) in Oberschwaben: Beobachtungen an zwei Paaren

Zusammenfassung Das Nahrungssuchverhalten zweier Weißstorch-Paare wurde durch systematische Beobachtung der Störche im Gelände erfaßt. Das Storchenpaar mit gutem Grünlandangebot in der Nähe des Nestes und kleiner Jungenzahl hatte während der ganzen Brutsaison viel Freizeit. Es suchte in einem Entfernungsbereich bis 1,5 km vom Nest Futter und wandte fast ausschließlich die profitable Mäusejagd an. Das Storchenpaar mit schlechtem Grünlandangebot in der Nähe des Nestes und relative großer Jungenzahl nutzte während der Jungenaufzucht einen Großteil der Helligkeitsperiode zur Futtersuche. Es dehnte dabei seinen Entfernungsbereich bis 3,8 km vom Nest aus und ging bei gutem Regenwurmangebot in nahen Entfernungen zum Nest auch der unprofitablen Regenwurmjagd nach. Die Nahrungsaufnahme der Störche betrug während der Brutphase etwa 2600 kJ, während der Aufzucht von ein bis zwei Jungen ungefähr 8850 kJ pro Storch und Tag.

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On the feeding ecology of the White stork (Ciconia ciconia) in Obserschwaben (Baden-Württemberg, Germany): observations on two pairs

Summary The foraging behaviour of two pairs of White storks was recorded by rigorous observations in the field. One pair of storks, with many meadows in the vicinity of their nest and a small clutch size, spent much time resting throughout the breeding season. They searched for food within a range of 1.5 km from the nest and used the profitable mouse hunting method almost exclusively. When rearing its young, the other pair of storks, with few meadows in the vicinity of their nest and a relatively large clutch size, used a large part of the daylight period for foraging. Thus they expanded their range up to 3.8 km from the nest. When earthworms were abundant, they also used the unprofitable earthworm hunting method within short distances from the nest. The daily energy intake per stork during incubation was approximately 2600 kJ, and approximately 8850 kJ when rearing young.

     

Effect of temperature cycling on the production of aflatoxin by Asperfillus parasiticus.

Aspergillus parasiticus (NRRL 2999) was grown under cycling temperature conditions on rice and nutmeat substrates. Under conditions of diurnal and nocturnal time-temperature sequencing, total heat input is an important factor of toxin production. When expressed in degree hours per day, thermal input becomes more definitive and provides a finite number, which can be related to observable changes in the culture such as sporulation and toxin biosynthesis. Three well-defined levels of response were observed in relation to heat input: no growth was detected at thermal inputs of less than 208 degree hours/day; mycelial growth as well as copious amounts of an orange pigment were observed at thermal inputs between 208 and 270 degree hours/day; sporulation and aflatoxin biosynthesis occurred above 270 degree hours/day. Between the optimum and minimum thermal input, cycling temperatures significantly reduced the period of the trophophase over cultures receiving equal heat input at a constant rate. Cycling temperatures at the low and high extremes of the temperature range had little or no effect upon the growth pattern of the culture. Regardless of how temperature was manipulated, these responses were consistent with the heat input received by the culture. A. parasiticus did not compete well when mixed with natural fungal isolates from nutmeats and was easily overgrown by the wild isolates even at relatively high thermal input and when present in superior numbers. This factor and heat input generally below that required for toxin biogenesis at harvest time appear to be two significant factors that limit occurrence of aflatoxin on nut crops of the Willamette Valley. These factors are likely to have significance for other crops grown and harvested under similar circumstances.     

IL-28A,IL-28B,and IL-29: Promising cytokines with type I interferon-like properties

IL-28A, IL-28B and IL-29 (also designated type III interferons) constitute a new subfamily within the IL-10–interferon family. They are produced by virtually any nucleated cell type, particularly dendritic cells, following viral infection or activation with bacterial components, and mediate their effects via the IL-28R1/IL-10R2 receptor complex. Although IL-28/IL-29 are closer to the IL-10-related cytokines in terms of gene structure, protein structure, and receptor usage, they display type I interferon-like anti-viral and cytostatic activities. Unlike type I interferons, the target cell populations of IL-28/IL-29 are restricted and mainly include epithelial cells and hepatocytes. These properties suggest that IL-28/IL-29 are potential therapeutic alternatives to type I interferons in terms of viral infections and tumors. This review describes the current knowledge about these cytokines.     

Scale‐down simulators for mammalian cell culture as tools to access the impact of inhomogeneities occurring in large‐scale bioreactors

During the scale‐up of a bioprocess, not all characteristics of the process can be kept constant throughout the different scales. This typically results in increased mixing times with increasing reactor volumes. The poor mixing leads in turn to the formation of concentration gradients throughout the reactor and exposes cells to varying external conditions based on their location in the bioreactor. This can affect process performance and complicate process scale‐up. Scale‐down simulators, which aim at replicating the large‐scale environment, expose the cells to changing environmental conditions. This has the potential to reveal adaptation mechanisms, which cells are using to adjust to rapidly fluctuating environmental conditions and can identify possible root causes for difficulties maintaining similar process performance at different scales. This understanding is of utmost importance in process validation. Additionally, these simulators also have the potential to be used for selecting cells, which are most robust when encountering changing extracellular conditions. The aim of this review is to summarize recent work in this interesting and promising area with the focus on mammalian bioprocesses, since microbial processes have been extensively reviewed.