The effect of 8 days of microgravity on regeneration of intact plants from protoplasts

The growth and development of protoplasts of rapeseed (Brassica napus L. cv Line) and carrot (Daucus carota L. cv. Navona) were studied onboard the Space Shuttle‘Discovery’during an 8-day International Microgravity Laboratory [IML-l) mission in January 1992. The Flight experiments were carried out in‘Biorack'. a fully controlled cell biological experimental facility. under microgravity conditions and in a l-g centrifuge. Parallel experiments were performed in a‘Biorack’module on the ground. After retrieval, some samples were subcultured on appropriate media and analysed for callus growth and regeneration to intact plants. The remainder were used for biochemical analysis. Samples fixed on board the Space Shuttle were kept in l% glutaraldehyde fixative at 4°C for 3–7 days for microscopy analysis after retrieval. Protoplasts exposed to microgravity conditions showed a delay in cell wall synthesis. Cells were swollen in appearance and formed cell aggregates with only few cells. Callus were obtained from protoplasts cultured under microgravity (Fogl). on the l-g centrifuge on board the shuttle (Flg), under normal l-g conditions on the ground (G1g) and on a centrifuge on the ground giving 1.4 g (Gl.4g). Regeneration of intact rapeseed plants was obtained from Flg. Glg and G1.4g. However, no plants were regenerated from protoplasts exposed to microgravity (Fog). Biochemical analysis indicated that the microgravity samples (Fog displayed a reduced packed cell volume, an increased concentration of soluble proteins per cell, and a reduced specific activity of peroxidase in the cytoplasm. Morphometric analysis of fixed samples demonstrated that 3-day old protoplasts under microgravity conditions were significantly larger than protoplasts kept on the l-g centrifuge in space. UItrastructural analysis by transmission electron microscopy showed that protoplasts exposed to microgravity conditions for 3 days had larger vacuoles and a slightly reduced starch content compared to Flg cells. Cell aggregates formed under microgravity conditions (Fog) had an average of 2–I cells per aggregate while aggregates formed under Flg had 8–12 cells.     

A new 2D NMR method for measurement of JHH coupling constants

Summary A new 2D NMR pulse sequence for E.COSY-type measurement of J_HH coupling constants is introduced. It exploits a heteronuclear spin, e.g., ¹³C, for displacement in the ₁ frequency dimension via a large heteronuclear J coupling. The experiment is demonstrated by application to a heptapeptide at the natural abundance ¹³C level. It is suitable, for example, for measurement of ³J_HH and ⁴J_HH coupling constants in peptides and proteins.     

Evidence for (PNA)2/DNA triplex structure upon binding of PNA to dsDNA by strand displacement

The binding of PNA (peptide nucleic acid) T₂CT₂CT₄-LysNH₂ to the double-stranded DNA target 5′ -A₂GA₂GA₄ was studied by KMnO₄ and dimethylsulfate (DMS) probing. It is found that upon sequence-specific strand displacement binding of the PNA to the dsDNA target concomitant protection of the N-7 of guanines within the target takes place. It is furthermore shown that the binding of this PNA is more efficient at pH 5.5 that at pH 6.5 and very inefficient at pH 7.5. These results clearly indicate that C⁺G Hoogsteen base pairing is present and important for binding and that the strand displacement complex therefore involves a PNA·DNA-PNA triplex.     

Analysen epigenetischer Marker aus Liquid Biopsies: Informationen von jenseits des Genoms

Analysis of epigenetic markers from liquid biopsies provides insights into physiological and pathological processes in the body of a person far beyond the pure sequence information. In particular, the DNA methylation pattern and the expression patterns of mRNA and ncRNA are accessible from liquid biopsies. Therefore, a whole group of new potential biomarkers will come into reach for non-invasive and economic diagnostics. Furthermore, and in contrast to the pure DNA sequence analysis from liquid biopsies, the high tissue specificity of several epigenetic markers allows the origin of the nucleic acids analyzed, e.?g. with regard to the affected organ, to be determined. In view of the falling costs of sequencing and the technological progress that continues to push the detection limits to even more sensitive application, epigenetic analyses from liquid biopsies could further enforce the trend toward precision medicine.     

Phylogeny of the Alismatales (Monocotyledons) and the relationship of Acorus (Acorales?)

A phylogenetic analysis of the early branching lineages of the monocotyledons is performed using data from two plastid genes (rbcL and matK), five mitochondrial genes (atp1, ccmB, cob, mttB and nad5) and morphology. The complete matrix includes 93 terminals representing Acorus, the 14 families currently recognized within Alismatales, and numerous lineages of monocotyledons and other angiosperms. Total evidence analysis results in an almost completely resolved strict consensus tree, but all data partitions, genomic as well as morphological, are incongruent. The effects of RNA editing and potentially processed paralogous sequences are explored and discussed. Despite a decrease in incongruence length differences after exclusion of edited sites, the major data partitions remain significantly incongruent. The 14 families of Alismatales are all found to be monophyletic, but Acorus is found to be included in Alismatales rather than being the sister group to all other monocotyledons. The placement is strongly supported by the mitochondrial data, atp1 in particular, but it cannot be explained as an artifact caused by patterns of editing or by sampling of processed paralogues.     

Leaf gas films,underwater photosynthesis and plant species distributions in a flood gradient

Traits for survival during flooding of terrestrial plants include stimulation or inhibition of shoot elongation, aerenchyma formation and efficient gas exchange. Leaf gas films form on superhydrophobic cuticles during submergence and enhance underwater gas exchange. The main hypothesis tested was that the presence of leaf gas films influences the distribution of plant species along a natural flood gradient. We conducted laboratory experiments and field observations on species distributed along a natural flood gradient. We measured presence or absence of leaf gas films and specific leaf area of 95 species. We also measured, gas film retention time during submergence and underwater net photosynthesis and dark respiration of 25 target species. The presence of a leaf gas film was inversely correlated to flood frequency and duration and reached a maximum value of 80% of the species in the rarely flooded locations. This relationship was primarily driven by grasses that all, independently of their field location along the flood gradient, possess gas films when submerged. Although the present study and earlier experiments have shown that leaf gas films enhance gas exchange of submerged plants, the ability of species to form leaf gas films did not show the hypothesized relationship with species composition along the flood gradient.     

Knowledge Loss and Change Between 2002 and 2017—a Revisit of Plant Use of the Maasai of Sekenani Valley,Maasai Mara,Kenya

Traditional plant use is of tremendous importance in many societies, including most rural African communities. A variety of studies have shown knowledge dwindling due to changes towards a more Western lifestyle, and the influence of modern tourism. In the case of the Sekenani Maasai, we hypothesized in 2006 that, while little knowledge loss had been observed at that time, the change from a nomadic to a more sedentary lifestyle would lead to an accelerating loss of traditional plant knowledge. This paper examines the plant use of the Maasai in the Sekenani Valley, North of the Maasai Mara National Reserve 15 years after a first study. Based on the study of 2002 (Bussmann et al. Journal of Ethnobiology and Ethnomedicine 2: 22, 2006), semi-structured interviews were conducted with staff of Sekenani Camp in order to document current plant knowledge. The results of this follow-up study indicate dramatic knowledge loss over the last 15 years. Of 139 used species documented in 2002, only 84 remained in use in 2017. Off those species still in use, 30 had experienced a loss of uses, while for 18 species new uses were documented. The knowledge loss observed in Sekenani in 15 years is rather dramatic. Lifestyle changes and over-use of resources have clearly led to a rapid decline of traditional knowledge on plant use. This trend is expected to continue.     

Trends in breeding phenology across ten decades show varying adjustments to environmental changes in four wader species

Capsule: During 1928–2016, initiation of egg-laying advanced in two wader species, remained unchanged in one, and was delayed in one species. The changes across years and variation among species can be explained by climatic variables and differences in migratory strategies.

Aims: To document possible changes in initiation of egg-laying in common Danish wader species since the early part of the 20th century and seek possible correlations between egg-laying, timing of arrival and environmental factors.

Methods: Annual records of the first eggs and chicks found on the scientific reserve of Tipperne in western Denmark 1928–2016 were analysed using linear regression to determine patterns in timing of egg-laying, pre-breeding length and influence of climate factors.

Results: Two short/medium-distance migrant wader species, Northern Lapwing Vanellus vanellus and Common Redshank Tringa totanus advanced breeding initiation by about one week, with winter North Atlantic oscillation Index and spring temperature as important predictors. By contrast, two long-distance migrants, Black-tailed Godwit Limosa limosa and Ruff Calidris pugnax, did not advance egg-laying, and Ruff actually delaying it. As a result, the pre-laying period was significantly prolonged in both Black-tailed Godwit (21 days) and Ruff (52 days), while there was no significant change for Common Redshank.

Conclusion: Long-distance migrants are able to adjust spring arrival but unlike short/medium-distance migrants, do not necessarily adjust breeding initiation.     

On the relation between dry matter and volume of bacteria

Dry matter and volumes of 337 individual bacterial cells with volumes in the range 0.01–7m³ from different origins were measured. An allometric relation was established between dry matter and volume, such that smaller bacteria tended to have a higher dry matter to volume ratio than larger bacteria. The results are compared to results from similar work on algae. The implications for the use of conversion factors are discussed.