Stability and instability processes in the calli of Fagopyrum tataricum that have different morphogenic potentials

Plant Cell, Tissue and Organ Culture (PCTOC) - The morphogenic callus (MC) of Fagopyrum tataricum contains a large amount of flavonoids, especially rutin, and exhibits a high level of antioxidant...     

A comparison of genetic stability in tea [Camellia sinensis (L.) Kuntze] plantlets derived from callus with plantlets from long-term in vitro propagation

Plant Cell, Tissue and Organ Culture (PCTOC) - The development of tissue-specific or inducible promoters is important for plant genetic engineering. In this study, we isolated two novel promoters...     

Do alternative reproductive strategies in the Wellington tree weta represent different behavioural types?

In many animal species, variation in reproductive success among individuals has led to the evolution of alternative mating strategies, which in the case of insects can often be correlated with developmental trajectories. In the Wellington tree weta, Hemideina crassidens, males can mature at the 8th, 9th or 10th instar, while females mature at the 10th instar only. A number of morphological attributes including male head and mandible size correlate with final instar number, and as these attributes represent a form of weaponry, they are often used in mate/site guarding and male–male competition. Tenth instar males have larger head/mandible/body sizes and show a conventional (guarder) reproductive strategy, whereas smaller 8th instar males typically show an unconventional (sneaker) strategy. In contrast, 9th instar males are predicted to adopt a “jack‐of‐all‐trades” strategy whereby they can fight or sneak depending context. Here, we tested whether alternative reproductive morphs exhibit strategy‐specific differences in risk‐taking associated with refuge emergence, activity and antipredator behaviour and further, whether these traits correlate to form a behavioural syndrome. We found that tree weta show consistent and repeatable differences in activity and refuge use at the individual level; however, behavioural covariances suggest that only 8th instar males exhibit a behavioural syndrome. That 9th instar males show high plasticity and variance in their gallery‐related behaviours supports the hypothesis that these males are a “jack‐of‐all‐trades.” Contrary to our predictions, antipredator behaviour was not correlated with other traits, and differences in behaviour overall were consistently more pronounced between individuals rather than between male morphs or sexes.     

Follicular competition in cows: the selection of dominant follicles as a synergistic effect

Journal of Mathematical Biology - The reproductive cycle of mono-ovulatory species such as cows or humans is known to show two or more waves of follicular growth and decline between two successive...     

Assessment of chemical-crosslink-assisted protein structure modeling in CASP13

With the advance of experimental procedures obtaining chemical crosslinking information is becoming a fast and routine practice. Information on crosslinks can greatly enhance the accuracy of protein structure modeling. Here, we review the current state of the art in modeling protein structures with the assistance of experimentally determined chemical crosslinks within the framework of the 13th meeting of Critical Assessment of Structure Prediction approaches. This largest-to-date blind assessment reveals benefits of using data assistance in difficult to model protein structure prediction cases. However, in a broader context, it also suggests that with the unprecedented advance in accuracy to predict contacts in recent years, experimental crosslinks will be useful only if their specificity and accuracy further improved and they are better integrated into computational workflows.     

A phylogenetic study of krill (Crustacea: Euphausiacea) reveals new taxa and co-evolution of morphological characters

The first comprehensive phylogenetic study of Euphausiacea (all 86 valid species) is presented. It is based on four molecular markers and 168 morphological characters (including 58 characters of the petasma). Phylogenetic analyses support the monophyly and robustness of the families Bentheuphausidae and Euphausiidae and reveal three major clades for which we erect three new subfamilies: Thysanopodinae, Euphausiinae and Nematoscelinae. All genus-level clades are statistically supported (except Thysanopoda in molecular analyses), deeply nested within the subfamily-level clades, and encompass 14 new species groups. Copulatory structures have a major impact on tree topology in the morphological analysis, the removal of which resulted in only half the number of supported clades and genera. We revealed three groups of morphological characters, which are probably coupled with the same biological role and thus interlinked evolutionarily: (i) antennular peduncle and petasma (copulation); (ii) eyes and anterior thoracopods (feeding); and (iii) shape of carapace and pleon (defence). We analysed the evolutionary pathways of the clades into main oceanic biotopes and compared them with morphological adaptations most likely to be coupled with this process.     

Latitudinal‐diversity gradients can be shaped by biotic processes: new insights from an eco‐evolutionary model

The processes involved in shaping latitudinal‐diversity gradients (LDGs) have been a longstanding source of debate and research. Climatic, historical and evolutionary factors have all been shown to contribute to the formation of LDGs. However, meta‐analyses have shown that different clades have LDG slopes that may vary in more than one order of magnitude. Such large variation cannot be explained solely by climatic or historical factors (e.g. difference in surface area between temperate and tropical zones) given that all clades within a geographic region are subject to the same conditions. Therefore, biotic processes intrinsic to each taxonomic group could be relevant in explaining rate differences in diversity decline across latitudinal gradients among groups. In this study, we developed a model simulating multiple competing species subjected (or not) to a demographic Allee effect. We simulated the range expansion of these species across an environmental gradient to show how these two overlooked factors (competition and Allee effects) are capable of modulating LDGs. Allee effects resulted in a steeper LDG given a higher probability of local extinction and lower colonization capacity compared to species without Allee effects. Likewise, stronger competition also led to a steeper decline in species diversity compared to scenarios with weaker species antagonistic interactions. This pattern occurred mostly due to the strength of priority effects, wherein scenarios with strong competition, species that dispersed earlier in the landscape were able to secure many patches whereas late‐arriving species were progressively precluded from expanding their ranges. Overall, our results suggest that the effect of biotic processes in shaping macroecological patterns could be more important than it is currently appreciated.     

Exploring protein-protein interactions using the site-identification by ligand competitive saturation methodology

Protein docking methods are powerful computational tools to study protein-protein interactions (PPI). While a significant number of docking algorithms have been developed, they are usually based on rigid protein models or with limited considerations of protein flexibility and the desolvation effect is rarely considered in docking energy functions, which may lower the accuracy of the predictions. To address these issues, we introduce a PPI energy function based on the site-identification by ligand competitive saturation (SILCS) framework and utilize the fast Fourier transform (FFT) correlation approach. The free energy content of the SILCS FragMaps represent an alternative to traditional energy grids and they can be efficiently utilized to guide FFT-based protein docking. Application of the approach to eight diverse test cases, including seven from Protein Docking Benchmark 5.0, showed the PPI prediction using SILCS approach (SILCS-PPI) to be competitive with several commonly used protein docking methods indicating that the method has the ability to both qualitatively and quantitatively inform the prediction of PPI. Results show the utility of the SILCS-PPI docking approach for determination of probability distributions of PPI interactions over the surface of both partner proteins, allowing for identification of alternate binding poses. Such binding poses are confirmed by experimental crystal contacts in our test cases. While more computationally demanding than available PPI docking technologies, we anticipate that the SILCS-PPI docking approach will offer an alternative methodology for improved evaluation of PPIs that could be used in a variety of fields from systems biology to excipient design for biologics-based drugs.     

Calorimetric study of the order-disorder conformational transition in succinoglycan

Thermally induced order-disorder conformational transition in succinoglycan was studied using the method of high-sensitivity differential scanning microcalorimetry within the range of polysaccharide concentrations from 0.1 to 3.5 mg mL⁻¹ at NaCl concentrations 0, 0.01, and 0.1M. The positions and shapes of the excess heat capacity curves depended substantially on both the NaCl and polysaccharide concentrations. At low polysaccharide concentrations in salt-free solution the experimental curves were closely approximated by the two-state model suggesting the transition mechanism to be of the single helix-coil type. With increasing polysaccharide and/or NaCl concentration, the experimental curves changed significantly in symmetry, which indicated a changing transition mechanism. At high polysaccharide concentrations or in the presence of the salt, the order-disorder transition of succinoglycan was shown to include two stages: the cooperative dissociation of the helix dimer and subsequent two-state melting of the helix monomer. The dependence of thermodynamic parameters for the dissociation and melting of helix structures in succinoglycan on NaCl and polysaccharide concentrations was obtained by fitting the experimental excess heat capacity curves. The cooperativity parameter σ for the single helix-coil transition as well as the average length of the helix segment of succinoglycan were calculated. Some features of succinoglycan ordering in solution are discussed. © 1996 John Wiley & Sons, Inc.     

Maturity and fertility of rhesus monkey oocytes collected at different intervals after an ovulatory stimulus (human chorionic gonadotropin) in in vitro fertilization cycles

In rhesus monkeys undergoing ovarian stimulation for in vitro fertilization (IVF), a midcycle injection of human chorionic gonadotropin (hCG) substitutes for the LH surge and induces preovulatory oocyte maturation. The time interval between injection and oocyte collection, ideally, allows for the completion of oocyte maturation without ovulation, which would reduce the number of oocytes available for harvest. To evaluate the influence of this time interval on oocyte parameters following hCG administration, we conducted a series of gonadotropin treatment protocols in 51 animals in which the interval from hCG administration to follicular aspiration was systematically varied from 27 to 36 hr. Follicle number and size, evaluated prior to hCG administration by sonography, did not vary significantly or consistently with preovulatory maturation time. Oocytes were harvested by laparotomy or laparoscopy, and scored for maturity before insemination. The percentage of mature, metaphase II (MII) oocytes at recovery increased significantly with increasing preovulatory time and was inversely proportional to that of metaphase I (MI) oocytes. However, oocyte yield tended toward a progressive decrease with increasing preovulatory maturation times from a high of 27 oocytes at 27 hr to a low of 17 oocytes/animal at the 36 hr time interval. Fertilization levels declined significantly from a high of 50% at 27 hr to a low of 30% at 36 hr. Thus, although higher percentages of mature oocytes were recovered at the longer time intervals, optimal oocyte/embryo harvests were realized after the shorter time intervals (27 and 32 hr) and are most compatible with the goal of achieving high yields of fertile oocytes and embryos following gonadotropin stimulation in rhesus monkeys. © 1996 Wiley-Liss, Inc.