Brain microvasculature has a common topology with local differences in geometry that match metabolic load

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Cell membrane punctures during epidermal penetrations by aphids: consequences for the transmission of two potyviruses

Electrical penetration graphs (EPGs) were used to investigate aphid stylet activities during brief penetrations and the importance of these events for the nonpersistent transmission of two potyviruses, beet mosaic virus (BMV) and potato virus Y (PVY). Stylet puncture of a cell membrane, recorded as a potential drop, was correlated with the acquisition and inoculation of PVY and acquisition of BMV by Myzus persicae.     

Arthropoda of the subantarctic islands of New Zealand

Ischyroplectron isolatum (Hutton) is redescribed from the Bounty Islands, south‐east of New Zealand. The relationships of the subantarctic Orthoptera are discussed. A key is given to the four genera of Rhaphidophoridae.     

Fullerene-like structures of Cretaceous crinoids reveal topologically limited skeletal possibilities

There are few cases where numbers or types of possible phenotypes are known, although vast state spaces have been postulated. Rarely applied in this context, graph theory and topology enable enumeration of possible phenotypes and evolutionary transitions. Here, we generate polyhedral calyx graphs for the Late Cretaceous, stemless crinoids Marsupites testudinarius and Uintacrinus socialis (Uintacrinoidea Zittel) revealing structural similarities to carbon fullerene and fulleroid molecules (respectively). The U. socialis calyx incorporates numerous plates (e.g. graph vertices |V| ≥ 197), which are small, light, low-density and have four to eight sides. Therefore, the corresponding number of possible plate arrangements (number of polyhedral graphs) is large (≫1 × 10¹⁴). Graph vertices representing plates with sides >6 introduce negative Gaussian curvature (surface saddle points) and topological instability, increasing buckling risk. However, observed numbers of vertices for Uintacrinus do not allow more stable pentaradial configurations. In contrast, the Marsupites calyx dual graph has 17 faces that are pentagonal or hexagonal. Therefore, it is structurally identical to a carbon fullerene, specifically C30-D5h. Corresponding graph restrictions result in constraint to only three structural options (fullerene structures C30-C2v 1, C30-C2v 2 and C30-D5h). Further restriction to pentaradial symmetry allows only one possibility: the Marsupites phenotype. This robust, stable topology is consistent with adaptation to predation pressures of the Mesozoic marine revolution. Consequently, the most plausible evolutionary pathway between unitacrinoid phenotypes was a mixed heterochronic trade-off to fewer, larger calyx plates. Therefore, topological limitations radically constrained uintacrinoid skeletal possibilities but thereby aided evolution of a novel adaptive phenotype.     

Electrical Penetration Graph analysis reveals population differentiation of host-plant probing behaviors within the aphid species Uroleucon ambrosiae

Uroleucon ambrosiae collected from the eastern and the southwestern United States were studied in relation to host-plant probing. In the field, eastern aphids are highly specific on Ambrosia trifida, while southwestern aphids feed on Ambrosia trifida plus many other species in the family Asteraceae. Electrical penetration graphs of insects on the principal host, A. trifida, and an additional host of southwestern populations, Heterotheca subaxillaris, revealed regional differentiation in host-associated aphid behaviors, specifically in the first phase of subcuticular probing, and in phloem finding activities. Eastern aphids used A. trifidamore efficiently than southwestern aphids, but were demonstrably less vigorous in their probing activities on H. subaxillaris.     

Reproduction and probing behaviour of the bird cherry‐oat aphid Rhopalosiphum padi on detached leaves and leaves on intact seedlings of the winter host,bird cherry Prunus padus

Video recording and electrical penetration graph techniques are used simultaneously to investigate host acceptance (in terms of reproduction) and probing activities of autumn migrants (gynoparae) of the bird cherry‐oat aphid Rhopalosiphum padi (L.) on detached leaves and on leaves on intact plants of the winter host, bird cherry Prunus padus. There are no significant differences between the times taken to first parturition or the number of nymphs produced over a 6‐ or 18‐h period on intact plants or detached leaves. Stylet probing activities (i.e. total probe duration, xylem ingestion, the time to first phloem contact and phloem salivation) are also similar in the two situations.     

Graph identification of proteins in tomograms (GRIP-Tomo)

In this study, we present a method of pattern mining based on network theory that enables the identification of protein structures or complexes from synthetic volume densities, without the knowledge of predefined templates or human biases for refinement. We hypothesized that the topological connectivity of protein structures is invariant, and they are distinctive for the purpose of protein identification from distorted data presented in volume densities. Three-dimensional densities of a protein or a complex from simulated tomographic volumes were transformed into mathematical graphs as observables. We systematically introduced data distortion or defects such as missing fullness of data, the tumbling effect, and the missing wedge effect into the simulated volumes, and varied the distance cutoffs in pixels to capture the varying connectivity between the density cluster centroids in the presence of defects. A similarity score between the graphs from the simulated volumes and the graphs transformed from the physical protein structures in point data was calculated by comparing their network theory order parameters including node degrees, betweenness centrality, and graph densities. By capturing the essential topological features defining the heterogeneous morphologies of a network, we were able to accurately identify proteins and homo-multimeric complexes from 10 topologically distinctive samples without realistic noise added. Our approach empowers future developments of tomogram processing by providing pattern mining with interpretability, to enable the classification of single-domain protein native topologies as well as distinct single-domain proteins from multimeric complexes within noisy volumes.