Advanced phenology of intraguild predators shifts herbivore host plant preference and performance

1. The abundance of insect herbivores is mediated by interactions with higher and lower trophic levels. This research asks (i) how phenological change across trophic levels affects host plant quality and selection for aphids, and (ii) what higher trophic level mechanisms drive aphid abundance. 2. Ligusticum porteri is a perennial host for the sap-feeding aphid Aphis asclepiadis and intraguild mirid predators (chiefly Lygus hesperus) in Colorado. We used long-term observational data to discover that aphids and mirids respond differently to phenological cues. These unique responses can impact aphid abundance through changes to host plant selection and quality. 3. We used behavioural choice assays to assess how advanced mirid phenology influences aphid host plant selection. More alates landed and reproduced on mirid-free control plants relative to host plants with prior mirid feeding. However, this preference did not correlate with aphid performance when we compared aphid relative growth rates between treatments. This suggests that advanced mirid phenology would impact aphid populations more through host plant choice, rather than reductions in host quality. The addition of mirids to experimental aphid colonies also demonstrated reduced aphid colony growth via predation. 4. We measured plant cues involved in host selection and found differences in volatile composition between plants with prior mirid feeding compared to control plants, providing the potential for aphids to detect enemy-free space using volatile cues.     

Intensity-Corrected Dual-Echo Echo-Planar Imaging (DE-EPI) for Improved Pediatric Brain Diffusion Imaging

Here we investigate the utility of a dual-echo Echo-Planar Imaging (DE-EPI) Diffusion Weighted Imaging (DWI) approach to improve lesion conspicuity in pediatric imaging. This method delivers two ‘echo images’ for one diffusion-preparation period. We also demonstrate how the echoes can be utilized to remove transmit/receive coil-induced and static magnetic field intensity modulations on both echo images, which often mimic pathology and thereby pose diagnostic challenges. DE-EPI DWI data were acquired in 18 pediatric patients with abnormal diffusion lesions, and 46 pediatric patient controls at 3T. Echo1 [TE = 45ms] and Echo2 [TE = 86ms] were corrected for signal intensity variation across the images by exploiting the images equivalent coil-sensitivity and susceptibility-induced modulations. Two neuroradiologists independently reviewed Echo1 and Echo2 and their intensity-corrected variants (cEcho1 and cEcho2) on a 7-point Likert scale, with grading on lesion conspicuity diagnostic confidence. The apparent diffusion coefficient (ADC) map from Echo1 was used to validate presence of true pathology. Echo2 was unanimously favored over Echo1 for its sensitivity for detecting acute brain injury, with a mean respective lesion conspicuity of 5.7/4.4 (p < 0.005) and diagnostic confidence of 5.1/4.3 (p = 0.025). cEcho2 was rated higher than cEcho1, with a mean respective lesion conspicuity of 5.5/4.3 (p < 0.005) and diagnostic confidence of 5.4/4.4 (p < 0.005). cEcho2 was favored over all echoes for its diagnostic reliability, particularly in regions close to the head coil. This work concludes that DE-EPI DWI is a useful alternative to conventional single-echo EPI DWI, whereby Echo2 and cEcho2 allows for improved lesion detection and overall higher diagnostic confidence.     

Behavioural modification of a social spider by a parasitoid wasp

1. Manipulation of host behaviour by parasitoids has long captured the imagination of ecologists. Parasitoid wasps in the Polysphincta group of genera develop as external parasitoids of spiders. 2. In the present study, the previously undescribed interaction between a Zatypota sp. wasp (Ichneumonidae) and a social spider Anelosimus eximius (Theridiidae) is described. The larva of this Zatypota wasp is found to induce its host to disperse from their communal web and build an entirely enclosed web consisting of densely spun silk. 3. The wasp is observed to target primarily immature A. eximius individuals, with 37.5–44% of nests in a given area being parasitised. Of those nests, approximately 1.3–2.0% of individuals are hosts to the parasitoid larvae. Larger spider colonies had a significantly higher probability of harbouring parasitoids. 4. This interaction results in unusual behaviours for A. eximius induced by the parasitoid: (i) leaving the protection of the social nest and (ii) building a unique, altered web that it would not otherwise build. It is suggested that the wasp may be tapping into ancestral dispersal behaviours in its host and that a social species provides this wasp an evolutionary advantage by allowing a stable host source.     

Osteopathology in Rhinocerotidae from 50 Million Years to the Present

Individual elements of many extinct and extant North American rhinocerotids display osteopathologies, particularly exostoses, abnormal textures, and joint margin porosity, that are commonly associated with localized bone trauma. When we evaluated six extinct rhinocerotid species spanning 50 million years (Ma), we found the incidence of osteopathology increases from 28% of all elements of Eocene Hyrachyus eximius to 65–80% of all elements in more derived species. The only extant species in this study, Diceros bicornis, displayed less osteopathologies (50%) than the more derived extinct taxa. To get a finer-grained picture, we scored each fossil for seven pathological indicators on a scale of 1–4. We estimated the average mass of each taxon using M1-3 length and compared mass to average pathological score for each category. We found that with increasing mass, osteopathology also significantly increases. We then ran a phylogenetically-controlled regression analysis using a time-calibrated phylogeny of our study taxa. Mass estimates were found to significantly covary with abnormal foramen shape and abnormal bone textures. This pattern in osteopathological expression may reflect a part of the complex system of adaptations in the Rhinocerotidae over millions of years, where increased mass, cursoriality, and/or increased life span are selected for, to the detriment of long-term bone health. This work has important implications for the future health of hoofed animals and humans alike.     

Endoplasmic reticulum stress causes insulin resistance by inhibiting delivery of newly synthesized insulin receptors to the cell surface

Accumulation of unfolded proteins in the endoplasmic reticulum (ER) causes ER stress and activates a signaling network known as the unfolded protein response (UPR). Here we characterize how ER stress and the UPR inhibit insulin signaling. We find that ER stress inhibits insulin signaling by depleting the cell surface population of the insulin receptor. ER stress inhibits proteolytic maturation of insulin proreceptors by interfering with transport of newly synthesized insulin proreceptors from the ER to the plasma membrane. Activation of AKT, a major target of the insulin signaling pathway, by a cytosolic, membrane-bound chimera between the AP20187-inducible F_V2E dimerization domain and the cytosolic protein tyrosine kinase domain of the insulin receptor was not affected by ER stress. Hence, signaling events in the UPR, such as activation of the JNK mitogen-activated protein (MAP) kinases or the pseudokinase TRB3 by the ER stress sensors IRE1α and PERK, do not contribute to inhibition of signal transduction in the insulin signaling pathway. Indeed, pharmacologic inhibition and genetic ablation of JNKs, as well as silencing of expression of TRB3, did not restore insulin sensitivity or rescue processing of newly synthesized insulin receptors in ER-stressed cells.     

CARBONIC ANHYDRASE IN THE MARINE DIATOM THALASSIOSIRA WEISSFLOGII (BACILLARIOPHYCEAE)1

The zinc metalloenzyme carbonic anhydrase plays a critical role in inorganic carbon acquisition in marine diatoms, thus conferring on zinc a key role in oceanic carbon cycling. As a first step in determining the location and function of carbonic anhydrase (CA) in Bacillariophyceae, we purified and partially sequenced CA from T. weissflogii (Gru) Fryxell et Hasle (TWCA1) and cloned the corresponding cDNA (twca1). The twca1 sequence is different from other known algal carbonic anhydrase genes, and encodes a protein of roughly 34 kDa. The amino terminal amino acids sequenced from purified TWCA1 are 72 residues downstream of the putative starting methionine predicted by twca1. This difference may be due to the presence of a short-lived signal sequence designed to guide the enzyme to the correct cellular location. The absence of any homology between TWCA1 and previously sequenced CAs from Chlorophyceae may indicate either convergent evolution or that carbon acquisition represents a fundamental physiological difference among algal phyla.     

Beyond pain in fibromyalgia: insights into the symptom of fatigue

Fatigue is a disabling, multifaceted symptom that is highly prevalent and stubbornly persistent. Although fatigue is a frequent complaint among patients with fibromyalgia, it has not received the same attention as pain. Reasons for this include lack of standardized nomenclature to communicate about fatigue, lack of evidence-based guidelines for fatigue assessment, and a deficiency in effective treatment strategies. Fatigue does not occur in isolation; rather, it is present concurrently in varying severity with other fibromyalgia symptoms such as chronic widespread pain, unrefreshing sleep, anxiety, depression, cognitive difficulties, and so on. Survey-based and preliminary mechanistic studies indicate that multiple symptoms feed into fatigue and it may be associated with a variety of physiological mechanisms. Therefore, fatigue assessment in clinical and research settings must consider this multi-dimensionality. While no clinical trial to date has specifically targeted fatigue, randomized controlled trials, systematic reviews, and meta-analyses indicate that treatment modalities studied in the context of other fibromyalgia symptoms could also improve fatigue. The Outcome Measures in Rheumatology (OMERACT) Fibromyalgia Working Group and the Patient Reported Outcomes Measurement Information System (PROMIS) have been instrumental in propelling the study of fatigue in fibromyalgia to the forefront. The ongoing efforts by PROMIS to develop a brief fibromyalgia-specific fatigue measure for use in clinical and research settings will help define fatigue, allow for better assessment, and advance our understanding of fatigue.     

Effects of carrion decomposition on litter arthropod assemblages

1. Many organisms contribute to the decomposition of carrion. For arthropods, many studies focus on the necrophagous community, those directly consuming carrion.
2. Necrophagous arthropods use carrion as a shelter or food source. Therefore, carrion generally increases the abundance and biodiversity of necrophagous species. However, it is unclear if carrion has similar effects on detrital communities.
3. This study examines changes in community structure and composition of necrophilous and detrital communities over the course of decomposition.
4. Five pig head carrion were placed at least 7 m apart under cages in temperate mixed forest. Leaf litter was sampled 0 m, 1.5 m, and 3 m from each carrion weekly during summer, and monthly during autumn, until the first frost. Arthropods were extracted from leaf litter by using Berlese funnels.
5. At the carrion site, necrophagous insects increased in abundance, species richness, and Shannon diversity during decomposition, and all decreased after dry decay.
6. Detritus arthropods displayed a sharp increase in abundance during advanced decay, decreasing during dry decay, and a general increase over time for species richness and diversity.
7. In conclusion, carrion can influence the surrounding, non-necrophagous arthropod community, highlighting the need to investigate carrion effects beyond typical necrophagous species to have a more holistic understanding of carrion ecology.