Structural changes in plastids of developing Splachnum ampullaceum sporophytes and relationship to odour production

Many mosses of the family Splachnaceae are entomophilous and rely on flies for spore dispersal. Splachnum ampullaceum produces a yellow- or pink-coloured hypophysis that releases volatile compounds, attracting flies to the mature moss. The biosynthetic sources of the visual and aromatic cues within the hypophysis have not been identified, and may be either symbiotic cyanobacteria or chromoplasts that break down lipids into volatile compounds. Here, we used transmission electron microscopy and gas chromatography-mass spectrometry (GC-MS) to investigate the sources of these attractants, focusing on different tissues and stages of maturation. Microscopy revealed an abundance of plastids within the hypophysis, while no symbiotic bacteria were observed. During plant maturation, plastids differentiated from amyloplasts with large starch granules to photosynthetic chloroplasts and finally to chromoplasts with lipid accumulations. We used GC-MS to identify over 50 volatile organic compounds from mature sporophytes including short-chain oxygenated compounds, unsaturated irregular terpenoids, fatty acid-derived 6- and 8-carbon alcohols and ketones, and the aromatic compounds acetophenone and p-cresol. The hypophysis showed localised production of pungent volatiles, mainly short-chain fermentation compounds and p-cresol. Some of these volatiles have been shown to be produced from lipid oxidase degradation of linolenic acid within chromoplasts. However, other compounds (such as cyclohexanecarboxylic acid esters) may have a microbial origin. Further investigation is necessary to identify the origin of fly attractants in these mosses

A 10-year experience in preoperative ultrasound imaging for parotid glands’ benign neoformations

Salivary gland neoplasms represent less than 4% of all head and neck lesions, being 80% in the parotid gland and usually benign. Imaging plays a key role in the evaluation of parotid gland masses. Ultrasound is cheap, with an excellent resolution and a safe real time assessment making it an ideal first evaluation option. Conversely, MRI is considered a second-line pre-surgery exam used to determine the location, the extension and the signal features of a parotid lesion. Both US and MRI are poorly reliable for predicting histology, therefore a fine-needle aspiration cytology (FNAC) is usually needed. In our retrospective study, we examined 263 patients with parotid diseases and a FNAC positive for a benign neoplasm, who underwent surgery between 2010 and 2020, in the departments of Otorhinolaryngology and Maxillofacial surgery in Verona. We compared a group of 126 patients preoperatively evaluated with ultrasound and a control group of 137 patients studied through third level imaging (usually MRI). In our case series, both third level imaging and US were used in equal measure, despite the lesion size. We found the recurrence rate to be almost the same between the two diagnostic methods and we saw that the patients studied through third level preoperative imaging had a higher complication rate and a worse facial nerve outcome. In our opinion, for patients with a FNAC positive for benign lesion the exclusive use of ultrasound imaging provides enough information to study the neoplasm while allowing for a faster and cheaper preoperative evaluation

Optical Coherence Tomography Angiography to estimate early retinal blood flow changes after uncomplicated cataract surgery

Background: To investigate macular microvascular changes after uncomplicated phacoemulsification surgery according to the cataract severity grade. Methods: Retrospective, cross-sectional study involving 23 eyes of 23 patients who underwent elective cataract extraction. All patients underwent routine ophthalmologic examination, including optical coherence tomography angiography (OCTA) at baseline (preoperative visit, T0) and seven days postoperatively (T7). OCTA scans were obtained with the spectral domain system Cirrus 5000 (Carl Zeiss Meditec, Inc., Dublin, CA, USA), and 3 mm × 3 mm raster fovea-centered scans were obtained to evaluate the superficial capillary plexus (SCP) vessel density, perfusion density, and foveal avascular zone (FAZ) parameters. Results: SCP perfusion density significantly increased from 28.3 ± 5.73% to 33.74 ± 4.13% after the surgery (p < 0.001). Similarly, SCP vessel density significantly increased from 15.14 ± 3.41 mm-1 to 18.14 ± 2.57 mm-1 after surgery (p < 0.001). The mean preoperative FAZ area significantly increased from 0.27 ± 0.12 mm to 0.24 ± 0.11 mm seven days postoperatively (p = 0.008). When comparing softer and harder cataracts, no significant variations in SCP vessel density, as well as SCP perfusion density parameters and the FAZ area, perimeter, and circularity index, were noted before and after surgery. Conclusions: Macular SPC vessel density and macular SCP perfusion density increase after uncomplicated cataract surgery regardless of the cataract severity

Intraspecific Combinations of Flower and Leaf Volatiles Act Together in Attracting Hawkmoth Pollinators

Insects pinpoint mates, food and oviposition sites by olfactory cues. Recognizing and localizing a suitable target by olfaction is demanding. Odor sources emit characteristic blends of compounds that have to be identified against an environmentally derived olfactory background. This background, however, does not necessarily disturb the localization of a source. Rather, the contrary. Sex pheromones become more attractive to male moths when being presented against a relevant plant background. Here we asked whether such olfactory coaction also characterizes foraging cues. The tobacco hornworm Manduca sexta feeds on nectar from wild tobacco Nicotiana attenuata and sacred datura Datura wrightii flowers. We tested how leaf-derived volatile blends as a background affect the moths' approach to flower blends. We found coaction when a flower blend was presented against a conspecific leaf volatile background but not when the blend was presented against volatiles emitted by the other host plant or by a non-host plant. Hence, our results reveal a species-specific coaction between flower blend and leaf volatile background. The ability to integrate information from different odor sources on one plant might provide the moth with a fine-grained analysis of food site quality

Herbivory by a Phloem-Feeding Insect Inhibits Floral Volatile Production

There is extensive knowledge on the effects of insect herbivory on volatile emission from vegetative tissue, but little is known about its impact on floral volatiles. We show that herbivory by phloem-feeding aphids inhibits floral volatile emission in white mustard Sinapis alba measured by gas chromatographic analysis of headspace volatiles. The effect of the Brassica specialist aphid Lipaphis erysimi was stronger than the generalist aphid Myzus persicae and feeding by chewing larvae of the moth Plutella xylostella caused no reduction in floral volatile emission. Field observations showed no effect of L. erysimi-mediated floral volatile emission on the total number of flower visits by pollinators. Olfactory bioassays suggested that although two aphid natural enemies could detect aphid inhibition of floral volatiles, their olfactory orientation to infested plants was not disrupted. This is the first demonstration that phloem-feeding herbivory can affect floral volatile emission, and that the outcome of interaction between herbivory and floral chemistry may differ depending on the herbivore's feeding mode and degree of specialisation. The findings provide new insights into interactions between insect herbivores and plant chemistry

Retention of Memory through Metamorphosis: Can a Moth Remember What It Learned As a Caterpillar?

Insects that undergo complete metamorphosis experience enormous changes in both morphology and lifestyle. The current study examines whether larval experience can persist through pupation into adulthood in Lepidoptera, and assesses two possible mechanisms that could underlie such behavior: exposure of emerging adults to chemicals from the larval environment, or associative learning transferred to adulthood via maintenance of intact synaptic connections. Fifth instar Manduca sexta caterpillars received an electrical shock associatively paired with a specific odor in order to create a conditioned odor aversion, and were assayed for learning in a Y choice apparatus as larvae and again as adult moths. We show that larvae learned to avoid the training odor, and that this aversion was still present in the adults. The adult aversion did not result from carryover of chemicals from the larval environment, as neither applying odorants to naïve pupae nor washing the pupae of trained caterpillars resulted in a change in behavior. In addition, we report that larvae trained at third instar still showed odor aversion after two molts, as fifth instars, but did not avoid the odor as adults, consistent with the idea that post-metamorphic recall involves regions of the brain that are not produced until later in larval development. The present study, the first to demonstrate conclusively that associative memory survives metamorphosis in Lepidoptera, provokes intriguing new questions about the organization and persistence of the central nervous system during metamorphosis. Our results have both ecological and evolutionary implications, as retention of memory through metamorphosis could influence host choice by polyphagous insects, shape habitat selection, and lead to eventual sympatric speciation

Discrimination Training with Multimodal Stimuli Changes Activity in the Mushroom Body of the Hawkmoth Manduca sexta

The mushroom bodies of the insect brain play an important role in olfactory processing, associative learning and memory. The mushroom bodies show odor-specific spatial patterns of activity and are also influenced by visual stimuli.Functional imaging was used to investigate changes in the in vivo responses of the mushroom body of the hawkmoth Manduca sexta during multimodal discrimination training. A visual and an odour stimulus were presented either together or individually. Initially, mushroom body activation patterns were identical to the odour stimulus and the multimodal stimulus. After training, however, the mushroom body response to the rewarded multimodal stimulus was significantly lower than the response to the unrewarded unimodal odour stimulus, indicating that the coding of the stimuli had changed as a result of training. The opposite pattern was seen when only the unimodal odour stimulus was rewarded. In this case, the mushroom body was more strongly activated by the multimodal stimuli after training. When no stimuli were rewarded, the mushroom body activity decreased for both the multimodal and unimodal odour stimuli. There was no measurable response to the unimodal visual stimulus in any of the experiments. These results can be explained using a connectionist model where the mushroom body is assumed to be excited by olfactory stimulus components, and suppressed by multimodal configurations.Discrimination training with multimodal stimuli consisting of visual and odour cues leads to stimulus specific changes in the in vivo responses of the mushroom body of the hawkmoth

Floral advertisement scent in a changing plant-pollinators market

Plant-pollinator systems may be considered as biological markets in which pollinators choose between different flowers that advertise their nectar/pollen rewards. Although expected to play a major role in structuring plant-pollinator interactions, community-wide patterns of flower scent signals remain largely unexplored. Here we show for the first time that scent advertisement is higher in plant species that bloom early in the flowering period when pollinators are scarce relative to flowers than in species blooming later in the season when there is a surplus of pollinators relative to flowers. We also show that less abundant flowering species that may compete with dominant species for pollinator visitation early in the flowering period emit much higher proportions of the generalist attractant β-ocimene. Overall, we provide a first community-wide description of the key role of seasonal dynamics of plant-specific flower scent emissions, and reveal the coexistence of contrasting plant signaling strategies in a plant-pollinator market

Relative Role of Flower Color and Scent on Pollinator Attraction: Experimental Tests using F1 and F2 Hybrids of Daylily and Nightlily

The daylily (Hemerocallis fulva) and nightlily (H. citrina) are typical examples of a butterfly-pollination system and a hawkmoth-pollination system, respectively. H. fulva has diurnal, reddish or orange-colored flowers and is mainly pollinated by diurnal swallowtail butterflies. H. citrina has nocturnal, yellowish flowers with a sweet fragrance and is pollinated by nocturnal hawkmoths. We evaluated the relative roles of flower color and scent on the evolutionary shift from a diurnally flowering ancestor to H. citrina. We conducted a series of experiments that mimic situations in which mutants differing in either flower color, floral scent or both appeared in a diurnally flowering population. An experimental array of 6×6 potted plants, mixed with 24 plants of H. fulva and 12 plants of either F1 or F2 hybrids, were placed in the field, and visitations of swallowtail butterflies and nocturnal hawkmoths were recorded with camcorders. Swallowtail butterflies preferentially visited reddish or orange-colored flowers and hawkmoths preferentially visited yellowish flowers. Neither swallowtail butterflies nor nocturnal hawkmoths showed significant preferences for overall scent emission. Our results suggest that mutations in flower color would be more relevant to the adaptive shift from a diurnally flowering ancestor to H. citrina than that in floral scent