Although studies on snow algae and macroinvertebrates have been frequently conducted on snow patches, only few surveys have been focused on microinvertebrates which reach high biomass and play ...various trophic roles in other cold habitats. The aims of this study were (1) to search for microinvertebrates in seasonal surface snow patches located on the slope of Mt. Gassan, in northern Japan, and (2) to identify factors determining their distribution associated with snow algal blooms of various colorations (orange, green, and golden-brown) collected from the same sampling site over two seasons (2018, 2019). Microscopic observation revealed presence of two major groups of microinvertebrates: Tardigrada and Rotifera. They were concentrated in green snow colored by blooms of Chloromonas sp. in comparison to orange or golden-brown snow and only a few were found in white snow. Mean body length of tardigrades increased throughout the melt season, their intestine content was green and they laid eggs on colored snow. These results suggest that tardigrades preferentially grew and reproduced on green snow patches. Population densities of tardigrades, rotifers and concentration of chlorophyll a were significantly correlated. Our study indicates that green snow patches in temperate mountainous forests constitute important and unique low-temperature ecosystems for microinvertebrates. Snow covered by algae is an unrecognized novel habitats for tardigrades and rotifers.
Bombus cryptarum florilegus
is a rare bumblebee in Japan. We tried to rear this bumblebee under laboratory conditions to investigate its nesting habits and colony development. Five queens out of 15 ...were successful in establishing colonies, and new queens and males were produced from these colonies. In the laboratory colonies, the average numbers of workers, males, and new queens per colony of
B. cryptarum florilegus
were 15.2 ± 4.7, 26.0 ± 8.0, and 2.0 ± 2.1, respectively. Although a feral colony producing five hundred cocoons has been reported,
B. cryptarum florilegus
established small colonies under laboratory conditions. Further study suggests that the improvement of rearing technique is required to produce the large colony of
B. cryptarum florilegus
.
Snow ecosystems are an important component of polar and mountainous regions, influencing water regime, biogeochemical cycles and supporting snow specific taxa. Although snow is considered to be one ...of the most unique, and at the same time a disappearing habitat, knowledge of its taxonomic diversity is still limited. It is true especially for micrometazoans appearing in snow algae blooming areas. In this study, we used morphological and molecular approaches to identify two tardigrade species found in green snow patches of Mt. Gassan in Japan. By morphology, light (PCM) and scanning electron microscopy (SEM), and morphometry we described Hypsibius nivalis sp. nov. which differs from other similar species by granular, polygonal sculpture on the dorsal cuticle and by the presence of cuticular bars next to the internal claws. Additionally, phylogenetic multilocus (COI, 18S rRNA, 28S rRNA) analysis of the second taxon, Hypsibius sp. identified by morphology as convergens-pallidus group, showed its affinity to the Hypsibiidae family and it is placed as a sister clade to all species in the Hypsibiinae subfamily. Our study shows that microinvertebrates associated with snow are poorly known and the assumption that snow might be inhabited by snow-requiring tardigrade taxa cannot be ruled out. Furthermore, our study contributes to the understanding subfamily Hypsibiinae showing that on its own the morphology of specimens belonging to convergens-pallidus group is insufficient in establishing a true systematic position of specimens.
Abstract
Some aphid species produce a soldier caste with enlarged forelegs and horns (weapons). It has been hypothesised that the evolution of morphological specialization by soldiers in social ...aphids is accelerated by high predation pressure, but this possibility has not been tested. Here, we investigated the relationship between local predator abundance and soldiers’ weapon size and aggressiveness in a prey–predator system comprising a eusocial aphid,
Ceratovacuna japonica
, and its predators (larvae of the butterfly
Taraka hamada
and of the moth
Atkinsonia ignipicta
) in two populations with different predator abundances. We found that the soldiers in the predator-abundant population had larger weapons and were more aggressive than those in the population with lower predator abundance. Furthermore, the soldiers’ defensive prowess (evaluated as the survival of aphids in the presence of predators) was greater in the predator-abundant population. These results provide the first evidence that a population of eusocial aphids experiencing high predation pressure has soldiers with pronounced defensive traits and defensive prowess.
•Freeze-thaw cycles required to kill tardigrades are associated with characteristics of their habitats.•The number of cycles required to kill tardigrades was the highest for mountainous ...species.•Tardigrades from lowlands were the most sensitive to changes.•Tardigrades are models of how FTC impact ubiquitous microscopic invertebrates.•Mortality of tardigrades could be indicator of the disappearance of invertebrate specialists.
Global warming effects in temperate and polar regions include higher average temperatures and a decrease in snow cover, which together lead to an increase in the number of freeze–thaw cycles (FTC). These changes could affect the fitness of both terrestrial and aquatic species. In this study, we tested how tardigrades, ubiquitous microscopic invertebrates, face FTC. Tardigrades are amongst the most resistant animals to unfavorable conditions, including long and deep freezing periods, and are an emerging model group for invertebrate ecology and evolution. We used 12 populations of tardigrades, representing different families within order Parachela, inhabiting different ecosystems (glaciers, snow, terrestrial, aquatic), found in various substrates (mosses, sediments in lakes, cryoconite on glaciers, and snow), and originating from different latitudes and altitudes. We estimated the number of cycles required to kill 50% of individuals and tested for its association with ecological characteristics of the natural habitat (e.g., number of months with predicted FTC), while accounting for phylogeny. The most resistant tardigrades to FTC were the ones from mountain areas and glaciers. The estimated number of cycles required to kill 50% of individuals was the highest for mountainous species inhabiting rock pools and cryoconite holes on glaciers (30 and 14 FTC, respectively). Tardigrades from lowlands were the most sensitive to changes, with 50% of individuals dying after three FTC, while lacustrine and subtropical tardigrades required only one FTC to reach 50% mortality. Our study shows that the response to recurrent freezing stress is taxon dependent and related to the local environmental conditions. The predicted increase of FTC cycles will negatively impact tardigrade populations. Considering the abundance and various trophic roles of tardigrades, reduction in population sizes or the disappearance of some fragile species could affect the functioning of both aquatic and terrestrial ecosystems. Tardigrades are candidate indicators of how freeze–thaw cycles impact ubiquitous microscopic metazoans with similar physiological capabilities.
Honey bees and bumble bees belong to the same family (Apidae) and their workers exhibit a division of labor, but the style of division of labor differs between species. The molecular and neural bases ...of the species-specific social behaviors of Apidae workers have not been analyzed. Here, we focused on two immediate early genes, hormone receptor 38 (HR38) and early growth response gene-1 (Egr1), and late-upregulated ecdysone receptor (EcR), all of which are upregulated by foraging flight and expressed preferentially in the small-type Kenyon cells of the mushroom bodies (MBs) in the honey bee brain. Gene expression analyses in Bombus ignitus revealed that HR38 and Egr1, but not EcR, exhibited an immediate early response during awakening from CO
anesthesia. Both premature mRNA for HR38 and mature mRNA for Egr1 were induced during foraging flight, and mRNAs for HR38 and Egr1 were sparsely detected inside the whole MB calyces. In contrast, EcR expression was higher in forager brains than in nurse bees and was expressed preferentially in the small-type Kenyon cells inside the MBs. Our findings suggest that Kenyon cells are active during foraging flight and that the function of late-upregulated EcR in the brain is conserved among these Apidae species.
The efficacy of preoperative neoadjuvant chemoradiotherapy (NAC) in cases of pancreatic cancer with extremely poor prognoses has been reported. In this study, we aimed to identify novel biomarkers ...that reflect prognoses following chemoradiotherapy using tertiary lymphoid organs (TLO) expressed in the tumor microenvironment. Resected tumor specimens were obtained from 140 pancreatic cancer patients. We retrospectively investigated the clinical relevance of TLO by categorizing patients into those who underwent upfront surgery (surgery first SF) and those who received NAC. The immunological elements within TLO were analyzed by immunohistochemistry (IHC). In the IHC analysis, the proportions of CD8+ T lymphocytes, PNAd+ high endothelial venules, CD163+ macrophages and Ki‐67+ cells within the TLO were higher in the NAC group than in the SF group. In contrast, the proportion of programmed cell death‐1+ immunosuppressive lymphocytes within TLO was lower in the NAC group than in the SF group. The NAC group demonstrated favorable prognoses compared with the SF group. In the multivariate analysis, the TLO/tumor ratio was determined as an independent predictive prognostic factor. In conclusion, the administration of preoperative chemoradiotherapy may influence the immunological elements in the tumor microenvironment and result in favorable prognoses in pancreatic ductal adenocarcinoma patients.
The administration of preoperative chemoradiotherapy may influence the immunological elements in the tumor microenvironment and result in favorable prognoses in pancreatic ductal adenocarcinoma patients.
The rapid naturalization of Bombus terrestris across the Nemuro Peninsula has led to a decline in two closely related native Japanese species, namely Bombus hypocrita sapporensis and Bombus cryptarum ...florilegus, both belonging to the common subgenus Bombus. Although it is widely believed that cross-mating of native and non-native species is influenced by the common male sex pheromone in this region, no study has been conducted to substantiate this claim. Thus, we investigated the cross-activities of male sex pheromones between native and non-native bumblebees, as well as the frequencies of cross-mating, using chemical and DNA assays. Our gas chromatography-electroantennographic detector analyses and behavioral tests revealed the presence of sex pheromonal cross-activities between B. terrestris and the two Japanese bumblebees species. Furthermore, DNA analyses revealed the occurrence of cross-mating between native and non-native species in the Nemuro Peninsula. Overall, these results indicate the immediate need for conservation measures to safeguard Japanese bumblebee populations in the Nemuro Peninsula.
Display omitted
•Colony founding queens had depressed dopamine levels in the brains.•Brain dopamine levels were correlated with other ganglia and hemolymph in queens.•In virgin queens, dopamine ...levels were not correlated with ovarian activity.•In workers, dopamine levels were positively correlated with ovarian activity.•Dopamine may play a role in ovarian activity in workers, but not in queens.
A society of bumble bees is primitively eusocial, with an annual life cycle, and can be used as a physiological model of social bees for comparative studies with highly eusocial hymenopterans. We investigated the dynamics of biogenic amine levels in the brain, meso-metathoracic ganglia, terminal abdominal ganglion, and hemolymph in queens 1 day after mating (1DAM), during diapause (Dp), and during colony founding (CF) in the bumble bee, Bombus ignitus. Dopamine levels in the brain of CF queens were significantly lower than in 1DAM and Dp queens, and the levels in the thoracic ganglia and hemolymph in CF queens were lower than in 1DAM queens, but did not differ from other groups in the abdominal ganglion. Octopamine levels in the brains were higher in Dp queens than in 1DAM queens. Serotonin and tyramine levels did not differ between the groups in different compartments of the central nervous system (CNS) that we examined. The dopamine levels in the brains were significantly positively correlated with those in the thoracic ganglia, abdominal ganglion, and hemolymph, suggesting the regulation of dopamine levels among three different compartments of the CNS. In isolated virgin queens, there were no significant correlations between the brain levels of biogenic amines that we examined and the lengths of the largest terminal oocytes, whereas, in isolated workers, the brain dopamine levels were positively correlated with oocyte lengths. These results suggest that dopamine is associated with ovarian activity in reproductive workers, but not in either virgin or mated queens.
PDF
