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Background: Climate change has recently boosted the severity and frequency of pine bark beetle attacks. The bacterial community associated with these beetles acts as "hidden players," enhancing their ability to infest and thrive on defense-rich pine trees. There is limited understanding of the environmental acquisition of these hidden players and their life stage-specific association with different pine-feeding bark beetles. There is inadequate knowledge on novel bacterial introduction to pine trees after the beetle infestation. Hence, we conducted the first comparative bacterial metabarcoding study revealing the bacterial communities in the pine trees before and after beetle feeding and in different life stages of two dominant pine-feeding bark beetles, namely Ips sexdentatus and Ips acuminatus . We also evaluated the bacterial association between wild and lab-bred beetles to measure the deviation due to inhabiting a controlled environment., Results: Significant differences in bacterial amplicon sequence variance (ASVs) abundance existed among different life stages within and between the pine beetles. However, Pseudomonas, Serratia, Pseudoxanthomonas, Taibaiella, and Acinetobacter served as core bacteria. Interestingly, I. sexdentatus larvae correspond to significantly higher bacterial diversity and community richness and evenness compared to other developmental stages, while I. acuminatus adults displayed higher bacterial richness with no significant variation in the diversity and evenness between the life stages. Both wild and lab-bred I. sexdentatus beetles showed a prevalence of the bacterial family Pseudomonadaceae. In addition, wild I. sexdentatus showed dominance of Yersiniaceae, whereas Erwiniaceae was abundant in lab-bred beetles. Alternatively, Acidobacteriaceae , Corynebacteriaceae , and Microbacteriaceae were highly abundant bacterial families in lab-bred, whereas Chitinophagaceae and Microbacteriaceae were highly abundant in wild I. accuminatus. We validated the relative abundances of selected bacterial taxa estimated by metagenomic sequencing with quantitative PCR., Conclusion: Our study sheds new insights into bacterial associations in pine beetles under the influence of various drivers such as environment, host, and life stages. We documented that lab-breeding considerably influences beetle bacterial community assembly. Furthermore, beetle feeding alters bacteriome at the microhabitat level. Nevertheless, our study revisited pine-feeding bark beetle symbiosis under the influence of different drivers and revealed intriguing insight into bacterial community assembly, facilitating future functional studies., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Khara, Chakraborty, Modlinger, Synek and Roy.)

Host shift is ecologically advantageous and a crucial driver for herbivore insect speciation. Insects on the non-native host obtain enemy-free space and confront reduced competition, but they must adapt to survive. Such signatures of adaptations can often be detected at the gene expression level. It is astonishing how bark beetles cope with distinct chemical environments while feeding on various conifers. Hence, we aim to disentangle the six-toothed bark beetle (Ips sexdentatus) response against two different conifer defences upon host shift (Scots pine to Norway spruce). We conducted bioassay and metabolomic analysis followed by RNA-seq experiments to comprehend the beetle's ability to surpass two different terpene-based conifer defence systems. Beetle growth rate and fecundity were increased when reared exclusively on spruce logs (alternative host) compared to pine logs (native host). Comparative gene expression analysis identified differentially expressed genes (DEGs) related to digestion, detoxification, transporter activity, growth, signalling, and stress response in the spruce-feeding beetle gut. Transporter genes were highly abundant during spruce feeding, suggesting they could play a role in pumping a wide variety of endogenous and xenobiotic compounds or allelochemicals out. Trehalose transporter (TRET) is also up-regulated in the spruce-fed beetle gut to maintain homeostasis and stress tolerance. RT-qPCR and enzymatic assays further corroborated some of our findings. Taken together, the transcriptional plasticity of key physiological genes plays a crucial role after the host shift and provides vital clues for the adaptive potential of bark beetles on different conifer hosts., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Eurasian spruce bark beetle, Ips typographus is a destructive pest of the Norway spruce ( Picea abies ). Recent outbreaks in Europe have been attributed to global warming and other anthropogenic impacts. Bark beetles are guided by multiple complex olfactory cues throughout their life cycle. Male-produced aggregation pheromones, comprising 2-methyl-3-buten-2-ol and cis -verbenol, have been identified as the most powerful attractants for dispersing conspecifics. In addition to host trees, bark beetles interact with multiple organisms, including symbiotic ophiostomatoid fungi, which may promote beetle colonization success and offspring development. Previously, in a short-distance laboratory assay, we demonstrated that I. typographus adults are attracted to the volatile organic compounds (VOCs) produced by three symbiotic fungi: Grosmannia penicillata , Endoconidiophora polonica , and Leptographium europhioides . Furthermore, the abundant fusel alcohols and their acetates were found to be the most attractive odorants in the fungal VOC profile. In this study, using a long-distance field-trapping experiment, we analyzed the role of fungal VOCs as attractants for dispersing I. typographus . Two types of fungal lures were tested in combination with pheromones in traps: (1) live cultures of fungi grown on potato dextrose agar (PDA) and (2) dispensers containing synthetic fusel alcohols and their acetates in equal proportions. Subsequently, the composition of VOCs emitted from live fungal lures were analyzed. We found that the symbiotic fungi synergistically increased the attraction of beetles to pheromones in field traps and the attractiveness of live fungal lures depended on the fungal load. While one Petri dish with E. polonica , when combined with pheromones synergistically increased trapping efficiency, three Petri dishes with L. europhioides were required to achieve the same. The synthetic mix of fungal fusel alcohols and acetates improved the catch efficiency of pheromones only at a low tested dose. VOC analysis of fungal cultures revealed that all the three fungi produced fusel alcohols and acetates but in variable composition and amounts. Collectively, the results of this study show that, in addition to pheromones, bark beetles might also use volatile cues from their symbiotic fungi to improve tree colonization and reproductive success in their breeding and feeding sites., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Jirošová, Modlinger, Hradecký, Ramakrishnan, Beránková and Kandasamy.)

Background: Eurasian spruce bark beetles (Ips typographus) use both attractant and anti-attractant semiochemicals to find suitable mature host trees. Trans-4-thujanol is abundant in young, unsuitable spruce trees. Electrophysiological studies have demonstrated its high activity levels, but field data are lacking., Results: Enantioselective GC-MS analysis showed that only (1R,4S)-(+)-trans-4-thujanol was present in Norway spruce bark volatiles. In a factorial design field-trapping experiment, trans-4-thujanol alone was not attractive to Ips typographus. Traps baited with I. typographus' aggregation pheromone and trans-4-thujanol or the known anti-attractant 1,8-cineole caught fewer beetles than those baited with the aggregation pheromone alone. Catches for trans-4-thujanol and 1,8-cineole were dose-dependent. Intermediate doses of trans-4-thujanol and 1,8-cineole had a similar effect. Surprisingly, in contrast to 1,8-cineole and other known Ips anti-attractants, which all inhibit males more strongly than females, the addition of trans-4-thujanol to the aggregation pheromone reduced the attraction of females more., Conclusion: The Norway spruce volatile (+)-trans-4-thujanol is a novel I. typographus anti-attractant with potency comparable to the known anti-attractants 1,8-cineole and verbenone, and is more effective for females than for males. Incorporating (+)-trans-4-thujanol into anti-attractant lures could improve protection of trees from mass attack by I. typographus., (© 2022 Society of Chemical Industry.)

Ips sexdentatus (Coleoptera: Curculionidae: Scolytinae) is one of the most destructive and economically important forest pests. A better understanding of molecular mechanisms underlying its adaptation to toxic host compounds may unleash the potential for future management of this pest. Gene expression studies could be considered as one of the key experimental approaches for such purposes. A suitable reference gene selection is fundamental for quantitative gene expression analysis and functional genomics studies in I. sexdentatus . Twelve commonly used reference genes in Coleopterans were screened under different experimental conditions to obtain accurate and reliable normalization of gene expression data. The majority of the 12 reference genes showed a relatively stable expression pattern among developmental stages, tissue-specific, and sex-specific stages; however, some variabilities were observed during varied temperature incubation. Under developmental conditions, the Tubulin beta-1 chain (β -Tubulin ) was the most stable reference gene, followed by translation elongation factor ( eEF2 ) and ribosomal protein S3 ( RPS3 ). In sex-specific conditions, RPS3 , β -Tubulin , and eEF2 were the most stable reference genes. In contrast, different sets of genes were shown higher stability in terms of expression under tissue-specific conditions, i.e., RPS3 and eEF2 in head tissue, V-ATPase-A and eEF2 in the fat body, V-ATPase-A and eEF2 in the gut. Under varied temperatures, β -Tubulin and V-ATPase-A were most stable, whereas ubiquitin (UbiQ) and V-ATPase-A displayed the highest expression stability after Juvenile Hormone III treatment. The findings were validated further using real-time quantitative reverse transcription PCR (RT-qPCR)-based target gene expression analysis. Nevertheless, the present study delivers a catalog of reference genes under varied experimental conditions for the coleopteran forest pest I. sexdentatus and paves the way for future gene expression and functional genomic studies on this species., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Sellamuthu, Amin, Bílý, Synek, Modlinger, Sen, Chakraborty and Roy.)

Bark beetles often serve as forest damaging agents, causing landscape-level mortality. Understanding the biology and ecology of beetles are important for both, gathering knowledge about important forest insects and forest protection. Knowledge about the bark beetle gut-associated bacteria is one of the crucial yet surprisingly neglected areas of research with European tree-killing bark beetles. Hence, in this study, we survey the gut bacteriome from five Ips and one non-Ips bark beetles from Scolytinae. Results reveal 69 core bacterial genera among five Ips beetles that may perform conserved functions within the bark beetle holobiont. The most abundant bacterial genera from different bark beetle gut include Erwinia, Sodalis, Serratia, Tyzzerella, Raoultella, Rahnella, Wolbachia, Spiroplasma, Vibrio, and Pseudoxanthomonas. Notable differences in gut-associated bacterial community richness and diversity among the beetle species are observed. Furthermore, the impact of sampling location on the overall bark beetle gut bacterial community assemblage is also documented, which warrants further investigations. Nevertheless, our data expanded the current knowledge about core gut bacterial communities in Ips bark beetles and their putative function such as cellulose degradation, nitrogen fixation, detoxification of defensive plant compounds, and inhibition of pathogens, which could serve as a basis for further metatranscriptomics and metaproteomics investigations.

Bark beetles are destructive forest pests considering their remarkable contribution to forest depletion. Their association with fungi is useful against the challenges of survival on the noxious and nutritionally limited substrate, i.e., conifer tissues. Fungal symbionts help the beetles in nutrient acquisition and detoxification of toxic tree secondary metabolites. Although gut is the prime location for food digestion and detoxification, limited information is available on gut-mycobiome of bark beetles. The present study screened the gut-mycobiont from six bark beetles (five Ips and one non- Ips ) from Scolytinae subfamily using high-throughput sequencing and explored their putative role in symbiosis with the host insect. Results revealed the predominance of four fungal classes- Sordariomycetes, Saccharomycetes, Eurothiomycetes, and Dothidomycetes in all bark beetles. Apart from these, Agaricomycetes, Leothiomycetes, Incertae sedis Basidiomycota, Tremellomycetes, Lecanoromycetes, and Microbotryomycetes were also documented in different beetles. Five Ips bark beetles share a consortium of core fungal communities in their gut tissues consisting of 47 operational taxonomic units (OTUs) belonging to 19 fungal genera. The majority of these core fungal genera belong to the phylum Ascomycota. LEfSe analysis revealed a set of species-specific fungal biomarkers in bark beetles. The present study identified the gut mycobiont assemblage in bark beetles and their putative ecological relevance. An enriched understanding of bark beetle-fungal symbiosis is not only filling the existing knowledge gap in the field but may also unleash an unforeseen potential for future bark beetle management., (Copyright © 2020 Chakraborty, Modlinger, Ashraf, Synek, Schlyter and Roy.)

Previous work from this laboratory indicated significant elevations of cortisol after the administration of tryptophan. The current investigation was designed to confirm this observation and study the effect of this agent on ACTH. Cortisol rose 12.4 +/- 5.2 microgram/dl (mean +/- SD) in 10 of 12 tests (P less than 0.02). Responding patients had rises of ACTH averaging 101.8 +/- 45.8% (range, 40-159 pg/ml) above baseline. The time course of the ACTH change closely paralleled that of cortisol, and there were significant correlations between the rises of the two substances (r = 0.81; P less than 0.01). The current data strongly suggest that tryptophan administration stimulates ACTH release, possibly through activation of the central serotonergic nervous system. Review of the literature suggests the possibility that ACTH stimulation only occurs at high plasma tryptophan (and presumably brain serotonin) concentrations, with ACTH inhibition occuring at lower levels.

Tryptophan administration was used to evaluate the possibility that serotonergic neurons are involved in regulating the release of cortisol, renin, and aldosterone. Eleven studies were undertaken using 2 or 10 g tryptophan administered to fasting patients in continued supine posture. Aldosterone rose significantly to 208% (range, 128-329%) of baseline in all seven studies using 10 g and in one of the four studies using 2 g. Renin rose significantly to 189% (range, 116-340%) of baseline in four of the seven studies using 10 g and in two of the four studies using 2 g. Cortisol rose from 10.1 +/- 3.3 to 20.0 +/- 3.7 micrograms/100 ml (P less than 0.001 by t test) in six of the seven studies using 10 g and three of the four studies using 2 g. In eight studies, there was a significant rise of more than one substance after tryptophan administration. In six of these, peak values of the responding hormones occurred at the same time or within a single 30-min sampling interval despite the absence of a constant relationship between their rises. The results suggest participation of the central serotonergic nervous system in the control of renin and aldosterone in addition to its previously postulated role in cortisol release.

In a 54-year-old man with a norepinephrine-secreting pheochromocytoma, resistance developed to the alpha-adrenergic blocking agent, phenoxybenzamine hydrochloride. Dosages of 240 mg/day were ineffective. Intravenous phentolamine mesylate reduced his BP at first, but resistance developed to this also. Therapy with alpha-methylparatyrosine, an inhibitor of catecholamine biosynthesis, finally controlled his BP, and the tumor was removed.

The circadian periodicity of plasma renin activity (PRA) during continuous recumbency was determined five times in a patient with primary hyperaldosteronism. All curves were parallel with one another. There were significant elevations of PRA at 1600-2000 h, falls at 2400 h, and peaks at 0200-0800 h. This periodicity was uninfluenced by changes in baseline PRA, serum potassium concentration, salt intake, plasma volume, blood pressure, or mineralocorticoid effect. It persisted despite inability of the patient to sleep on two nights. It is suggested that the observed periodicity of renin is a true endogenous diurnal rhythm of possible central nervous system origin.

Intravenous hydralazine, 0.15, 0.30 or 0.60 mg/kg, was administered to 11 supine hypertensives on two occasions: once after pretreatment with intravenous propranolol, 0.1 mg/kg, and once after pretreatment with intravenous placebo. The average fall in mean arterial pressure for each dosage of hydralazine was no different with or without propranolol, even though propranolol inhibited rises in plasma renin activity and pulse due to hydralazine. However, in each of four patients who had high supine baseline plasma renin activity, propranolol enhanced the fall in blood pressure caused by hydralazine. A second group of patients was given an infusion of 0.01 or 0.02 mg/kg per minute phentolamine, which did not change baseline blood pressure. Subsequent administration of intravenous hydralazine, 0.15 mg/kg, resulted in a fall in blood pressure which was larger than previously observed with intravenous hydralazine alone, regardless of supine baseline plasma renin activity. These data are consistent with the hypothesis that reflex catecholamine release interferes with the hypotensive effect of intravenous hydralazine. Pretreating with propranolol weakens homeostatic defenses against hydralazine such as rises in pulse rate and plasma renin activity. However, propranolol appears to enhance the alpha-adrenergic effect of released catecholamines, and the antihypertensive response to hydralazine is unaltered. In patients with high supine plasma renin activity, propranolol potentiates the fall in blood pressure induced by hydralazine, perhaps because the hypertension in such patients is renin dependent.

Plasma prolactin response to postural change and variation in dietary sodium was evaluated in five normal volunteers and 15 patients with essential hypertension. Values at 0800 hours (11.9 +/- 3.5 ng/ml, mean +/- 1 S.D.) were uninfluenced by the duration of recumbency (10 or 34 hr) and were significantly higher than those obtained at noon (6.9 +/- 3.5 ng/ml, mean +/- 1 S.D., p less than 0.001). The latter were uninfluenced by postural change. There was no correlation between sodium intake and plasma prolactin, nor was there any apparent correlation between prolactin and plasma renin activity. There was no significant difference in prolactin concentrations between normotensive and hypertensive subjects. In 10 additional patients with unilateral renal disease, renal vein prolactin concentrations did not differ significantly from simultaneously obtained peripheral concentrations. Renal vein prolactin was uninfluenced by the presence of renal disease and did not correlate with renal blood flow. It is concluded that there is no evidence of feedback between sodium intake and prolactin in man. Human kidneys do not seem to clear significant amounts of prolactin. It appears unlikely that alterations in prolactin concentration, at least as assessed by daytime values, participate in the maintenance of either essential or renovascular hypertension. Since values at 0800 hours are frequently elevated as a reflection of preceding sleep-related peaks, sampling at 1200 hours may be preferable when search is undertaken for hypothalamic-pituitary disease.

The circadian rhythm of plasma renin activity during continuous recumbency was determined fifty-one times in thirty subjects who either slept at night or remained awake for 24 h. Both groups had maximum values between 2400 and 0800 h, despite absence of the expected early morning fall in blood pressure, pulse, and glomerular filtration rate in the awake subjects. Infusion of normal saline between 2300 and 0300 h initially suppressed renin, but did not prevent its subsequent rise regardless of the amount of sodium appearing in the urine. Of thirteen patients tested two to five times, twelve had recurrence of the zenith within a single 4 h period on retesting, despite differences in sodium intake, basal blood pressure, and mean plasma renin activity. Peaks of lesser magnitude were also frequently noted, most commonly at 1000 h and 1800-2000 h. Minimum PRA values were not restricted to a particular time of day and did not generally recur at the same time upon retesting. The mean ratio of maximum to minimum PRA in each study was 246% +/- 18.3% (+/- 1 SEM). The circadian rhythm of renin appears to be independent of known renal mechanisms responsible for regulating renin release. It is possible that this rhythm is controlled by the central nervous system.

Plasma renin activity (PRA) was measured every 4 h during a 24-h period of continuous recumbency in 10 patients with essential hypertension. All had maximum values at 12 midnight, 4 AM or 8 AM. Analysis of our date and that of others indicates that in some patients with "low renin" hypertension (LRH) these noctural peaks are of normal magnitude, occasionally exceeding values obtained after four hours of erect posture. Sleep-induced renin release in these patients is not suppressed despite blunted responses to other stimuli. This suggests that the ability to synthesize and release renin may be normal in these patients. Such peaks were not obserived in all LRH subjects, however. The area enclosed by the recumbent PRA curve was also normal in some, but not all patients with LRH. Low renin hypertension may not be a homogeneous disorder.

Renal para-aminohippurate (PAH) clearances were predicted in 16 kidneys of eight hypertensive patients with renal artery stenosis, pyelonephritis, or obstructive nephropathy, without individual ureteral catheterization. Predictions of left or right kidney clearance (CL or CR) were based on roentgenographic renal frontal areas (A), on total PAH clearances (CT), and on individual PAH extractions (E) measured at renal vein catheterization according to the formula (formula: see text). When these patients underwent ureteral catheterization for diagnostic reasons, individual PAH clearances were measured and ranged from 22 to 286 cm3/min. After correction for differences in total PAH clearance on the two occasions, predicted and individually measured values corresponded closely along a line of identity. The 95% confidence limit (+/- 2 SEM) for predictions of individual PAH clearance was approximately +/- 38 cm3/min and for percet of total PAH clearance distributed to left or right kidney, +/- 6%. Individual renal PAH clearances can therefore be predicted at renal vein catheterization with acceptable error. Thus, the substantially invasive procedure of ureteral catheterization is not required to ascertain left and right kidney PAH clearance in patients already at risk from renal disease.