The Stability of Hydrogen-Bonded Ion-Pair Complex Unexpectedly Increases with Increasing Solvent Polarity.

The generally observed decrease of the electrostatic energy in the complex with increasing solvent polarity has led to the assumption that the stability of the complexes with ion-pair hydrogen bonds decreases with increasing solvent polarity. Besides, the smaller solvent-accessible surface area (SASA) of the complex in comparison with the isolated subsystems results in a smaller solvation energy of the latter, leading to a destabilization of the complex in the solvent compared to the gas phase. In our study, which combines Nuclear Magnetic Resonance, Infrared Spectroscopy experiments, quantum chemical calculations, and molecular dynamics (MD) simulations, we question the general validity of this statement. We demonstrate that the binding free energy of the ion-pair hydrogen-bonded complex between 2-fluoropropionic acid and n-butylamine (CH3CHFCOO-…NH3But+) increases with increased solvent polarity. This phenomenon is rationalized by a substantial charge transfer between the subsystems that constitute the ion-pair hydrogen-bonded complex. This unexpected finding introduces a new perspective to our understanding of solvation dynamics, emphasizing the interplay between solvent polarity and molecular stability within hydrogen-bonded systems.

Microbial life in slow and stopped lanes.

Microbes in nature often lack nutrients and face extreme or widely fluctuating temperatures, unlike microbes in growth-optimized settings in laboratories that much of the literature examines. Slowed or suspended lives are the norm for microbes. Studying them is important for understanding the consequences of climate change and for addressing fundamental questions about life: are there limits to how slowly a cell's life can progress, and how long cells can remain viable without self-replicating? Recent studies began addressing these questions with single-cell-level measurements and mathematical models. Emerging principles that govern slowed or suspended lives of cells - including lives of dormant spores and microbes at extreme temperatures - are re-defining discrete cellular states as continuums and revealing intracellular dynamics at new timescales. Nearly inactive, lifeless-appearing microbes are transforming our understanding of life.

How do we transport plant species with desiccation-sensitive germplasm in space?

Many useful plant species with potential for plant-based bioregenerative life support systems produce extremophile seeds with tolerance to multiple stressors, including desiccation, which allows for their transport through space in a dried state. However, other valuable species produce desiccation-sensitive seeds or are propagated clonally, and life sciences research in space has not yet addressed the challenge of alternative transport methods in microgravity for such material. Although liquid nitrogen storage is used on Earth for desiccation-sensitive germplasm, it poses atmospheric leakage problems to crewed spacecraft and therefore liquid nitrogen-free cryogenic freezing could be an alternative. Another promising approach is slow growth tissue culture, with subculture intervals extended to months or years through the precise control of the culture environment. Whilst the design of innovative systems for the transport of species with desiccation-sensitive germplasm will be demanding, the prospect still remains for their successful growth beyond Earth.

Culture of Mycobacterium avium subsp. paratuberculosis: challenges, limitations and future prospects.

Mycobacterium avium subsp. paratuberculosis (MAP) causes paratuberculosis (Johne's disease) in ruminants and is suspected to be involved in the development of Crohn's disease and several autoimmune disorders. As such, sensitive and specific MAP detection methods are required to confirm infection in animals and identify potential sources of animal and human exposure. Despite recent developments in immunological and nucleic acid-based detection methods, culture-based detection of MAP remains the 'gold standard' against which the sensitivity and specificity of other detection methods are measured. However, not all culture-based approaches are equivalent in terms of detection capability, which can lead to errors in the evaluation of other detection methods. This review will provide an overview of the chronological development of culture methods for MAP, and will consider the unique growth requirements of MAP, the merits of solid versus liquid culture media, the relative performance of the commonly used MAP culture media, and sample preparation/decontamination protocols for different sample types. The limitations of current MAP culture methods and prospects for improvements are discussed.

RNAi-mediated knockdown of juvenile hormone acid O-methyltransferase disrupts larval development in the oriental fruit fly, Bactrocera dorsalis (Hendel).

The oriental fruit fly, Bactrocera dorsalis (Hendel), is a notoriously agricultural pest that causes serious economic losses to fruits and vegetables. Widespread insecticide resistance in B. dorsalis is a major obstacle in successful control. Therefore, new pest control strategies, such as those targeting specific genes that can block pest development, are urgently needed. In the current study, the function of JHAMT in B. dorsalis was systematically investigated. A methyltransferase gene in B. dorsalis (BdJHAMT) that is homologous to JHAMT of Drosophila melanogaster was cloned firstly. The subsequently spatiotemporal expression analysis indicated that BdJHAMT mRNA was continuously present in the larval stage, declined sharply immediately before pupation, and then increased in the adult. Subcellular localization showed that BdJHAMT was localized in the adult corpora allata and larval intestinal wall cells. The JH III titer in B. dorsalis was closely related to the transcription level of BdJHAMT in different developmental stages. The dsBdJHAMT feeding-based RNAi resulted in a greatly decreased JH III titer that disrupted fly development. The slow growth caused by BdJHAMT silencing was partially rescued by application of the JH mimic, methoprene. These results demonstrated that BdJHAMT was crucial for JH biosynthesis and thus regulated larval development in B. dorsalis, indicating it may serve as a prospective target for the development of novel control strategies against this pest.

Embryonic transcriptome unravels mechanisms and pathways underlying embryonic development with respect to muscle growth, egg production, and plumage formation in native and broiler chickens.

Background: Muscle development, egg production, and plumage colors are different between native and broiler chickens. The study was designed to investigate why improved Aseel (PD4) is colorful, stronger, and grew slowly compared with the control broiler (CB). Methods: A microarray was conducted using the 7th-day embryo (7EB) and 18th-day thigh muscle (18TM) of improved Aseel and broiler, respectively. Also, we have selected 24 Gallus gallus candidate reference genes from NCBI, and total RNA was isolated from the broiler, improved Aseel embryo tissues, and their expression profiles were studied by real-time quantitative PCR (qPCR). Furthermore, microarray data were validated with qPCR using improved Aseel and broiler embryo tissues. Results: In the differential transcripts screening, all the transcripts obtained by microarray of slow and fast growth groups were screened by fold change ≥ 1 and false discovery rate (FDR) ≤ 0.05. In total, 8,069 transcripts were differentially expressed between the 7EB and 18TM of PD4 compared to the CB. A further analysis showed that a high number of transcripts are differentially regulated in the 7EB of PD4 (6,896) and fewer transcripts are differentially regulated (1,173) in the 18TM of PD4 compared to the CB. On the 7th- and 18th-day PD4 embryos, 3,890, 3,006, 745, and 428 transcripts were up- and downregulated, respectively. The commonly up- and downregulated transcripts are 91 and 44 between the 7th- and 18th-day of embryos. In addition, the best housekeeping gene was identified. Furthermore, we validated the differentially expressed genes (DEGs) related to muscle growth, myostatin signaling and development, and fatty acid metabolism genes in PD4 and CB embryo tissues by qPCR, and the results correlated with microarray expression data. Conclusion: Our study identified DEGs that regulate the myostatin signaling and differentiation pathway; glycolysis and gluconeogenesis; fatty acid metabolism; Jak-STAT, mTOR, and TGF-ß signaling pathways; tryptophan metabolism; and PI3K-Akt signaling pathways in PD4. The results revealed that the gene expression architecture is present in the improved Aseel exhibiting embryo growth that will help improve muscle development, differentiation, egg production, protein synthesis, and plumage formation in PD4 native chickens. Our findings may be used as a model for improving the growth in Aseel as well as optimizing the growth in the broiler.

Poultry Meat Quality in Antibiotic Free Production Has Improved by Natural Extract Supplement.

Modern consumers are conscious of the relationship between meat quality and animal welfare. Today, slow-growing chickens are associated with a higher broiler welfare. The present work aims to evaluate the effect of dietary natural extract supplementation with polyphenols and seaweed mixtures (PPE) on breast and thigh muscles quality parameters in Hubbard JA57 slow growth chicken in antibiotic-free production. Five hundred Hubbard female chickens (250 from control and 250 from experimental group) were housed on floor pens (10 pens/treatment, 25 birds/pen) and assigned to two experimental groups: a control group (CON) receiving a commercial diet and another group receiving the same diet supplemented with 0.3% of polyphenols and seaweed mixtures (PPE). Dietary supplementation with PPE did not affect (p > 0.05) growth performances. The breast pH tended to be lower (p = 0.062) in PPE groups. The protein content of breast muscles resulted higher in PPE samples (p < 0.05) than controls. The thigh muscles from PPE group showed a lower (p < 0.05) malondialdehyde content than CON during refrigerated storage. In conclusion, the PPE supplement improves breast muscle protein content and oxidative stability of thigh muscle. This feeding practice is suggested to enhance the nutritional and technological parameters of meat Hubbard slow growth chicken in antibiotic-free production.

Molecular Basis of the Slow Growth of Mycoplasma hominis on Different Energy Sources.

Mycoplasma hominis is an opportunistic urogenital pathogen in vertebrates. It is a non-glycolytic species that produces energy via arginine degradation. Among genital mycoplasmas, M. hominis is the most commonly reported to play a role in systemic infections and can persist in the host for a long time. However, it is unclear how M. hominis proceeds under arginine limitation. The recent metabolic reconstruction of M. hominis has demonstrated its ability to catabolize deoxyribose phosphate to produce ATP. In this study, we cultivated M. hominis on two different energy sources (arginine and thymidine) and demonstrated the differences in growth rate, antibiotic sensitivity, and biofilm formation. Using label-free quantitative proteomics, we compared the proteome of M. hominis under these conditions. A total of 466 proteins were identified from M. hominis, representing approximately 85% of the predicted proteome, while the levels of 94 proteins changed significantly. As expected, we observed changes in the levels of metabolic enzymes. The energy source strongly affects the synthesis of enzymes related to RNA modifications and ribosome assembly. The translocation of lipoproteins and other membrane-associated proteins was also impaired. Our study, the first global characterization of the proteomic switching of M. hominis in arginine-deficiency media, illustrates energy source-dependent control of pathogenicity factors and can help to determine the mechanisms underlying the interaction between the growth rate and fitness of genome-reduced bacteria.

Investigation of Pathogenic Mechanism of Covert Mortality Nodavirus Infection in Penaeus vannamei.

Viral covert mortality disease (VCMD), also known as running mortality syndrome (RMS), is caused by covert mortality nodavirus (CMNV) and has impacted the shrimp farming industry in Asia and Latin America in recent years. The pathogenic mechanism of CMNV infecting Penaeus vannamei was investigated in this study. In the naturally infected shrimp, histopathological and in situ hybridization (ISH) analysis verified that CMNV infection and severe cellar structural damage occurred in almost all cells of the ommatidium. Under transmission electron microscopic (TEM), vacuolation and necrosis, together with numerous CMNV-like particles, could be observed in the cytoplasm of most cell types of the ommatidium. The challenge test showed that a low CMNV infectious dose caused cumulative mortality of 66.7 ± 6.7% and 33.3 ± 3.6% of shrimp in the 31-day outdoor and indoor farming trials, respectively. The shrimp in the infection group grew slower than those in the control group; the percentage of soft-shell individuals in the infection group (42.9%) was much higher than that of the control group (17.1%). The histopathological and ISH examinations of individuals artificially infected with CMNV revealed that severe cellar damage, including vacuolation, karyopyknosis, and structural failure, occurred not only in the cells of the refraction part of the ommatidium, but also in the cells of the nerve enrichment and hormone secretion zones. And the pathological damages were severe in the nerve cells of both the ventral nerve cord and segmental nerve of the pleopods. TEM examination revealed the ultrastructural pathological changes and vast amounts of CMNV-like particles in the above-mentioned tissues. The differential transcriptome analysis showed that the CMNV infection resulted in the significant down-regulated expression of genes of photo-transduction, digestion, absorption, and growth hormones, which might be the reason for the slow growth of shrimp infected by CMNV. This study uncovered unique characteristics of neurotropism of CMNV for the first time and explored the pathogenesis of slow growth and shell softening of P. vannamei caused by CMNV infection.

The role of sigma factor competition in bacterial adaptation under prolonged starvation.

The study of adaptive microbial evolution in the laboratory can illuminate the genetic mechanisms of gaining fitness under a pre-defined set of selection factors. Laboratory evolution of bacteria under long-term starvation has gained importance in recent years because of its ability to uncover adaptive strategies that overcome prolonged nutrient limitation, a condition often encountered by natural microbes. In this evolutionary paradigm, bacteria are maintained in an energy-restricted environment in a growth phase called long-term stationary phase (LTSP). This phase is characterized by a stable, viable population size and highly dynamic genetic changes. Multiple independent iterations of LTSP evolution experiments have given rise to mutants that are slow-growing compared to the ancestor. Although the antagonistic regulation between rapid growth and the stress response is well-known in bacteria (especially Escherichia coli), the growth deficit of many LTSP-adapted mutants has not been explored in detail. In this review, I pinpoint the trade-off between growth and stress response as a dominant driver of evolutionary strategies under prolonged starvation. Focusing on mainly E. coli-based research, I discuss the various affectors and regulators of the competition between sigma factors to occupy their targets on the genome, and assess its effect on growth advantage in stationary phase (GASP). Finally, I comment on some crucial issues that hinder the progress of the field, including identification of novel metabolites in nutrient-depleted media, and the importance of using multidisciplinary research to resolve them.

Comparative Genomic Analysis Reveals Potential Pathogenicity and Slow-Growth Characteristics of Genus Brevundimonas and Description of Brevundimonas pishanensis sp. nov.

The genus Brevundimonas consists of Gram-negative bacteria widely distributed in environment and can cause human infections. However, the genomic characteristics and pathogenicity of Brevundimonas remain poorly studied. Here, the whole-genome features of 24 Brevundimonas type strains were described. Brevundimonas spp. had relatively small genomes (3.13 ± 0.29 Mb) within the family Caulobacteraceae but high G+C contents (67.01 ± 2.19 mol%). Two-dimensional hierarchical clustering divided those genomes into 5 major clades, in which clades II and V contained nine and five species, respectively. Interestingly, phylogenetic analysis showed a one-to-one match between core and accessory genomes, which suggested coevolution of species within the genus Brevundimonas. The unique genes were annotated to biological functions like catalytic activity, signaling and cellular processes, multisubstance metabolism, etc. The majority of Brevundimonas spp. harbored virulence-associated genes icl, tufA, kdsA, htpB, and acpXL, which encoded isocitrate lyase, elongation factor, 2-dehydro-3-deoxyphosphooctonate aldolase, heat shock protein, and acyl carrier protein, respectively. In addition, genomic islands (GIs) and phages/prophages were identified within the Brevundimonas genus. Importantly, a novel Brevundimonas species was identified from the feces of a patient (suffering from diarrhea) by the analyses of biochemical characteristics, phylogenetic tree of 16S rRNA gene, multilocus sequence analysis (MLSA) sequences, and genomic data. The name Brevundimonas pishanensis sp. nov. was proposed, with type strain CHPC 1.3453 (= GDMCC 1.2503T = KCTC 82824T). Brevundimonas spp. also showed obvious slow growth compared with that of Escherichia coli. Our study reveals insights into genomic characteristics and potential virulence-associated genes of Brevundimonas spp., and provides a basis for further intensive study of the pathogenicity of Brevundimonas. IMPORTANCEBrevundimonas spp., a group of bacteria from the family Caulobacteraceae, is associated with nosocomial infections, deserve widespread attention. Our study elucidated genes potentially associated with the pathogenicity of the Brevundimonas genus. We also described some new characteristics of Brevundimonas spp., such as small chromosome size, high G+C content, and slow-growth phenotypes, which made the Brevundimonas genus a good model organism for in-depth studies of growth rate traits. Apart from the comparative analysis of the genomic features of the Brevundimonas genus, we also reported a novel Brevundimonas species, Brevundimonas pishanensis, from the feces of a patient with diarrhea. Our study promotes the understanding of the pathogenicity characteristics of Brevundimonas species bacteria.

Performance of Slow-Growing Chickens Fed with Tenebrio molitor Larval Meal as a Full Replacement for Soybean Meal.

Insect larval meal is an increasingly common protein source in poultry systems. In this study, the effect of replacing soybean meal with Tenebrio molitor larval meal on the performance of slow-growing chickens was assessed. A total of 128 one-day-old chickens (Colorield) were randomly divided into a control group (C) (n = 64), fed with soybean meal, and an experimental group (TM) (n = 64), fed with T. molitor larvae meal. The chicks were slaughtered after 95 days. Three different isoenergetic and isoproteic diets (F1, F2 and F3) were used for each group. The F1 diet resulted in higher body weight gain and higher feed and water intakes in group C, but a lower feed conversion ratio. Contrarily, diets F2 and F3 did not produce differences in the studied parameters between the two groups, except for body weight gain in the case of diet F2, which was highest in group C. Therefore, weight gain and feed and water intakes were significantly higher in group C, but there were no differences in feed conversion ratio or live weight. In conclusion, the total replacement of soybean meal with T. molitor larvae meal resulted in a reduction in feed intake and a consequent reduction in weight. During this period, partial rather than total substitution may be recommended.

Life in the freezer: protein metabolism in Antarctic fish.

Whole-animal, in vivo protein metabolism rates have been reported in temperate and tropical, but not Antarctic fish. Growth in Antarctic species is generally slower than lower latitude species. Protein metabolism data for Antarctic invertebrates show low rates of protein synthesis and unusually high rates of protein degradation. Additionally, in Antarctic fish, increasing evidence suggests a lower frequency of successful folding of nascent proteins and reduced protein stability. This study reports the first whole-animal protein metabolism data for an Antarctic fish. Groups of Antarctic, Harpagifer antarcticus, and temperate, Lipophrys pholis, fish were acclimatized to a range of overlapping water temperatures and food consumption, whole-animal growth and protein metabolism measured. The rates of protein synthesis and growth in Antarctic, but not temperate fish, were relatively insensitive to temperature and were significantly lower in H. antarcticus at 3°C than in L. pholis. Protein degradation was independent of temperature in H. antarcticus and not significantly different to L. pholis at 3°C, while protein synthesis retention efficiency was significantly higher in L. pholis than H. antarcticus at 3°C. These results suggest Antarctic fish degrade a significantly larger proportion of synthesized protein than temperate fish, with fundamental energetic implications for growth at low temperatures.

In pursuit of a better broiler: tibial morphology, breaking strength, and ash content in conventional and slower-growing strains of broiler chickens.

This study was conducted to determine the differences in bone traits in 14 strains of broiler chickens differing in growth rate. The strains encompassed 2 conventional (CONV; ADG0-48 >60 g/d) and 12 slower-growing (SG) strains classified as FAST (ADG0-62 = 53-55 g/d), MOD (ADG0-62 = 50-51 g/d), and SLOW (ADG0-62 <50 g/d), with 4 strains represented in each SG category. A total of 7,216 mixed-sex birds were equally allocated into 164 pens (44 birds/pen; 30 kg/m2) in a randomized incomplete block design, with each strain represented in 8 to 12 pens over 2-3 trials. From each pen, 4 birds (2 males and 2 females) were individually weighed and euthanized at 2 target weights (TWs) according to their time to reach approximately 2.1 kg (TW1: 34 d for CONV and 48 d for SG strains) and 3.2 kg (TW2: 48 d for CONV and 62 d for SG strains). Tibiae samples were dissected, and length and diameter were recorded. Left tibiae were used for tibial breaking strength (TBS) at both TWs and tibial ash at TW2. At TW1, CONV birds' tibiae were narrowest and shortest (P < 0.001), yet had similar TBS compared to the other categories (P > 0.69). At TW2, category (P > 0.50) had no effect on tibial diameter, yet CONV birds had the shortest tibiae (P < 0.001). The CONV birds had greater TBS:BW ratio than FAST and MOD birds at both TWs 1 and 2 (P < 0.039) and similar ash content as the other categories at TW2 (P > 0.220). At 48 d of age, CONV birds had the greatest absolute TBS (P < 0.003), yet lower TBS:BW ratio than SLOW birds (P < 0.001). Tibiae from CONV birds were longer than MOD and SLOW birds, and thicker in diameter than the other categories, yet CONV birds had the lowest dimensions relative to BW (P < 0.001) at 48 d, indicating a negative association between accelerated growth and tibial dimensions. These results indicate that differences in functional abilities among categories may be due to differences in morphometric traits rather than differences in bone strength and mineralization.

In Vitro Propagation, Genetic Assessment, and Medium-Term Conservation of the Coastal Endangered Species Tetraclinis articulata (Vahl) Masters (Cupressaceae) from Adult Trees.

Tetraclinis articulata (Vahl) Masters is an endangered tree growing in coastal and arid environments that is widely exploited by the timber and resin industry, among other applications. In this context, the use of in vitro techniques is highly encouraged for its propagation. We present a protocol for micropropagation using twigs from adult trees as a source of explants. The Schenk and Hildebrandt basal medium (SH) supplemented with 30 g L-1 sucrose, 6.5 g L-1 plant agar, 4.0 mg L-1 6-benzyladenine (BA), and 0.05 mg L-1 1-naphthaleneacetic acid (NAA) provided the optimum multiplication rate (90.48 ± 9.52 explants with basal shoots and 2.58 ± 0.29 basal shoots per explant). Application of activated charcoal (AC) or ½ Knop solution in a liquid overlay produced significantly longer shoots. Supplementation of solid media with indole-3-butyric acid (IBA) or NAA gave low rooting percentages (<17%). Addition of 0.9 g L-1 AC improved rooting (40%) but rooting performance was optimal (66.7%) after a pulse treatment consisting of 4 h immersion in liquid SH medium without growth regulators, followed by 8 weeks of cultivation. Rooted microplants were successfully acclimatized (93.33%) in a peat moss and vermiculite mixture (1:1 v/v ratio). The genetic stability of the in vitro regenerated plantlets was confirmed using the randomly amplified polymorphic DNA (RAPD) technique. Explant survival and growth remained higher than 90% after 28 weeks of cold storage at both 4 °C and 10 °C. The protocol presented here allows for largescale T. articulata production and could be applied for both ex situ conservation strategies and industrial purposes.

In pursuit of a better broiler: carcass traits and muscle myopathies in conventional and slower-growing strains of broiler chickens.

Selection for accelerated growth rate and high breast yield in broiler chickens have been associated with an increase in myopathies, including wooden breast (WB) and white striping (WS). To investigate effects of growth rate on carcass traits and incidence of myopathies, 14 strains were evaluated, encompassing 2 conventional (CONV; strains B and C: ADG0-48 > 60 g/d) and 12 slower-growing (SL) strains. The latter were categorized based on growth rate: FAST (strains F, G, I and M; ADG0-62=53-55 g/d), MOD (strains E, H, O and S; ADG0-62=50-51 g/d), and SLOW (strains D, J, K and N; ADG0-62<50 g/d). In a randomized incomplete block design, 7,216 mixed-sex birds were equally allocated into 164 pens (44 birds/pen; 30 kg/m2), with each strain represented in 8 to 12 pens over 2 to 3 production cycles. From each pen, 4 males and 4 females were processed at 2 Target Weights (TWs) based on their expected time to reach 2.1 kg BW (TW 1: 34 d for CONV; 48 d for SL strains) and 3.2 kg BW (TW 2: 48 d for CONV; 62 d for SL strains). Weights and yields for the carcass, breast, drumsticks, thighs, and wings were obtained; breast fillets were assessed to determine the presence and severity of WB and WS. At both TWs, breast yield was higher as growth rate increased (P < 0.001), with CONV having greater breast yield than other categories. Strain F had the greatest breast yield at both TWs (P < 0.001) within the FAST category. At TW 2, CONV had the greatest incidence of WB and WS (P < 0.001). However, within FAST, strain F had the greatest incidence of myopathies (P < 0.001) at both TWs, exhibiting values as high or as greater than CONV birds. The incidence of WB and WS in strains with differing growth rates but high breast meat yield suggests that the latter may play a major role in the occurrence of these myopathies.

An alternative resource allocation strategy in the chemolithoautotrophic archaeon Methanococcus maripaludis.

Most microorganisms in nature spend the majority of time in a state of slow or zero growth and slow metabolism under limited energy or nutrient flux rather than growing at maximum rates. Yet, most of our knowledge has been derived from studies on fast-growing bacteria. Here, we systematically characterized the physiology of the methanogenic archaeon Methanococcus maripaludis during slow growth. M. maripaludis was grown in continuous culture under energy (formate)-limiting conditions at different dilution rates ranging from 0.09 to 0.002 h-1, the latter corresponding to 1% of its maximum growth rate under laboratory conditions (0.23 h-1). While the specific rate of methanogenesis correlated with growth rate as expected, the fraction of cellular energy used for maintenance increased and the maintenance energy per biomass decreased at slower growth. Notably, proteome allocation between catabolic and anabolic pathways was invariant with growth rate. Unexpectedly, cells maintained their maximum methanogenesis capacity over a wide range of growth rates, except for the lowest rates tested. Cell size, cellular DNA, RNA, and protein content as well as ribosome numbers also were largely invariant with growth rate. A reduced protein synthesis rate during slow growth was achieved by a reduction in ribosome activity rather than via the number of cellular ribosomes. Our data revealed a resource allocation strategy of a methanogenic archaeon during energy limitation that is fundamentally different from commonly studied versatile chemoheterotrophic bacteria such as E. coli.

Papillary glioneuronal tumor growing slowly for 26 years: illustrative case.

BACKGROUND: Papillary glioneuronal tumors (PGNTs) are classified as a type of World Health Organization grade I mixed neuronal-glial tumor. Most PGNTs involve cystic formations with mural nodules and solid components in the cerebral hemispheres, and PGNTs occur mainly in young adults. The long-term prognosis of PGNTs remains unclear. OBSERVATIONS: A 38-year-old male had been diagnosed with an arachnoid cyst associated with epilepsy in a local hospital. The initial magnetic resonance imaging (MRI) study showed the tumor as a heterogeneously enhanced nodule in the left postcentral gyrus. Subsequent MRI studies showed slow growth of the tumor for 26 years. He underwent gross total resection to control his epilepsy. The histopathological findings revealed pseudopapillary structures involving hyalinized blood vessels with a single or pseudostratified layer of cuboidal glial cells with round nuclei and scant cytoplasm. At the periphery of the lesion, Rosenthal fibers and acidophilic granule bodies were observed in the gliotic brain tissue. Immunohistochemically, some interpapillary cells were positive for NeuN. On the basis of these findings, the tumor was diagnosed as a PGNT. LESSONS: This PGNT showed slow growth for 26 years. When recognizing a slowly growing tumor in the cerebral hemispheres of relatively young people that is associated with epileptic seizures, PGNT should be considered as a differential diagnosis.

(p)ppGpp and Its Role in Bacterial Persistence: New Challenges.

Antibiotic failure not only is due to the development of resistance by pathogens but can also often be explained by persistence and tolerance. Persistence and tolerance can be included in the "persistent phenotype," with high relevance for clinics. Two of the most important molecular mechanisms involved in tolerance and persistence are toxin-antitoxin (TA) modules and signaling via guanosine pentaphosphate/tetraphosphate [(p)ppGpp], also known as "magic spot." (p)ppGpp is a very important stress alarmone which orchestrates the stringent response in bacteria; hence, (p)ppGpp is produced during amino acid or fatty acid starvation by proteins belonging to the RelA/SpoT homolog family (RSH). However, (p)ppGpp levels can also accumulate in response to a wide range of signals, including oxygen variation, pH downshift, osmotic shock, temperature shift, or even exposure to darkness. Furthermore, the stringent response is not only involved in responses to environmental stresses (starvation for carbon sources, fatty acids, and phosphates or heat shock), but it is also used in bacterial pathogenesis, host invasion, and antibiotic tolerance and persistence. Given the exhaustive and contradictory literature surrounding the role of (p)ppGpp in bacterial persistence, and with the aim of summarizing what is known so far about the magic spot in this bacterial stage, this review provides new insights into the link between the stringent response and persistence. Moreover, we review some of the innovative treatments that have (p)ppGpp as a target, which are in the spotlight of the scientific community as candidates for effective antipersistence agents.

Natural variation in stress response induced by low CO2 in Arabidopsis thaliana.

Variation in atmospheric carbon dioxide (CO2) concentration can dictate plant growth and development and shape plant evolution. For paired populations of 31 Arabidopsis accessions, respectively, grown under 100 or 380 ppm CO2, we compared phenotypic traits related to vegetative growth and flowering time. Four accessions showed the least variation in measured growth traits between 100 ppm CO2 and 380 ppm CO2 conditions, though all accessions exhibited a dwarf stature with reduced biomass under low CO2. Our comparison of accessions also incorporated the altitude (indicated in meters) above sea level at which they were originally collected. Notably, An-1 (50 m), Est (50 m), Ws-0 (150 m), and Ler-0 (600 m) showed the least differences (lower decrease or increase) between treatments in flowering time, rosette leaf number, specific leaf weight, stomatal density, and less negative δ13C values. When variations for all traits and seedset were considered together, Ws-0 exhibited the least change between treatments. Our results showed that physiological and phenotypic responses to low CO2 varied among these accessions and did not correlate linearly with altitude, thus suggesting that slower growth or smaller stature under ambient CO2 may potentially belie a fitness advantage for sustainable growth under low CO2 availability.