Effect of RpoN, RpoS and LuxS Pathways on the Biofilm Formation and Antibiotic Sensitivity of Borrelia burgdorferi

Borrelia burgdorferi, the causative agent of Lyme disease, is capable of forming biofilm in vivo and in vitro, a structure well known for its resistance to antimicrobial agents. For the formation of biofilm, signaling processes are required to communicate with the surrounding environment such as it was shown for the RpoN—RpoS alternative sigma factor and for the LuxS quorum-sensing pathways. Therefore, in this study, the wild-type B. burgdorferi and different mutant strains lacking RpoN, RpoS, and LuxS genes were studied for their growth characteristic and development of biofilm structures and markers as well as for their antibiotic sensitivity. Our results showed that all three mutants formed small, loosely formed aggregates, which expressed previously identified Borrelia biofilm markers such as alginate, extracellular DNA, and calcium. All three mutants had significantly different sensitivity to doxycyline in the early log phase spirochete cultures; however, in the biofilm rich stationary cultures, only LuxS mutant showed increased sensitivity to doxycyline compared to the wild-type strain. Our findings indicate that all three mutants have some effect on Borrelia biofilm, but the most dramatic effect was found with LuxS mutant, suggesting that the quorum-sensing pathway plays an important role of Borrelia biofilm formation and antibiotic sensitivity

Effects of salinity and alkalinity on growth and survival of all-male giant freshwater prawn (Macrobrachium rosenbergii De Man, 1879) juveniles

All-male giant freshwater prawns (AMGFPs) have been a popular crop cultivated in the Mekong Delta, Vietnam, due to their proven production efficiency compared to all-female or mixed-sex prawn cultures. However, the crucial water quality factors impacting AMGFP aquaculture efficiency have yet to be elaborately investigated. Two separate experiments were randomly arranged with three replicates to evaluate the effects of salinity or alkalinity on the growth and survival of AMGFP juveniles during the grow-out period. The results show that the prawn survival rate in the salinity range of 0–15‰ varied from 66.1 to 74.8％ and in a salinity range of 0–5‰ was relatively low compared to the range of 10-15‰; however, the difference was not significant among salinities after 90 days of culture (p > 0.05). All the prawn growth performance parameters significantly decreased with increasing salinities of 0, 5, 10, and 15‰ after 30, 60, and 90 days of culture (p 0.05), and both were significantly higher than those at salinities of 10 and 15‰ (p < 0.05) after 90 days of culture. In addition, the survival rate reached 82.5–84.4％ and did not significantly differ among alkalinities of 80, 100, 120, 140, and 160 mgCaCO3 L−1. However, the growth performance parameters and yield of AMGFPs at an alkalinity of 160 mg L−1 were significantly higher than those at lower alkalinities (80, 100, 120, and 140 mg CaCO3 L−1) after 90 days of culture. Therefore, it is recommended that a salinity range of 0–5‰ and alkalinity of 160 mgCaCO3 L−1 is optimal for the growth-out culture of AMGFP juveniles

Characterization of Biofilm Formation by Borrelia burgdorferi In Vitro

Borrelia burgdorferi, the causative agent of Lyme disease, has long been known to be capable of forming aggregates and colonies. It was recently demonstrated that Borrelia burgdorferi aggregate formation dramatically changes the in vitro response to hostile environments by this pathogen. In this study, we investigated the hypothesis that these aggregates are indeed biofilms, structures whose resistance to unfavorable conditions are well documented. We studied Borrelia burgdorferi for several known hallmark features of biofilm, including structural rearrangements in the aggregates, variations in development on various substrate matrices and secretion of a protective extracellular polymeric substance (EPS) matrix using several modes of microscopic, cell and molecular biology techniques. The atomic force microscopic results provided evidence that multilevel rearrangements take place at different stages of aggregate development, producing a complex, continuously rearranging structure. Our results also demonstrated that Borrelia burgdorferi is capable of developing aggregates on different abiotic and biotic substrates, and is also capable of forming floating aggregates. Analyzing the extracellular substance of the aggregates for potential exopolysaccharides revealed the existence of both sulfated and non-sulfated/carboxylated substrates, predominately composed of an alginate with calcium and extracellular DNA present. In summary, we have found substantial evidence that Borrelia burgdorferi is capable of forming biofilm in vitro. Biofilm formation by Borrelia species might play an important role in their survival in diverse environmental conditions by providing refuge to individual cells

TextANIMAR: Text-based 3D Animal Fine-Grained Retrieval

3D object retrieval is an important yet challenging task, which has drawn more and more attention in recent years. While existing approaches have made strides in addressing this issue, they are often limited to restricted settings such as image and sketch queries, which are often unfriendly interactions for common users. In order to overcome these limitations, this paper presents a novel SHREC challenge track focusing on text-based fine-grained retrieval of 3D animal models. Unlike previous SHREC challenge tracks, the proposed task is considerably more challenging, requiring participants to develop innovative approaches to tackle the problem of text-based retrieval. Despite the increased difficulty, we believe that this task has the potential to drive useful applications in practice and facilitate more intuitive interactions with 3D objects. Five groups participated in our competition, submitting a total of 114 runs. While the results obtained in our competition are satisfactory, we note that the challenges presented by this task are far from being fully solved. As such, we provide insights into potential areas for future research and improvements. We believe that we can help push the boundaries of 3D object retrieval and facilitate more user-friendly interactions via vision-language technologies.Comment: arXiv admin note: text overlap with arXiv:2304.0573

Growth and survival rates of domesticated and non-domesticated breeding stocks of Penaeus monodon Fabricius, 1798 cultured in ponds and tanks

Sourced breeders from domesticated broodstocks have played an essential role in the steady development of shrimp culture in many countries. In the present study, two experiments were performed in Tra Vinh province, Vietnam, to compare the culturing benefits of sourced breeding stocks from domesticated and non-domesticated Penaeus monodon broodstock. The first 90-day experiment was randomly arranged with three repetitions in six earthen ponds (1,500–2,000 m2). Experimental shrimp (PL12) were stocked at a density of 20 ind. m−2. The second experiment was randomly designed with three repetitions in six composite tanks (6.0 m3). PL15 of experimental shrimp were cultured at a density of 30 ind. m−2 for 120 days. Grobest pellet feed (40 % protein) was used in both experiments. At experiment termination, the mean weight (26.09 g) and length (15.68 cm) under pond culture, as well as respective values of 15.57 g, and 13.21 cm under tank culture, for D-shrimp were significantly higher than those of W-shrimp (p<0.05). Similarly, the survival rate (84.33 %), FCR (0.98), and yield (3,558 kg ha−1) under pond culture, as well as the survival rate (87.59 %) and yield (470 g m−3) under tank culture, of D-shrimp were significantly better than those of W-shrimp (p<0.05). These results prove that the grow-out culture of shrimp postlarvae from domesticated broodstocks resulted in superior performance to those from wild broodstocks

Characterization of Biofilm Formation by <em>Borrelia burgdorferi In Vitro</em>

<div><p><em>Borrelia burgdorferi</em>, the causative agent of Lyme disease, has long been known to be capable of forming aggregates and colonies. It was recently demonstrated that <em>Borrelia burgdorferi</em> aggregate formation dramatically changes the <em>in vitro</em> response to hostile environments by this pathogen. In this study, we investigated the hypothesis that these aggregates are indeed biofilms, structures whose resistance to unfavorable conditions are well documented. We studied <em>Borrelia burgdorferi</em> for several known hallmark features of biofilm, including structural rearrangements in the aggregates, variations in development on various substrate matrices and secretion of a protective extracellular polymeric substance (EPS) matrix using several modes of microscopic, cell and molecular biology techniques. The atomic force microscopic results provided evidence that multilevel rearrangements take place at different stages of aggregate development, producing a complex, continuously rearranging structure. Our results also demonstrated that <em>Borrelia burgdorferi</em> is capable of developing aggregates on different abiotic and biotic substrates, and is also capable of forming floating aggregates. Analyzing the extracellular substance of the aggregates for potential exopolysaccharides revealed the existence of both sulfated and non-sulfated/carboxylated substrates, predominately composed of an alginate with calcium and extracellular DNA present. In summary, we have found substantial evidence that <em>Borrelia burgdorferi</em> is capable of forming biofilm <em>in vitro.</em> Biofilm formation by <em>Borrelia</em> species might play an important role in their survival in diverse environmental conditions by providing refuge to individual cells.</p> </div

<i>Borrelia burgdorferi</i> B31 strain large aggregate surrounded by individual spirochetes and several small aggregates stained with the calcium-detecting stain Alizarin.

<p>Red coloration indicates presence of calcium, by differential interference contrast (Panel A) and dark field microscopy (Panel B). White arrows indicate unstained spirochetes and small aggregates. 400× magnification.</p

Three-dimensional AFM images of <i>Borrelia burgdorferi</i> B31 strain early aggregates on agarose substrate.

<p>The preparation of <i>Borrelia burgdorferi</i> cells on mica is described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0048277#s4" target="_blank">Materials and Methods</a>. The sample was scanned at 0.3 Hz using contact mode. A: The original AFM image produced with NanoRule© software. B: The AFM dataset was converted to a 3D mesh via a custom meshing utility, cleaned with MeshLab open-source software, then imported to Adobe Photoshop and false-color hand-painted with 3D painting tools. White: spirochete bodies; blue: potential EPS matrix; purple: protrusions; and yellow: small round bodies.</p

Representative images of <i>Borrelia burgdorferi</i> B31 strain aggregates in the early (1^st column, 0 to 2 day), middle (2^nd column, 3 to 6 days) and late (3^rd column, 7 to 21 days) stages of development, observed with dark field (A, B, C – 400× magnification); differential interference contrast (D, E, F - 400× magnification); and FITC-band epifluorescence (G, H, I – 400× magnification).

<p>D, F, and I are extended depth of field composites.</p