Wing Hearts in Four-Winged Ultrabithorax-mutant Flies—the role of Hox genes in wing heart specification

Wings are probably the most advanced evolutionary novelty in insects. The development of wings requires the activity of so-called wing hearts located in the scutellum of the thorax. Immediately after the imaginal ecdysis, these accessory circulatory organs remove haemolymph and apoptotic epidermal cells from the premature wing through their pumping action. This clearing process is essential for the formation of functional wing blades. Mutant Drosophila that lack intact wing hearts are flightless and display malformed wings. The embryonic wing heart progenitors originate from two adjacent parasegments corresponding to the later thoracic segments T2 and T3. However, the adult dipterian fly harbors only one pair of wing hearts and also only one pair of wings located in thoracic segment T2. Here we show, that the specification of wing heart progenitors depends on the regulatory activity of the Hox gene Ultrabithorax. Furthermore, we analysed the development of four wing hearts in the famous four-winged Ultrabithorax (Ubx) mutant, which was first discovered by Ed Lewis in the 1970s. In these flies, the third thoracic segment (T3) is transformed into a second thoracic segment (HT2). This results in a second pair of wings instead of the club-shaped halteres normally formed by T3. We show that a second pair of wild-type wing hearts is formed in the four-winged fly and that all wing hearts originate from the wild-type progenitor cells.

Predictive Model of Cerebrospinal Fluid Leakage After Posterior Circumferential Decompression for Thoracic Ossification of Posterior Longitudinal Ligament

Background: Cerebrospinal fluid leakage(CSFL) is one of the most common complications after posterior transarticular osteotomy and circumferential decompression for thoracic ossification of posterior longitudinal ligament(OPLL). It is of great usefulness If the cerebrospinal fluid leakage can be predicted preoperatively. These predictors help to attract the attention of the surgeon in advance and warn the patient. Therefore, the aim of this study is to find out the factors that can predict the CSFL prior to operation and try to build a predictive model.Methods: A total of 61 patients with thoracic OPLL underwent posterior transarticular osteotomy and circumferential decompression from August 2015 to June 2020 in our hospital were included in this study, including 29 males and 32 females. The patients were divided into CSLF group and non-CSFL group according to whether they suffered cerebrospinal fluid leakage. Univariate analysis was used to identify possible predictors in Demographic characteristics, clinical and radiological data. A logistic regression model was developed by multivariate analyses to predict probability of CSFL. Model validation was done using the receiver operating characteristic(ROC) curve.Results: The incidence of CSFL was 31.1%, including 7 males and 12 females, with an average age of 49.8 ±11.4 years. The mean drainage indwelling time in CSFL group was 5.6±1.0 days, which was significantly higher than that in non-CSFL group (4.2±1.3 days, P < 0.001). The mean length of hospital stay was 16.3±6.3 days, slightly higher than that of the non-CSF group (15.8±6.7 days), but there was no statistical difference (P=0.77). Among them, 12 patients (63.2%) suffered low intracranial pressure manifested as headache; 1 patient (5.3%) had cerebrospinal fluid outflow from the incision, and the wound healed successfully after debridement.1 patient (5.3%) was re-admitted to the hospital due to fever after 3 weeks, considering deep wound effusion and pleural effusion. The wound effusion was found to be cured after 2 weeks of anti-infective treatment. Univariate regression analysis showed statistical differences (P<0.05) in smoking history, segment of circumferential decompression, combined with ossification of the ligamentum flavum (OLF), number of laminectomy, occupying ratio and OPLL base ratio. Multivariate regression model showed smoking history (OR=30.1, P=0.003), the upper thoracic segment (OR= 188.0, P= 0.002), the middle thoracic segment (OR= 57.4, P= 0.005) and OPLL base ratio (OR=1.3, P=0.007) were the predictors of CSFL. The ROC curve was in the upper left corner (area under the curve = 0.955, 95% CI 0.91-1.00, P< 0.001), indicating good predictability of the model.Conclusion: The predictive model established in this study has a high predictive effect. When the patients with thoracic OPLL have smoking history or the segment of circumferential decompression is located in the upper or middle thoracic spine or the OPLL has a wide base, the operator should be highly alert to the possibility of postoperative CSFL and warn the patient before surgery. Evidence level: level II-2

New Technique for Intrathoracic Implantation of Extraluminal Spiral Prostheses in the Trachea

Background: Extraluminal surgical procedures for intrathoracic tracheal collapse in dogs are not routinely performed. The patients are normally treated with different drugs or by intraluminal stents. However, in more severe cases, drug treatment does not always have good outcomes, and intraluminal prostheses can be correlated to several postoperative problems. In order to obtain better results, we aimed to develop a surgical technique for implantation of a new extraluminal helical prosthesis in the thoracic segment of the trachea through cervical access, associated with pneumatic mediastinoscopy for certification of the technique and minimization of possible complications.Materials, Methods & Results: Seven canine corpses (CCs) from non-traumatic death, weighing between 2 and 7 kg, were used. A ventral cervical approach to the trachea was associated with blunt mediastinal dissection. Trans cervical pneumatic mediastinoscopy was used for evaluation of the dissection and location of the implant. These were compared with the necropsy findings by the exact Wilcoxon two-sample test, with P < 0.05. The results of necropsy and mediastinoscopy did not present significant differences at P < 0.05. During the examinations, the presence of some mediastinal visceral lesions caused by the prosthesis, the integrity of the mediastinum and possible lesions to RLN and blood vessels (BV) were analyzed. We also investigated the location of the distal part of the prosthesis in the thoracic segment of the trachea and its dissection. To evaluate the technique, statistical comparison was made between mediastinoscopy and necropsy findings. The data were compared by the Wilcoxon test at 5% probability. The tracheas of all CCs were efficiently dissected, but in some cases problems that can happen during the procedure were noticed. This was checked by mediastinoscopy and confirmed by necropsy. The median of the scores was 1 (good dissection and visualization), with variance of zero for mediastinoscopy and 0.14 for necropsy. In the mediastinoscopy of one CC, the prosthesis crossed the tracheal bifurcation, involving the posterior vessels of this region, which was confirmed by necropsy. However, the dissection showed no vascular lesions. The integrity of the mediastinum was assessed only by mediastinoscopy. There was no impairment caused by any of the procedures performed. This resulted in a median score of 1 (integrity) with zero variance. When the positioning of the prosthesis was evaluated in relation to the tracheal bifurcation, identical values were obtained by both methods. The median score was 1, with variance of 0.62. No statistical differences were found between the two evaluation methods for the analyzed variables. This demonstrates the strong potential of the proposed evaluation techniques.Discussion: Our results show that the execution of the technique is possible, but some complications may occur. Mediastinoscopy as an evaluation procedure can pose some complications, these considerations are important, but by using technique proposed in this study, these factors are minimized due to the ease of technical implantation of the extraluminal tracheal stent, without the need for several instruments competing in the inflated mediastinal space. We concluded that the technique is viable and a safe method with minimal invasion for investigation and treatment of mediastinal diseases, presenting low impairment of the paratracheal structures, and that mediastinoscopy can be used as a transoperative evaluation method to minimize complications.

Ubx orchestrates tissue identity through regional and bidirectional changes to chromatin accessibility

Hox proteins are homeodomain transcription factors that diversify serially homologous segments along the animal body axis, as revealed by the classic bithorax phenotype of Drosophila melanogaster where mutations in Ultrabithorax (Ubx) transform the third thoracic segment into the likeness of the second thoracic segment. To specify segment identity we show that Ubx both increases and decreases chromatin accessibility, coinciding with its role as both an activator and repressor of transcription. Surprisingly, whether Ubx functions as an activator or repressor differs depending on the proximal-distal position in the segment and the availability of Hox cofactors. Ubx-mediated changes to chromatin accessibility positively and negatively impact the binding of Scalloped (Sd), a transcription factor that is required for appendage development in both segments. These findings reveal how a single Hox protein can modify complex gene regulatory networks to transform the identity of an entire tissue.

Description of brachial plexus of sloth (Bradypus variegatus)

ABSTRACT: The species Bradypus variegatus is known as the common sloth, an endemic mammal from neotropical regions, which has been suffering from devastating anthropogenic activities. Our study aimed to describe the brachial plexus of B. variegates, regarding the origin and distribution of nerves, through the sampling of 10 adult females. Analyses were carried out at the Anatomy Section, “Departamento de Morfologia e Fisiologia Animal”, “Universidade Federal Rural de Pernambuco”, under license no. 034/2015 of the Ethics Committee on the Use of Animals. The results determined that the brachial plexus of the common sloth starts from the fifth cervical spine segment until the second thoracic segment. This area contains the long and suprascapular thoracic nerves, which originate immediately from the medullary segment 5 and 6, respectively, and from the pectoral, subscapular, axillary, radial, musculocutaneous, medial, forearm and ulnar medial cutaneous nerves, arising from a trunk comprised of cervical spine nerves (C) 7, C8, C9, and thoracic (T) 1 and T2. Regarding other wild and domestic animals, different suggestions were observed about the origin of the plexus in B. variegatus, however, the constituent nerves and their innervation areas did not demonstrate any discrepancies.

Two new species of Sabellariidae (Annelida, Polychaeta) from the abyss of eastern Australia

In May–June 2017 an expedition on board RV ‘Investigator’ sampled benthic communities along the lower slope and abyss of eastern Australia from off Tasmania to the Coral Sea. Over 200 sabellariid specimens of the genera Phalacrostemma and Gesaia were collected during the voyage and deposited in the Australian Museum. Here we describe two new species Gesaia csiro n. sp. (4414–4436 m) and Phalacrostemma timoharai n. sp. (1013–1093 m). We did not formally describe another species of Phalacrostemma due to poor condition of the single specimen. Gesaia csiro n. sp. is the first record of the genus from Australian waters (only a planktonic larva attributed to the genus has previously been recorded), and it can be distinguished from other congeners by the smooth surface of inner paleae, distal thecae of outer paleae with long, irregular and expanded distal fringe and circled distal margin. Phalacrostemma timoharai n. sp. differs from congeners by the following combination of characters: presence of the buccal flap, absence of tentacular filament, 18–22 pairs of outer paleae, two pairs of neuropodial cirri on first thoracic segment, and only one pair of lateral lobes on second thoracic segment. Morphological descriptions are accompanied by mitochondrial cytochrome c oxidase subunit 1 (COI) and ribosomal (16S, 18S and 28S) sequence data. A key to all Australian species of sabellariids is given.