Guide RNA acrobatics: positioning consecutive uridines for pseudouridylation by H/ACA pseudouridylation loops with dual guide capacity

Site-specific pseudouridylation of human ribosomal and spliceosomal RNAs is directed by H/ACA guide RNAs composed of two hairpins carrying internal pseudouridylation guide loops. The distal “antisense” sequences of the pseudouridylation loop base-pair with the target RNA to position two unpaired target nucleotides 5′-UN-3′, including the 5′ substrate U, under the base of the distal stem topping the guide loop. Therefore, each pseudouridylation loop is expected to direct synthesis of a single pseudouridine (Ψ) in the target sequence. However, in this study, genetic depletion and restoration and RNA mutational analyses demonstrate that at least four human H/ACA RNAs (SNORA53, SNORA57, SCARNA8, and SCARNA1) carry pseudouridylation loops supporting efficient and specific synthesis of two consecutive pseudouridines (ΨΨ or ΨNΨ) in the 28S (Ψ3747/Ψ3749), 18S (Ψ1045/Ψ1046), and U2 (Ψ43/Ψ44 and Ψ89/Ψ91) RNAs, respectively. In order to position two substrate Us for pseudouridylation, the dual guide loops form alternative base-pairing interactions with their target RNAs. This remarkable structural flexibility of dual pseudouridylation loops provides an unexpected versatility for RNA-directed pseudouridylation without compromising its efficiency and accuracy. Besides supporting synthesis of at least 6% of human ribosomal and spliceosomal Ψs, evidence indicates that dual pseudouridylation loops also participate in pseudouridylation of yeast and archaeal rRNAs.

Silicone and Pyrocarbon Artificial Finger Joints

Artificial finger joint design has been developed through different stages through the past. PIP (proximal interphalangeal) and MCP (metacarpophalangeal) artificial finger joints have come to replace the amputation and arthrodesis options; although, these artificial joints are still facing challenges related to reactive tissues, reduced range of motion, and flexion and extension deficits. Swanson silicone artificial finger joints are still common due to the physician’s preferability of silicone with the dorsal approach during operation. Nevertheless, other artificial finger joints such as the pyrocarbon implant arthroplasty have also drawn the interests of practitioners. Artificial finger joint has been classified under three major categories which are constrained, unconstrained, and linked design. There are also challenges such as concerns of infections and articular cartilage necrosis associated with attempted retention of vascularity. In addition, one of the main challenges facing the silicone artificial finger joints is the fracture occurring at the distal stem with the hinge. The aim of this paper is to review the different artificial finger joints in one paper as there are few old review papers about them. Further studies need to be done to develop the design and materials of the pyrocarbon and silicone implants to increase the range of motion associated with them and the fatigue life of the silicone implants.

Establishment and Early Regeneration of Stem Cuttings from Chicken Weed (Portulaca quadrifida L.) as Influenced by Soil Types

Differences in the ability of soil are a requirement for early regeneration of a plant. It was a pot experiment carried out at Sokoto in the Sudano Sahelian agro-ecological Zone of Nigeria. The objective was to investigate the regenerative ability of stem cuttings of Chicken weed on different soil type as a strategy for the weed control. The experimental set up was 3 × 7 factorial arrangement in a Completely Randomized Design. The treatments consisted of seven stem cuttings types namely (NLA-D - node leaf attached at distal stem location, NLR-D - node leaf removed from distal stem location, NLA-P- node leaf attached at proximal stem location, NLR-P- node leaf removed from proximal stem location, IN-D - internodes at distal stem location, IN-P- internodes from proximal stem location and SRA- stem roots attached) and three soil textural class (Sandy, Silty clay and Loamy sand). Result revealed that Silty clay recorded highest number of survived plants. Plant height, number of leaves, nodes, internodes and internodes length were greatly favoured by sandy soil. Loamy sand supported the earliness to leaf emergence and flowering. NLA-D supported the early regeneration of the plant in all stem cuttings tested, but earliness to leaf emergence and flowering was better with NLAP. This finding gave information that Chicken weed regenerate profusely and control measures should be administers to save target crop from yield losses. Keywords: distal, proximal, stem cuttings, soil textural class, regeneration

Conservation of a Rare Medicinal Plant: A Case Study of Griffonia simplicifolia (Vahl ex DC) Baill

This study aimed at carrying out the vegetative propagation of Griffonia simplicifolia. This was achieved by growing nodal and stem cuttings of G. simplicifolia using two types of soils under varying environmental conditions including open area and humidity propagator. This revealed that terminal nodal stem cuttings showed the best growth forms in terms of shoot development as well as root development when subjected to open area and topsoil. However, when subjected to the humid propagator and river sand, the distal stem cuttings gave the best growth forms thereby promoting shoot and root development. Hence, it is concluded that the terminal nodes are the best parts to be used for the propagation of G. simplicifolia and the best growth medium is river sand. Furthermore, this research demonstrates that G. simplicifolia can be reproduced through macro propagation using stem cuttings and it can be seen as a basis for conservation and other breeding research on G. simplicifolia.

Production of callus and roots from lateral meristems of Loeselia mexicana

<p><strong>Background</strong>: <em>Loeselia mexicana</em>, known as Mexican false calico, or <em>espinosilla</em> in Spanish, is a widely distributed secondary forest plant with a significant number of medicinal and cosmetic uses. This species is threatened by the lack of regulation over collection methods and changes in land use. <em>In vitro</em> culture could be used to preserve the species by shoot induction, callus production and cell-suspension to obtain secondary metabolites; this would reduce the need to affect wild populations.</p><p><strong>Hypothesis</strong>: A combination of cytokinins and auxins can induce structural development in the plant, promoting the formation of shoots, roots or callus <em>in vitro</em>. By applying this combination to <em>L. mexicana</em> stem segments, we expected to observe new shoots or callus.</p><p><strong>Study site and dates</strong>: “El Teuhtli” volcano, Xochimilco; from June 2015 to February 2016.</p><p><strong>Methods</strong>: Distal stems cuttings were used as explants. They were disinfected with 1 % soap, 0.6 sodium hypochlorite and 70 % ethanol, and rinsed with distilled water. Two different times of disinfection with ethanol were tested. The distal stem segments were then planted in solid MS medium with 3, 5 or 7 mg L^-1 KIN combined with 3 mg L^-1 NAA, and 2 % AC.</p><p><strong>Results</strong>: A favorable response was observed in the treatment with 5 mg L^-1 KIN and 3 mg L^-1 NAA, which produced green callus with root in five weeks. Furthermore, a lower explant mortality rate was achieved, 46.66 % in three weeks, with a shorter disinfection time.</p><strong>Conclusions</strong>: Disinfection time is important for this species, and callus production is possible.

Sites of fractures in explanted NeuFlex® silicone metacarpophalangeal joint prostheses

Single-piece silicone implants dominate metacarpophalangeal joint arthroplasty. The NeuFlex® implant was introduced to improve on the clinical performance of other silicone implants by having a pre-flexed hinge. By visually examining a cohort of 30 explanted NeuFlex® metacarpophalangeal joint prostheses we sought to identify the failure modes of these implants. Seven were not fractured, 11 had fractured across the hinge, nine had fractured at the junction of the distal stem and the hinge, and three showed fractures at both the hinge and at the junction of the distal stem and the hinge. These data may prove helpful in identifying how the performance of single-piece silicone implant designs can be improved.

A TREATMENT OPTION FOR THE DISTAL FORM OF HYPOSPADIA WITH THE USE OF F-II TECHNIQUES (HODGSON-II MODIFICATION)

Introduction. At the moment present, the problem of choosing the method of correction of distal hypospadias due to persistent numerous postoperative complications has not been completely solved. The most frequent complications are fistulas, stenoses and lysis of neo-urethra. Distal hypospadias is divided into distal stem, coronary and capitate. Features of the anatomical structure of the head, prep and meatus in children with hypospadia are often explained by a deficit of plastic material, which can lead to mistakes in the choice of the method of urethroplasty. The current principles of plastic surgery still do not completely eliminate postoperative complications. Material and methods. Since 2004, due to using the F-II procedure 208 operations have been performed without complications mentioned above. At the moment, the long-term results are being investigated. Results. Prolonged search for the optimal approach for the correction of distal forms of hypospadias suggests the need to modify the Hodgson-II technique and introduce it into clinical practice. In this article, the advantages and principal differences of the operation of F-II in comparison with Hodgson-II modification, a brief literary reference about the current world studies of the complications of distal urethroplasty are presented. Conclusion. When using the urethroplasty with a displaced prepuce flap according to the F-II procedure, we get an advantage over the stock of plastic material in comparison with urethroplasty by local tissues. Compared with the Hodgson technique, we get the best cosmetic and functional result.