High-resolution bulked segregant analysis enables candidate gene identification for bacterial wilt resistance in Italian ryegrass (Lolium multiflorum Lam.)

Bacterial wilt, caused by Xanthomonas translucens pv. graminis (Xtg), is a serious disease of economically important forage grasses, including Italian ryegrass (Lolium multiflorum Lam.). A major QTL for resistance to Xtg was previously identified, but the precise location as well as the genetic factors underlying the resistance are yet to be determined. To this end, we applied a bulked segregant analysis (BSA) approach, using whole-genome deep sequencing of pools of the most resistant and most susceptible individuals of a large (n = 7484) biparental F2 population segregating for resistance to Xtg. Using chromosome-level genome assemblies as references, we were able to define a ~300 kb region highly associated with resistance on pseudo-chromosome 4. Further investigation of this region revealed multiple genes with a known role in disease resistance, including genes encoding for Pik2-like disease resistance proteins, cysteine-rich kinases, and RGA4- and RGA5-like disease resistance proteins. Investigation of allele frequencies in the pools and comparative genome analysis in the grandparents of the F2 population revealed that some of these genes contain variants with allele frequencies that correspond to the expected heterozygosity in the resistant grandparent. This study emphasizes the efficacy of combining BSA studies in very large populations with whole genome deep sequencing and high-quality genome assemblies to pinpoint regions associated with a binary trait of interest and accurately define a small set of candidate genes. Furthermore, markers identified in this region hold significant potential for marker-assisted breeding strategies to breed resistance to Xtg in Italian ryegrass cultivars more efficiently.

Reducing AB plasma utilisation through the AB plasma appropriateness index

OBJECTIVES

We hypothesised that there was inappropriate group AB plasma used in our hospital, identifiable by a novel key quality indicator (KQI) and mitigable through massive transfusion protocol (MTP) modification.

BACKGROUND

Group AB plasma is a scarce resource strained by increasing usage worldwide when used as universal donor plasma in non-group AB patients. To reduce inappropriate use and to promote benchmarking to the best practice, we developed the AB plasma appropriateness index (ABAI). ABAI is the ratio of AB plasma transfused to group AB or unknown blood group patients to all AB plasma utilised, where values closer to 1 are better.

METHODS

Data collected included AB plasma disposition by blood group, indications for transfusion, total blood utilisation, patient clinical characteristics and outcomes. ABAI during a 12-month period was retrospectively assessed, which led to implementation of pre-thawed group A plasma instead of group AB plasma for trauma patients starting in July 2017.

RESULTS

The ABAI retrospectively showed inappropriate use in non-group AB patients in our hospital, the majority used to avoid expiry after thaw. When comparing 1-year pre- and post-implementation periods, ABAI improved from 0·464 to 0·900 (P < 0·0001). After exclusion of therapeutic plasma exchange, ABAI still improved (0·486-0·720, P < 0·0001). No differences in the length of stay or mortality associated in 32 patients receiving group A plasma for emergency release were observed.

CONCLUSION

The ABAI is a novel KQI to indicate inappropriate AB plasma usage for quality improvement. This led to thawed A plasma use for MTPs, reducing inappropriate AB plasma usage.

The value of genetic testing for type 2B Von Willebrand disease

Von Willebrand disease (VWD) is an inherited bleeding disorder that may be associated with significant morbidity, but is often a diagnostic challenge. While an appropriate clinical bleeding history suggests the condition, current laboratory screening investigations lack the sensitivity and specificity to confirm the diagnosis in many cases. Recently, much work has gone into characterizing the genetic mutations associated with the various subtypes of VWD. We report a case in which the diagnosis of VWD type 2B was made via genetic testing, illustrating its value as a useful diagnostic tool.

Petrolatum versus Resurfix ointment in the treatment of pressure ulcers

This study compares the therapeutic effects of a new topically applied, nonprescription medication that has been introduced for re-epithelialization of ulcers and erosions of the skin, with petrolatum in treating pressure ulcers of shallow depth (Stage I and Stage II). A 6-week, randomized, double-blind study was performed on 19 patients with Stage I or Stage II pressure ulcers. The patients received either the new nonprescription medication or petrolatum, which served as a control. After the course of the study, the study ointment effected resolution in a majority of pressure ulcers (9 out of 10), while only one out of three ulcers treated with petrolatum resolved in the same time period. These preliminary results show that the study ointment is a safe and effective treatment for Stage I and II pressure ulcers.

Construction and evaluation of a delta cya delta crp Salmonella typhimurium strain expressing avian pathogenic Escherichia coli O78 LPS as a vaccine to prevent airsacculitis in chickens

Avian pathogenic strains of Escherichia coli cause a number of extraintestinal diseases in poultry, including airsacculitis and colisepticemia. Expression of O78 lipopolysaccharide (LPS) is frequently associated with pathogenic isolates. Salmonella, a common poultry contaminant, is a major public health concern. The purpose of this work was to develop an E. coli vaccine for poultry with the use of an attenuated Salmonella typhimurium carrier that would benefit both the bird and the consumer. Orally administered attenuated S. typhimurium delta cya delta crp strains have been shown to provide excellent protection against wild-type Salmonella challenge in chickens. This work describes the construction of a delta cya delta crp derivative of an avian pathogenic S. typhimurium that expresses both the homologous group B determinants (O1,4,5,12) and the heterologous E. coli O78 LPS O antigens. This was accomplished by inserting the E. coli rfb region, which encodes the genes required for O78 expression, into the chromosomal cya gene of S. typhimurium, creating a defined deletion/insertion mutation. A delta crp mutation was introduced in a subsequent step. Expression of both O antigens was stable in vitro and in vivo. Vaccination of white leghorn chicks at day of hatch and 14 days with the recombinant vaccine strain induced serum immune responses against both S. typhimurium and E. coli LPS and protected the birds against subsequent challenge with an avian pathogenic E. coli O78 strain. Introduction of a mutation in rfc, which encodes the O antigen polymerase, reduced the chain length of the S. typhimurium LPS without affecting the expression of O78. The rfc mutation further enhanced the ability of the vaccine strain to protect chickens against E. coli challenge.

Determination of absorption characteristics of AG337, a novel thymidylate synthase inhibitor, using a perfused rat intestinal model

The purpose of this study was to determine the intestinal absorption characteristics of AG337, a mechanism-based inhibitor of thymidylate synthase, using a perfused rat intestinal model. Effects of site, pH, temperature, concentration, Na+, and inhibitors on the absorption of AG337 were determined, after the compound was shown to be stable in buffers of various pH, blank perfusate, and intestinal homogenate. The results indicated that absorption of AG337 was temperature-, pH-, Na+-, concentration-, and site-dependent. The best site of absorption is duodenum, where the absorption was 3-10 times (p < 0. 05) higher than absorption at jejunum, ileum, and colon. Among the four pH's studied, the best was at pH 6.5 (p < 0.05). Absorption was 80% lower in the absence of Na+, and 75% lower when the temperature of the perfusate was decreased to 4 degreesC. Permeability of AG337 also decreased about 75% when the concentration was raised to 100 microM. These results suggest that a nutrient carrier may be involved in the transport of AG337. To determine the carrier responsible for the absorption of AG337, its absorption was determined in the presence of various inhibitors at different concentrations. The results indicated that transport of AG337 was inhibited significantly (p < 0.01) by 100 microM of adenine, hypoxanthine, and xanthine. The transport was also inhibited significantly (p < 0.01) by a mixture of 100 microM each of adenine, hypoxanthine, and xanthine, but not by a mixture of 100 microM each of thymine and uracil. A higher concentration of hypoxanthine resulted in increased inhibition. In contrast, prototypical inhibitors of nucleoside transporter, dipyridamole and nitrobenzylthioinosine (NBMPR), did not significantly decrease the transport of AG337. The results also showed that absorption of AG337 had a significant nonsaturable component, with a nonsaturable Pw of 0.8. In conclusion, absorption of AG337 in the rat intestine has been shown to be mainly via a purine base carrier with a significant nonsaturable component.

Characterization of cotJ, a sigma E-controlled operon affecting the polypeptide composition of the coat of Bacillus subtilis spores

The outermost protective structure found in endospores of Bacillus subtilis is a thick protein shell known as the coat, which makes a key contribution to the resistance properties of the mature spore and also plays a role in its interaction with compounds able to trigger germination. The coat is organized as a lamellar inner layer and an electron-dense outer layer and has a complex polypeptide composition. Here we report the cloning and characterization of an operon, cotJ, located at about 62 degrees on the B. subtilis genetic map, whose inactivation results in the production of spores with an altered pattern of coat polypeptides. The cotJ operon was identified by screening a random library of lacZ transcriptional fusions for a conditional (inducer-dependent) Lac+ phenotype in cells of a strain in which the structural gene (spoIIGB) for the early-acting, mother-cell-specific transcriptional factor sigma E was placed under the control of the IPTG (isopropyl-beta-D-thiogalactopyranoside)-inducible Pspac promoter. Sequence analysis of cloned DNA from the cotJ region complemented by genetic experiments revealed a tricistronic operon preceded by a strong sigma E-like promoter. Expression of an SP beta-borne cotJ-lacZ fusion commences at around h 2 of sporulation, as does expression of other sigma E-dependent genes, and shows an absolute requirement for sigma E. Studies with double-reporter strains bearing a cotJ-gusA fusion and lacZ fusions to other cot genes confirmed that expression of cotJ is initiated during sporulation prior to activation of genes known to encode coat structural proteins (with the sole exception of cotE). An in vitro-constructed insertion-deletion mutation in cotJ resulted in the formation of spores with no detectable morphological or resistance deficiency. However, examination of the profile of electrophoretically separated spore coat proteins from the null mutant revealed a pattern that was essentially identical to that of a wild-type strain in the range of 12 to 65 kDa, except for polypeptides of 17 and 24 kDa, the putative products of the second (cotJB) and third (cotJC) cistrons of the operon, that were missing or reduced in amount in the coat of the mutant. Polypeptides of the same apparent sizes are detected in spores of a cotE null mutant, on which basis we infer that the products of the cotJ operon are required for the normal formation of the inner layers of the coat or are themselves structural components of the coat. Because the onset of cotJ transcription is temporally coincident with the appearance of active sigma E, we speculate that the cotJ-encoded products may be involved in an early state of coat assembly.

Interference of secretory immunoglobulin A with sorption of oral bacteria to hydroxyapatite

The potential of secretory immunoglobulin A (S-IgA) to interfere with the initial phase of dental plaque formation was studied by using an in vitro method which permits the quantitative determination of the sorption of radiolabeled oral bacterial cells to hydroxyapatite (HA) beads. The importance of specific S-IgA antibodies was evaluated by a comparison of the effect of pure preparations of colostral S-IgA, polymeric myeloma IgA, or preabsorbed S-IgA. Specific antibody molecules bound at the HA surface significantly enhanced the sorption of two Streptococcus sanguis strains. In contrast, HA-bound S-IgA antibodies inhibited the sorption of Streptococcus mitior and Streptococcus salivarius. The same was true for Streptococcus mutans cells, but only when they were propagated in the absence of sucrose. Suspended in saliva, cells of all streptococcal species adhered in significantly lower numbers to HA. Comparative experiments with bacteria suspended in solutions of various preparations of IgA or immunoglobulin-deficient salivas with S-IgA or myeloma IgA added indicated that the adherence inhibition seen with S. Sanguis, S. mitior, S. salivarius, and glucose-grown S. mutans was partly attributable to functions of S-IgA antibodies. Under the in vitro conditions of the study, S-IgA antibodies had no effect on the sorption of sucrose-grown S. mutans, Actinomyces viscosus, and Actinomyces naeslundii to HA. The results indicated that S-IgA can interfere with the sorption of some oral bacteria to HA by several different functions.

Structure of the adenohypophysis in juvenile harp seal, Pagophilus groenlandicus

A study was made of the morphology of the adenohypophysis in immature harp seals and the fine structure of cellular components of the pars tuberalis, pars intermedia and pars distalis was described. The pars intermedia composed 8-15% of the hypophysis and contained colloid filled vesicles similar to those found in the other mammalian species. The pars distalis cells were grouped into more or less well defined regions, thus facilitating the correlation of cellular identification from both light and electron micrographs. Five chromophilic cell types were tentatively identified, one acidophil (putative somatotroph), four basophils (3 putative gonadotrophs and one cell type with the characteristics of both corticotrophs and thyrotrophs) and non-granulated "stellate" cells. The absence of a positive prolactin cell identification was thought to be due to the immaturity of the seals used in the study.