A Rare Case of COVID-19 Presenting as Acalculous Cholecystitis

At its onset, coronavirus disease 2019 (COVID-19) commonly presents with generalized myalgia and upper respiratory symptoms. COVID-19 presenting as acalculous cholecystitis has been rarely described in the literature. The following case presents a patient whose first presentation of COVID-19 was acalculous cholecystitis without respiratory symptoms, critical illness, or severe COVID-19 infection.

Abstract PD1-04: The contribution of rare variants, polygenic risk, and novel candidate genes to the hereditary risk of breast cancer in a large cohort of breast cancer families

Background: Identifying the missing hereditary factors underlying the familial risk of breast cancer could have a major and immediate impact on managing the breast cancer risk for these families.

Methods: We identified candidate breast cancer predisposition genes through whole exome sequencing of BRCAx families and subsequently sequenced up to 1325 genes, along with 76 common low penetrance variants associated with breast cancer, in index cases from 6,000 BRCAx families and 6,000 cancer free women (ethnically matched on principal component analysis).

Results: The role of recently described (PALB2) or suspected (MRE11A) moderately penetrant genes was confirmed. Conversely, the size of the cohort means that the absence of enrichment for loss of function (LoF mutations) provides strong evidence against other reported breast cancer genes (BRIP1, RINT1, RECQL). For further moderate risk variants (in CHEK2, ATM, BRCA2) we observed significant risk modification based on the polygenic risk score (PRS - calculated from the common variant data), with the risk restricted to the co-occurrence of the rare variant and high PRS. Novel candidate genes were identified based on LoF mutations, including NTHL1 (38 cases versus 15 controls, OR 2.5 p=0.002): a member of the base excision repair (BER) pathway. DNA sequencing of the breast carcinomas from 17 heterozygous NTHL1 mutation carriers revealed a strong bias towards a C:G>T:A (C>T) transitions, consistent with a BER defect, which confirmed the recent findings in colorectal carcinomas from bi-allelic NTHL1 mutation carriers. This data extends the cancer predisposition phenotype of NTHL1 to heterozygous carriers. In addition to NTHL1, there are a large number of candidate genes where the ratio of LoF mutations in cases versus controls indicates that they may convey an actionable level of risk; 46 genes (519 families) meet the basic criteria of multiple LoF variants and an OR >2 for cases versus controls – including previously proposed breast cancer genes MRE11A, BLM, MLH1, MYH, FANCD2 and functionally plausible candidates such as MLH3, PARP2 and ATR. Collectively the OR of breast cancer for LoF mutations in this group of genes is 3.3 (95% CI 2.7-3.9, P=3.5x10-41).

Conclusion: Our data shows that the effect of rare variation in established and novel breast cancer genes, along with consideration of the background polygenic risk, together explains a substantial component of the heritable risk of breast cancer in our cohort.

Citation Format: Campbell IG, Li N, Rowley S, Goode D, Devereux L, McInerny S, Grewal N, Lee A, Trainer A, Wong-Brown M, Scott R, Gorringe K, James P. The contribution of rare variants, polygenic risk, and novel candidate genes to the hereditary risk of breast cancer in a large cohort of breast cancer families [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD1-04.

Abstract PD1-07: Population genetic testing for breast cancer susceptibility

Background. Germline mutations in certain genes account for a large proportion of inherited risk for breast and ovarian cancer. The identification of asymptomatic mutation carriers could significantly reduce the incidence of these diseases as active risk management can dramatically reduce the risk of developing cancer.

In most countries, identifying high-risk individuals is based on their family history. In general, a family is first identified because one family member develops cancer and, because of high-risk indicators is referred to a familial cancer centre (FCC). However, current data suggests that many BRCA1 or BRCA2 mutation carriers do not have a remarkable history of cancer in a close relative. Population-based genetic testing would be a far more effective strategy for identification of at-risk individuals. To test the feasibility of such a strategy we are conducting a population genetic testing trial for actionable mutations in 11 breast/ovarian cancer predisposition genes (BRCA1, BRCA2, PALB2, ATM, CDH1, PTEN, STK11, TP53, BRIP1, RAD51C, RAD51D) among 15,000 healthy women from the Australian population.

Methods. All subjects are female participants in the LifePool cohort (www.lifepool.org) who had no personal history of breast or ovarian cancer at the time of DNA collection. Participants found to carry an actionable germline mutation were notified by letter with an invitation to contact the PeterMac telephone genetic counselling service for further information and/or also invited for counselling at an FCC. Only participants with an actionable mutation were notified of their genetic testing result.

Results. Of the 5,557 women tested to date, 40 (0.72%) were carriers of mutations that are currently actionable in the Australian context (BRCA1 n=7, BRCA2 n=15, PALB2 n=15, ATM n=3). All 40 women accepted the invitation to attend a familial cancer centre for formal predictive testing. Less than 20% of the women would have met the minimum threshold for clinical genetic testing under current guidelines. A further 16 participants (0.29%) carried mutations in BRIP1, RAD51C and RAD51D but were not notified of the result as these genes are not currently actionable in Australia. No mutations were identified in CDH1, PTEN, STK11 or TP53.

Conclusions. A relatively large proportion of cancer free-women from Australia carry high-risk mutations in BRCA genes and subsequent uptake of clinical genetic testing was very high. Population-based genetic testing is well accepted and can identify a much larger proportion of the at risk-population than contemporary family history based approaches.

Citation Format: Campbell IG, Rowley S, Devereux L, McInerny S, Grewal N, Young M-A, Lee A, Trainer A, James P. Population genetic testing for breast cancer susceptibility [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD1-07.

A genetic database can be utilized to identify potential biomarkers for biphenotypic hepatocellular carcinoma-cholangiocarcinoma

BACKGROUND

Biphenotypic hepatocellular carcinoma-cholangiocarcinoma (HCC-CC) is an uncommon primary liver neoplasm. Due to limitations in radiologic imaging for the diagnosis of this condition, biopsy is a common method for diagnosis, which is invasive and holds potential complications. To identify alternative means for obtaining the diagnosis and assessing the prognosis of this condition, we evaluated biomarkers for biphenotypic HCC-CC using a genetic database.

METHODS

To evaluate the genetic associations with each variable we utilized GeneCards(®), The Human Gene Compendium (http://www.genecards.org). The results of our search were entered into the Pathway Interaction Database from the National Cancer Institute (PID-NCI) (http://pid.nci.nih.gov), to generate a biomolecule interaction map.

RESULTS

The results of our query yielded 690 genes for HCC, 98 genes for CC and 50 genes for HCC-CC. Genes depicted in this analysis demonstrate the role of hormonal regulation, embryonic development, cell surface adhesion, cytokeratin stability, mucin production, metalloproteinase regulation, Ras signaling, metabolism and apoptosis. Examples of previously described markers included hepatocyte growth factor (HGF), mesenchymal epithelial transition (MET) and Kirsten rat sarcoma viral oncogene homolog (KRAS). Novel markers included phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA), GPC3, choline kinase alpha (CHKA), prostaglandin-endoperoxide synthase 2 (PTGS2), telomerase reverse transcriptase (TERT), myeloid cell leukemia 1 (MCL1) and N-acetyltransferase 2 (NAT2).

CONCLUSIONS

GeneCards is a useful research tool in the genetic analysis of low frequency malignancies. Utilizing this tool we identified several biomarkers are methods for diagnosing HCC-CC. Finally, utilizing these methods, HCC-CC was found to be predominantly a subtype of CC.

The extent of the raphe in bicuspid aortic valves is associated with aortic regurgitation and aortic root dilatation

Background

The clinical course of bicuspid aortic valves (BAVs) is variable. Data on predictors of aortopathy and valvular dysfunction mainly focus on valve morphology.

Aim

To determine whether the presence and extent of the raphe (fusion site of valve leaflets) is associated with the degree of aortopathy and valvular dysfunction in patients with isolated BAV and associated aortic coarctation (CoA).

Methods

Valve morphology and aortic dimensions of 255 BAV patients were evaluated retrospectively by echocardiography.

Results

BAVs with a complete raphe had a significantly higher prevalence of valve dysfunction (especially aortic regurgitation) than BAVs with incomplete raphes (82.9 vs. 66.7 %, p = 0.01). Type 1A BAVs (fusion of right and left coronary leaflets) and complete raphe had larger aortic sinus diameters compared with the rest of the population (37.74 vs. 36.01, p = 0.031). Patients with CoA and type 1A BAV had significantly less valve regurgitation (13.6 vs. 55.8 %, p < 0.001) and smaller diameters of the ascending aorta (33.7 vs. 37.8 mm, p < 0.001) and aortic arch (25.8 vs. 30.2 mm, p < 0.001) than patients with isolated BAV.

Conclusions

Type 1A BAV with complete raphe is associated with more aortic regurgitation and root dilatation. The majority of CoA patients have incomplete raphes, associated with smaller aortic root diameters and less valve regurgitation.

Eighth Joint National Committee (JNC-8) Guidelines and the Outpatient Management of Hypertension in the African-American Population

Background:

Hypertension is a common medical disease, occurring in about one third of young adults and almost two thirds of individuals over the age of 60. With the release of the Eighth Joint National Committee on Prevention, Detection, Evaluation, and Treatment (JNC-8) guidelines, there have been major changes in blood pressure management in the various subgroups.

Aim:

Optimal blood pressure management and markers of end-organ damage in African-American adult patients were compared between patients who were managed according to the JNC-8 hypertension management guidelines and those who were treated with other regimens.

Materials and Methods:

African-American patients aged 18 years or older with an established diagnosis of hypertension were included in the study who were followed up in our internal medicine clinic between January 1, 2013 and December 31, 2103; the data on their systolic and diastolic blood pressure readings, heart rate, body mass index (BMI), age, gender, comorbidities, and medications were recorded. Patients were divided into four groups based on the antihypertensive therapy as follows — Group 1: Diuretic only; Group 2: Calcium channel blocker (CCB) only; Group 3: Diuretic and CCB; Group 4: Other antihypertensive agent. Their blood pressure control, comorbidities, and associated target organ damage were analyzed.

Results:

In all 323 patients, blood pressures were optimally controlled. The majority of the patients (79.6%) were treated with either a diuretic, a CCB, or both. Intergroup comparison analysis showed no statistically significant difference in the mean systolic blood pressure, mean diastolic blood pressure, associated comorbidities, or frequency of target organ damage.

Conclusion:

Although diuretics or CCBs are recommended as first-line agents in African-American patients, we found no significant difference in the optimal control of blood pressure and frequency of end-organ damage compared to management with other agents.

Comparative in vivo evaluation of restoring severely mutilated primary anterior teeth with biological post and crown preparation and reinforced composite restoration

BACKGROUND

This study was designed to compare the success rate of biological and composite restorations when used to replace structural loss of primary anterior teeth using intracanal post for radicular support of the restoration.

MATERIALS AND METHODS

Forty-two patients aged between 3-5 years presenting with early childhood caries (ECC) received at least one or more composite and biological restorations for comparative evaluation. A total of 150 restorations were done (75 biological restorations and 75 composite restorations). The restorations were evaluated single-blind according to a modified USPHS system. Assessment of the patient's response in accepting a biological restoration, psychological impact of the restorations, view of the parents, and peer group reviews, etc. were recorded in a response sheet in presence of the child and the parents.

OBSERVATIONS AND RESULTS

In vivo clinical performance of biological post and crown restorations and intracanal reinforced composite restorations was comparable with respect to shade match, marginal discoloration, marginal integrity, surface finish, gingival health, retention, and recurrent carious lesions. The cost effectiveness of biological restorations was certainly a positive attribute.

CONCLUSION

The biological restoration presented as a cost effective, clinician friendly, less-technique sensitive, and esthetic alternative to commercially available restorative materials used for restoring deciduous teeth affected by ECC.

The effect of fissure morphology and eruption time on penetration and adaptation of pit and fissure sealants: An SEM study

This study was designed to examine the effect of fissure morphology on penetration and adaptation of fissure sealants and their relationship with the eruption time of tooth.

MATERIALS AND METHODS

One hundred and fifty extracted molars and premolars were divided into two groups on the basis of their eruption time. The two groups were further divided into five subgroups on the basis of fissure morphology. An scanning electron microscopic analysis of penetration and adaptation of sealant was done.

OBSERVATIONS AND RESULTS

V- and U-shaped fissures were found to have the maximum penetration. Penetration was very poor for I- and IK-types of fissures. No significant difference in penetration was found in relation to eruption time. Adaptation of sealant was not affected by any of the factors.

CONCLUSION

Even the well-applied sealant does not necessarily provide complete obturation of pits and fissures, thus necessitating periodical clinical observation to determine the success or potential failure of the sealant treatment.

Root canal configuration of deciduous mandibular first molars--an in vitro study

Root canal morphology of deciduous mandibular first molar was studied using roentgenographic and decalcification and clearing methods. Two groups of 15 teeth were formed. In the roentgenographic group, roots of the teeth were separated from the crown at the level of CEJ. Cut roots of the teeth were radiographed from both mesiodistal and buccolingual directions using separate IOPA films. In the decalcification and clearing group, teeth were decalcified and made transparent. Dye was injected later. The roots of the teeth were examined under 10 times for number, curvature, types and additional features of root canals. Deciduous mandibular first molar showed variability in root canal morphology. Four to five root canals were recorded. Majority of the teeth had 1-1 type of root canal anatomy, but 1-2 type anatomy was also reported. Straight, curved and S-shaped canal curvatures were recorded. Horizontal anastomosis, lateral canals and buccolingually broad root canals were also recorded.

Implementation of behaviour management techniques--how well accepted they are today

Dynamic changes in society with working parents and smaller nuclear families have brought about a sea of changes in parental attitudes and anxieties towards their children. This has affected the perception and implementation of behaviour modification techniques by the dentist. Today, the significance of Tell Show Do technique and its efficiency in behaviour modification is questionable. Insistence of parents on conscious sedation is seen to be on the rise. This study aimed to assess the change in the utilization pattern of behaviour management techniques by pediatric dentists of Punjab in the past five years along with identification of change in parental attitude towards these techniques.

A comparative study of microleakage below cemento-enamel junction using light cure and chemically cured glass ionomer cement liners

Posterior composite resins have gained considerable importance over last few years. However, improper placement techniques continue to be a prime cause of failure of these restorations. This study was done to compare the microleakage at the tooth restoration interface extending below cementoenamel junction when posterior composite restorations were placed directly in the cavity or when placed over a glass ionomer cement liner, both chemically cured and light cured. The results have shown that light cured glass ionomer when used as a liner under a composite restoration used below gingival cementum/dentin margin has the best sealing capability.

Retentive [correction of Preventive] efficacy of glass ionomer, zinc phosphate and zinc polycarboxylate luting cements in preformed stainless steel crowns: a comparative clinical study

This study was undertaken to assess the efficacy of three luting cements, namely, glass ionomer, zinc phosphate and zinc polycarboxylate in retainng the preformed stainless steel crowns in-vivo. Twenty subjects, with an indication for restoration of three primary molars with stainless steel crowns, were selected. Sixty teeth were taken up for the study, and twenty crowns were cemented with each of the three luting cements. After an eight month follow up the crowns were assessed for their presence/ absence or "rocking". Statistical analysis was done using Chi-square test. The results have shown no significant difference in retentivity of stainless steel crowns with the use of either of the three luting agents.

Complete genome sequence of Salmonella enterica serovar Typhimurium LT2

Salmonella enterica subspecies I, serovar Typhimurium (S. typhimurium), is a leading cause of human gastroenteritis, and is used as a mouse model of human typhoid fever. The incidence of non-typhoid salmonellosis is increasing worldwide, causing millions of infections and many deaths in the human population each year. Here we sequenced the 4,857-kilobase (kb) chromosome and 94-kb virulence plasmid of S. typhimurium strain LT2. The distribution of close homologues of S. typhimurium LT2 genes in eight related enterobacteria was determined using previously completed genomes of three related bacteria, sample sequencing of both S. enterica serovar Paratyphi A (S. paratyphi A) and Klebsiella pneumoniae, and hybridization of three unsequenced genomes to a microarray of S. typhimurium LT2 genes. Lateral transfer of genes is frequent, with 11% of the S. typhimurium LT2 genes missing from S. enterica serovar Typhi (S. typhi), and 29% missing from Escherichia coli K12. The 352 gene homologues of S. typhimurium LT2 confined to subspecies I of S. enterica-containing most mammalian and bird pathogens-are useful for studies of epidemiology, host specificity and pathogenesis. Most of these homologues were previously unknown, and 50 may be exported to the periplasm or outer membrane, rendering them accessible as therapeutic or vaccine targets.

D-Aspartate oxidase and D-amino acid oxidase are localised in the peroxisomes of terrestrial gastropods

D-Aspartate oxidase and D-amino acid oxidase were found in high activity in the tissues of representative species of terrestrial gastropods. Analytical subcellular fractionation demonstrated that both of these oxidases co-localised with the peroxisome markers, acyl-CoA oxidase and catalase, in the digestive gland homogenate. Electron microscopy of peak peroxisome fractions showed particles of uniform size with generally well preserved variably electron-dense matrices bounded by an apparently single limiting membrane. Many of the particles exhibited a core region of enhanced electron density. Catalase cytochemistry of peak fractions confirmed the peroxisome identity of the organelles. Peroxisome-enriched subcellular fractions were used to investigate the properties of gastropod D-aspartate oxidase and D-amino acid oxidase activities. The substrate and inhibitor specificities of the two activities demonstrated that two distinct enzymes were present analogous to, but not identical to, the equivalent mammalian peroxisomal enzymes.

Gastropod mollusc aliphatic alcohol oxidase: subcellular localisation and properties

The digestive gland and other tissues of several species of terrestrial gastropod mollusc contain an aliphatic alcohol oxidase activity (EC1.1.3.13). The enzyme is FAD dependent, consumes oxygen and generates hydrogen peroxide and the corresponding aldehyde. Saturated primary alcohols are favoured as substrates with octanol preferred with an apparent Km of 3-4 microM. The activity is clearly distinguishable from previously reported molluscan aromatic alcohol oxidase (EC1.1.3.7) on the basis of FAD dependence, sensitivity to heat treatment and high salt concentration and with regard to substrate preferences. The aliphatic alcohol oxidase is membrane associated and most likely localised to the endoplasmic reticulum. Extraction of membranes with 1% Igipal solubilises the enzyme in active form. This enzyme is a further example of an oxidase apparently restricted to molluscs.

Relationship of tongue-thrust swallowing and anterior open bite with articulation disorders: a clinical study

A Paediatric dentist may be the first person consulted for professional advice concerning children with speech problems. A positive significant relationship has been hypothesized by some authors between tongue-thrust swallowing and articulation disorders in children. This study was undertaken to find out whether any articulation disorders are associated with the habit of tongue-thrust swallowing, or is it the type of anterior bite that plays an important role in the normal or abnormal speech production in tongue-thrust swallowers. Forty subjects with tongue-thrust swallowing in the age group of 7-16 years were examined. Of these 20 had normal anterior bite while rest had anterior open bite. A word articulation test was used and word level articulation testing was done for initial, medial and final positions. The sounds tested were: Linguoalveolars, Labiodentals, Linguodentals, Linguopalatals, Bilabials and Linguovelars. The results of the study have indicated that the presence of articulation disorders is strongly associated with the anterior open bite present in tongue-thrust swallowers but a simple, direct relationship between the presence of defective consonant sounds and tongue-thrust swallowing has not been found.

Comparison of sealing efficacy of materials placed in lateral root perforations--an in vitro study

An endodontic perforation interferes with the principal goal of sealing the root canal system. An in vitro study was conducted on comparative efficacy of three materials-Dispersalloy, Cavit and Prisma VLC Dycal when placed in lateral root perforations in cervical third areas. Root canals were prepared and irrigated thoroughly. Perforations were made with No. 2 round bur and sealed with Dispersalloy, Cavit and Prisma VLC Dycal. Dispersalloy Group I showed best sealing ability. Prisma VLC Dycal Group I too was comparable to Dispersalloy Group I in its sealing ability, followed by Cavit Group II, Prisma VLC Dycal Group II, Dispersalloy Group II in that order. Cavit Group I was least effective in sealing perforations.

Zonal rotor purification and characterization of "mannosomes": a tubular membrane system in gastropod mollusc digestive gland

Mannitol oxidase (manox) is an H2O2-generating oxidase apparently unique to molluscs and especially abundant in alimentary tissues. In the digestive gland it is localized to an organelle ("mannosome") that forms an unusual tubular membrane system. We have developed a novel centrifugation procedure for >100-fold purification of these membranes in 20% yield from approximately 30 g of digestive gland of the slug Arion ater. Mannosomes from several other gastropod species are also substantially purified by the procedure. Four successive density gradient separations are employed which minimize structural damage by exploiting near isosmotic conditions early on and by completely avoiding traumatic pelleting and resuspension. Plasma membrane contamination is reduced by digitonin-induced density perturbation. The purified preparation is characterized by a predominant 68-kDa integral membrane protein and retains the in situ appearance of hexagonally arranged tubules with an enveloping outer membrane.

A comparative study of effects of mouth breathing and normal breathing on gingival health in children

The present study was conducted to assess the effects of mouth breathing, lip seal and upper lip coverage on gingival health of children. 240 school children aged 10-14 years were selected irrespective of sex race and socioeconomic status. They were divided into two major groups i.e. mouth breathers and normal breathers. These groups were further subdivided into six sub-groups or categories on the basis of lip seal and upper incisor coverage. Gingival index was found to be higher in the mouth breathers than in the normal breathers in the subjects with incompetent lip seal. Increased lip separation and decreased upper lip coverage were all associated with higher levels of Plaque index and Gingival index. No statistical difference existed between mouth breathers and normal breathers with respect to Plaque index.

Ligand-induced receptor dimerization may be critical for signal transduction by choriogonadotropin

A mechanism of signal transduction by human choriogonadotropin (hCG) has been proposed. Competitive inhibition of the binding of hCG to its receptor by the serine protease inhibitors led to the identification of local structural homology of an extracellular region of the receptor with the reactive site loop of chymotrypsin inhibitor. Synthetic peptides from the extracellular domain of luteinizing hormone-choriogonadotropin (LH/CG) receptor, rationally designed on the basis of this homology, were found to affect hormone-receptor binding and bioactivity. A receptor peptide incorporating one complete structural unit of the leucine-rich repeats motif of the extracellular domain of the receptor significantly increased hCG-receptor binding in a dose-dependent manner. However, the testosterone production in a Leydig cell bioassay was inhibited in the presence of this peptide. The agonistic effect on the hCG-receptor binding and the antagonistic effect on the testosterone production of a receptor peptide suggests the possibility of more than one quasi-equivalent receptor-binding site on the hormone. Hormone-induced receptor oligomerization may therefore be involved in the mechanism of signal transduction by hCG.

A study of toothbrush contamination at different time intervals and comparative effectiveness of various disinfecting solutions in reducing toothbrush contamination

Toothbrush contamination during the procedure of brushing was assessed at different time intervals of usage. A peak value of 100% contamination was found at 1 month interval. Hence, a method suggesting disinfection of the toothbrush was employed by comparing the effectiveness of various disinfecting solutions available in the market so that, the brush does not become a source of potential pathogens.

Computer modelling of the interaction between human choriogonadotropin and its receptor

Primary structural homology between the hormone binding site of the LH/CG receptor and the enzyme binding site of chymotrypsin inhibitor has been identified. This has led to the application of a knowledge-based approach of molecular modelling to describe the interaction of choriogonadotropin (CG) with the LH/CG receptor. A tertiary structural model for the mode of recognition between the hormone and the receptor has been proposed. As in other such processes at the molecular level, the recognition between CG and its receptor is mediated through non-covalent interactions. The specificity of recognition is achieved by complementarity in van der Waals surfaces, hydrogen bonding and non-polar associations. The model shows nine hydrogen bonds between the hormone and the receptor involving polar side chains as well as backbone amine and carbonyl groups. A hydrophobic cluster involving side chain groups at the interface is also important in stabilization of the intermolecular interactions.

The antigenic domain of flagellin from S. paratyphi shares a structural fold with subtilisin

Bacterial flagellin has two domains: the polymerizing domain consisting of N- and C-terminal regions which are partly disordered in the monomeric state; and the central antigenic domain with compact globular structure. The polymerizing domain is highly conserved in flagellins from different species but the antigenic domain is diverse in sequence and size. Whereas the former has direct functional significance for bacterial motility, the latter has not been identified as having a specific function except for defining the distinct serotype of the bacterium. The sequence alignment of flagellin from S. paratyphi with proteins of known three-dimensional structure reveals significant homology of the central 265 residue stretch with the bacterial serine protease, subtilisin. This homology is evident also in the comparison of the predicted secondary structure of flagellin with the observed secondary structural features in subtilisin. The deletions/insertions arising due to optimal alignment of the two proteins occur on the surface loops in the structure. Thus, a domain of S. paratyphi flagellin and subtilisin appear to have similar structural folds.

A gene encoding a protein with seven zinc finger domains acts on the sexual differentiation pathways of Schizosaccharomyces pombe

Byr3 was selected as a multicopy suppressor of the sporulation defects of diploid Schizosaccharomyces pombe cells that lack ras1. Like cells mutant at byr1 and byr2, two genes that encode putative protein kinases and that in multiple copies are also suppressors of the sporulation defects of ras1 null diploid cells, cells mutant at byr3 are viable but defective in conjugation. Nucleic acid sequence indicates byr3 has the capacity to encode a protein with seven zinc finger binding domains, similar in structure to the cellular nucleic acid binding protein (CNBP), a human protein that was identified on the basis of its ability to bind DNA. Expression of CNBP in yeast can partially suppress conjugation defects of cells lacking byr3.