HORSIC+: An Efficient Post-Quantum Few-Time Signature Scheme

It is well known that conventional digital signature algorithms such as RSA and ECDSA are vulnerable to quantum computing attacks. Hash-based signature schemes are attractive as post-quantum signature schemes in that it is possible to calculate the quantitative security level and the security is proven. SPHINCS is a stateless hash-based signature scheme and introduces HORST few-time signature scheme which is an improvement of HORS. However, HORST as well as HORS suffers from pretty large signature sizes. HORSIC is proposed to reduce the signature size, yet does not provide in-depth security analysis. In this paper, we propose HORSIC+, which is an improvement of HORSIC. HORSIC+ differs from HORSIC in that HORSIC+ does not apply f as a plain function to the signature key, but uses a member of a function family. In addition, HORSIC+ uses the chaining function similar to W-OTS+. These enable the strict security proof without the need for the used function family to be a permutation or collision resistant. HORSIC+ is existentially unforgeable under chosen message attacks, assuming a second-preimage resistant family of undetectable one-way functions and cryptographic hash functions in the random oracle model. HORSIC+ reduces the signature size by as much as 37.5% or 18.75% compared to HORS and by as much as 61.5% or 45.8% compared to HORST for the same security level.

Microbiota composition and evenness predict survival rate of oysters confronted to Pacific Oyster Mortality Syndrome

Pacific Oyster Mortality Syndrome (POMS) affects Crassostrea gigas oysters worldwide and caused important economic losses. Disease dynamics was recently deciphered and revealed a multiple and progressive infection caused by the Ostreid herpesvirus OsHV-1 µVar, triggering an immunosuppression followed by microbiota destabilization and bacteraemia by opportunistic bacterial pathogens. However, it remains unknown if microbiota might participate to oyster protection to POMS, and if microbiota characteristics might be predictive of oyster mortalities. To tackle this issue, we transferred full-sib progenies of resistant and susceptible oyster families from hatchery to the field during a period in favour of POMS. After five days of transplantation, oysters from each family were either sampled for individual microbiota analyses using 16S rRNA gene-metabarcoding or transferred into facilities to record their survival using controlled condition. As expected, all oysters from susceptible families died, and all oysters from the resistant family survived. Quantification of OsHV-1 and bacteria showed that five days of transplantation was long enough to contaminate oysters by POMS, but not for entering the pathogenesis process. Thus, it was possible to compare microbiota characteristics between resistant and susceptible oyster families at the early steps of infection. Strikingly, we found that microbiota evenness and abundances of Cyanobacteria (Subsection III, family I), Mycoplasmataceae, Rhodobacteraceae, and Rhodospirillaceae were significantly different between resistant and susceptible oyster families. We concluded that these microbiota characteristics might predict oyster mortalities.

Resistance of Pinus taeda families under artificial inoculations with diverse fusiform rust pathogen populations and comparison with field trials

Controlled inoculations with 10 bulk inocula of Cronartium quercuum (Berk) Miyabe ex Shirai f.sp. fusiforme were carried out on open-pollinated progeny of 25 fast-growing Pinus taeda L. parents. The parents had a range of breeding values for resistance to fusiform rust in progeny field trials. There were highly significant differences among the half-sib families in response to inoculations, and these differences were very reproducible; the half-sib family-mean heritability of resistance to controlled inoculation was 0.97. All of the families that were susceptible in the field were susceptible in controlled inoculations, and most (12 of 17) of the field-resistant families were resistant in response to controlled inoculations. Significant pathogenic variability was observed among the different bulk inocula, although this accounted for only 1.9% of the total variation. Genetic differences among families within field-resistant or field-susceptible groups accounted for 13.7% of the total variation. The family by inocula interaction was highly significant, but a single field-resistant family contributed 44% of the total family by inocula interaction variance, and two other field-resistant families also showed significant interactions.

Influence of elevated CO2, nitrogen, and Pinus elliottii genotypes on performance of the redheaded pine sawfly, Neodiprion lecontei

Slash pine (Pinus elliottii Engelm. var. elliottii) seedlings were grown in open-top chambers receiving ambient or elevated atmospheric CO2 (~365 or ~720 µL·L–1). Seedlings received low or high soil nitrogen treatments (0.02 or 0.2 mg N·g–1) and represented three families varying in resistance to fusiform rust (Cronartium quercuum (Berk.) Miyabe ex Shirai f. sp. fusiforme (Hedgc. & N. Hunt) Burdsall & G. Snow). Following 18 months of exposure to treatment conditions, current-year needles were fed to larvae of the redheaded pine sawfly (Neodiprion lecontei (Fitch)). Needle N concentration and water content were lower in elevated-CO2 and in low-N treatments. Total phenolics increased under high-CO2 and low-N conditions and were highest in the resistant family. Condensed tannins did not vary on the basis of CO2 or N but were higher in needles from the resistant family. Alterations in needle chemistry were associated with variations in sawfly growth and development. Larvae performed most poorly on the family most resistant to fusiform rust, suggesting that the mechanism for resistance was similar in both cases. Relative consumption rates increased with CO2-enriched needle diets but were depressed for resistant needles, suggesting deterrence from the higher total phenolics in this family. Diets using CO2-enriched needles or resistant needles or needles from low-N fertilization treatments resulted in lower relative growth rates for the larvae. Days to pupation increased for larvae fed CO2-enriched and low-N needles. These results suggest that the redheaded pine sawfly could suffer as the level of atmospheric CO2 continues to rise.

A Canine Model of Familial Mammary Gland Neoplasia

Intact female Beagles from life-span studies in the Lovelace Respiratory Research Institute colony were examined for mammary tumor incidence. The breeding colony, founded in 1963, produced five generations from 28 founder females. After proportional hazards analysis, two maternal families were shown to have markedly different phenotypes, one susceptible and one resistant to mammary neoplasia, as compared with the entire colony. When tumors were subdivided into benign and malignant based on local invasiveness, familial differences in tumor incidence were preserved for each tumor type. Fifty-seven females in the susceptible family developed 149 benign and 39 malignant tumors, and 95 females in the resistant family developed 70 benign and 20 malignant tumors. The ratio of benign to malignant tumors of about 4:1 for both families was higher than expected. Using Kaplan–Meier and log-rank analyses, the susceptible family had a 50% malignant tumor incidence by age 13.6 years, whereas the resistant family did not have a 50% incidence until 17.0 years ( P = 0.0065). Because of marked censoring, Kaplan–Meier analyses could not provide an estimate of the 50% benign tumor incidence; mean incidence age was calculated instead. These estimates for benign tumors for susceptible and resistant families were 10.8 and 13.8 years ( P = 0.0001), respectively. Using χ2 tests, families had no differences in the occurrence of the types of benign ( P = 0.098) or malignant ( P = 0.194) tumors or in the ratio of benign to malignant tumors ( P = 0.778). Immunohistochemical analysis of malignant tumors from both families did not demonstrate differences in p53 mutation rate or p185 erbB-2 expression. These results suggest that 1) genetic factors produce familial differences in the age of onset of both benign and malignant mammary tumors; histologic types do not segregate by family; 2) the ratio of benign to malignant tumors is greater than formerly reported; and 3) neither p53 nor p185 erbB-2 alterations are the basis for the familial predisposition.

Dispersal of Pissodes strobi in putatively resistant white spruce in Vernon, BC

White pine weevil Pissodes strobi behaviour was observed in a five-year-old plantation of white spruce in Vernon, British Columbia. Seasonal weevil-host interactions were monitored in four susceptible and four putatively resistant reciprocal cross family pairs in three of five replicates. Classification of susceptibility to weevil attack was based on previous weevil attack history. Performance of eight reciprocal cross pairs was ranked as a function of visitation, oviposition and brood establishment resulting in top-kill. The four putatively resistant family crosses ranked 1 to 4 for resistance to weevil attack, while the four susceptible crosses were ranked 5 to 8 and were consistently attacked. Seasonal and diurnal weevil movement was monitored using mark-recapture techniques. Diurnally, weevils moved within the tree. Feeding occurred at dawn in the leader and upper laterals after which weevils moved down the tree into the forest floor during the high mid-summer temperatures. Later in the season weevils fed in mid-morning on the leader and on the under-sides of lateral branches. A dispersal index was developed to describe seasonal movement. Weevils did not move far throughout the season. Overall dispersal index for both males and females was less than 0.24 m, suggesting that on average, weevils do not move further than the adjacent tree throughout the season after mating and oviposition. Key words: Dispersal, pest management, Pissodes strobi, resistance, silviculture, white spruce