Response of weedy rice (Oryzaspp.) germplasm from Arkansas to glyphosate, glufosinate, and flumioxazin

Weedy rice (Oryzaspp.) is one of the most competitive weeds in rice (Oryza sativaL.) production. Rapid growth, high tillering, enhanced ability to uptake fertilizers, asynchronous maturation, seed shattering, and high seedbank longevity makeOryzaspp. more competitive than cultivated rice and highly persistent.Oryzaspp. may be a source of useful traits for crop improvement such as herbicide tolerance. Greenhouse studies were conducted to evaluate the response of 54Oryzaspp. accessions collected between 2008 and 2009 from Arkansas to glyphosate, glufosinate, and flumioxazin applied at field rates. Rice cultivars ‘CL163’ and ‘REX’ were included for comparison. Accessions B20, B2, and S11 and B49, B51, and S59 showed reduced sensitivity to glyphosate and flumioxazin, respectively. These accessions had less than 40% injury 5 wk after treatment (WAT). Rice cultivars (CL163 and REX) were sensitive to both glyphosate and flumioxazin, with more than 95% plant mortality at 5 WAT. On average, blackhull accessions were more tolerant to glyphosate and flumioxazin than strawhull accessions. Dose–response analysis of B20, B2, and S11 confirmed 3- to 8-fold higher tolerance of these accessions to glyphosate. AllOryzaspp. and cultivated rice were not affected by glufosinate applied at 874 g ai ha−1(1X) and were controlled 100% by 1,311 g ai ha−1(1.5X).Oryzaspp. lines with reduced sensitivity to glyphosate and flumioxazin will be studied further for use in rice crop improvement.

Phenotypic and sexual structure of Mytilus galloprovincialis Lam., cultivated on the mussel-oyster farm in the outer harbor of Sevastopol city (Crimea, Black Sea)

Morphophysiological studies of hydrobionts, and, in particular, mussels cultivated in marine farms, become important for modern hydrobiology. The study of the phenotypic structure of the mussel settlements in the Black Sea is an important aspect of monitoring the state of the mollusk population in changing environmental conditions. Information about patterns of sex realization under certain conditions can be the basis for active management of settlement formation in the cultivation of mollusks. Data about the regularities of sexual maturation of mussels, the stages of maturity of gonads and gametes spawning are also of importance. The aim of the work was to assess the phenotype and sex structure of the mussel populations as well as the stages of gonads maturity of the mussel Mytilus galloprovincialis cultivated on the mussel-oyster farm located in the outer harbor of Sevastopol. Mussels with the size of the shell from 4.9 to 5.4 mm were collected monthly from March 2015 to August 2016 on the studied mussel-oyster farm. Phenotype, sex and stages of gonad maturity were determined in mollusks by standard methods. When determining the frequency of occurrence of mussel phenotype on the mussel-oyster farm, a higher percentage of mollusks with black color shells (Bl) in comparison with whose with brown color shells (Br) was observed, and on average for the studied period the shell phenotype ratio (Bl : Br) was 1.8 : 1 respectively. Data on the sexual structure of M. galloprovincialis on the studied mussel-oyster farm are presented. Average ♂ : ♀ ratio was 2.8 : 1, with the proportion of hermaphrodites reaching 1–6 %. The sex ratio was different every month. In March 2015 it was 1.7 : 1 (♂ : ♀) and by August 2015, while mollusks growing on the mussel’s collector, the share of males reached its maximum (8 : 1). After thinning the mussels on the collector, the sex ratio had stabilized by October 2015 and remained at the level of 2 : 1 until March 2016. The next subsidence of the young and increase of mussels mass on the collector had again led to a significant shift of the mussel sexual structure (7.5 : 1) by May 2016. One of the reasons of the increase in the number of males in the studied mussel-oyster farm is thought to be the high density of mussels in the druse resulting in local hypoxia and poor food accessibility. The analysis of the state of gonads maturity of cultivated mussels showed two peaks of spawning – spring (March, April) and a long autumn one (started in October and continued until early December). Mass reproduction of mussels was observed in the spring when the surface water layer warmed up to 9–12 °C and in the autumn with the decrease of water temperature to 18 °C. The asynchronous maturation of the gonads of M. galloprovincialis of both sexes was observed. Males had greater variability of maturity stages than females. The shift in the ratio of the sexes towards the increase of males share as well as the increase of the number of mussels with black color shell and also the asynchronous maturation of the gonads of M. galloprovincialis on the studied farm can be considered as the ecological and physiological response of mollusks to the environment changes.

The Neural Circuitry and Neurocognitive Development

This chapter focuses on adolescent brain development and associated functional implications. We focus on changes in brain tissue composition, fiber architecture and circuitry, and neurochemistry and discuss how these maturational processes affect adolescent brain functioning, sleep, cognition, and behaviors. Given the substantial developments that occur during adolescence, the effects of puberty and sex hormones on brain structure and function are reviewed, and literature on the effects of substance use on the adolescent brain are covered. The chapter reports on recent neuroimaging studies suggesting that atypical and/or asynchronous maturation patterns may contribute to adolescents’ proclivity for risk taking, heightened emotionality, and the emergence of psychopathology. Finally, future research opportunities are discussed.

Asynchronous maturation of the sexes may limit close inbreeding in a subsocial spider

We studied the temporal patterns of maturation and sexual receptivity of a subsocial spider, Anelosimus cf. jucundus, in southern Arizona. In subsocial spiders, sibling males and females share a common nest for a large portion of their life cycle, often only dispersing short distances close to the mating season. We found that, on average, male A. cf. jucundus matured 9 days earlier than females and that females did not become sexually receptive until 10 days following their final molt to maturity. The periods of sexual receptivity of sibling males and females, therefore, would be separated in time by a significant fraction of an adult male's life cycle. We also found significant asynchrony in maturation dates across nests and nest clusters at the two collection localities. We suggest that these temporal patterns may limit the opportunities for sibling males and females to mate with each other, thus explaining the apparent absence of mechanisms to discriminate against kin as mates in this species.

The fine structure of sporogony in Myxidium zealandicum (Protozoa: Myxosporidia)

Studies of the ultrastructure of the trophozoite (plasmodium) and the process of sporogony and polar capsule development of Myxidium zealandicum from gill and kidney of the North American eel Anguilla rostrata are described. Although the basic steps and characteristics of sporogony are similar to those previously reported for other myxosporidians, we report three new and significant observations in this study: (1) the identification of a uninucleate germ cell for the binucleate sporocyst; (2) the asynchronous maturation of polar capsules within a single sporocyst; and (3) the existence of a mitochondrial layer at the periphery of the Plasmodium that may have a transport function. We also observed cylindrical and spherical structures, either of which might be the primordium of the polar capsule, but we were unable to resolve this problem. These observations are discussed with reference to previous descriptions of myxosporidians.