Intracellular Development of Enterocytozoon, A Unique Microsporidian Found in the Intestine of AIDS Patients

Enterocytozoon was 1st described in 1985, in an AIDS patient with intestinal malabsorption and diarrhea. Since then, additional cases of infection with this organism have been observed, but only in individuals with AIDS and malabsorption. Intestinal tissue biopsies were obtained from a 45-year-old man prior to AIDS diagnosis, again nine months later and then at autopsy two months later. When the biopsies were examined electron microscopically, both sets contained the microsporidian parasite. However, the 2nd intestinal biopsy, when wasting was much more severe, contained infection in almost every small intestinal enterocyte examined. The parasite was actively developing, allowing us to detail its life cycle. The parasite is apansporoblastic, polysporous and has characteristics not previously reported in the Microsporida: (1) an electron lucent inclusion not usually seen in Microsporida is prominent and always present; (2) extremely elongated sausage-shaped nuclei occur in the proliferative phase of parasite development; (3) the polar tube development uniquely involves the production of electron dense discs, yet results in the formation of a typical spore; and (4) polar tube development occurs prior to the final division of the multi-nucleate sporont. On the basis of these characteristics, we are placing this genus in a new family, Enterocytozoonidae, n. fam.     

Mayfly bioindicator thresholds for several anthropogenic disturbances in neotropical savanna streams

Anthropogenic disturbances are widely recognized as major threats to terrestrial and aquatic biodiversity worldwide, including areas located in non-forest ecosystems. Headwater streams in the neotropical savanna are severely threatened by large-scale landscape changes that degrade local habitat characteristics and lead to biodiversity loss. The objective of our study was to evaluate Ephemeroptera assemblages as bioindicators of catchment land use and cover, local streambed and riparian vegetation conditions, and instream water quality. To do so, we sampled mayfly nymphs in 184 stream sites across a broad disturbance gradient in four hydrologic units of the Brazilian neotropical savanna. We selected seven metrics without significant co-variation with natural variability: % catchment urban, riparian vegetation condition index (RCOND), human disturbances of the stream channel and riparian zone (W1_HALL), substrate mean embeddedness (XEMBED), dissolved oxygen (mg L⁻¹), pH, and total phosphorus (mg L⁻¹). We ran threshold indicator taxa analysis (TITAN) for each disturbance metric to detect change points in mayfly genera responses (whether sensitive or tolerant) and assemblage turnover pattern. TITAN showed that 20 of the 39 genera found were robust bioindicators (based on purity and reliability values >0.95), sixteen of them being sensitive to increased disturbance. The most sensitive genera were Tricorythopsis (Leptohyphidae) and Camelobaetidius (Baetidae), showing decreased abundance to most disturbance metrics. We found a turnover pattern of mayfly genera in response to W1_HALL in a narrow variation range. For total phosphorus, the benchmark value defined in Brazilian Federal Legislation is higher than the turnover threshold of several mayfly genera. This indicates that we will lose many sensitive genera even within the limits imposed by national environmental legislation. The indicator taxa approach, based on multiple taxa rather than univariate metrics or single indicator species, demonstrates the value of quantitative ecological information for conserving and managing freshwater ecosystems globally.     

Growth and shaping of metacarpal and carpal cartilage anlagen: application of morphometry to the development of short and long bone. A study of human hand anlagen in the fetal period

A histological and morphometric analysis of human metacarpal and carpal anlagen between the 16th and 22nd embryonic weeks was carried out with the aim of studying the establishment of the respective anlage architecture. No differences in the pattern of growth were documented between the peripheral and central zones of the metacarpal epiphyses and those of the carpals. The regulation of longitudinal growth in long bone anlagen occurred in the transition zone between the epiphysis and the diaphysis (homologous to the metaphyseal growth plate cartilage in more advanced developmental stage of the bone). Comparative zonal analysis was conducted to assess the chondrocyte density, the mean chondrocyte lacunar area, the paired chondrocyte polarity in the orthogonal longitudinal and transverse planes, and the lacunar shape transformation in the metacarpal. In transition from epiphysis to diaphysis chondrocyte density decreased and mean lacunar area increased. No significant differences in the chondrocyte maturation cycle were observed between proximal/distal metacarpal epiphyses and the carpal anlagen. The number of paired chondrocyte oriented along the growth vector was significantly higher in both proximal/distal transition zones between epiphysis and diaphysis. Human metacarpals shared with experimental models (like mice and nonmammal tetrapods) an early common chondrocyte maturation cycle but with a different timing due to the slower embryonic and fetal developmental rate of human anlagen.     

A comparison of life history traits of sexual and asexual strains of the parasitoid wasp,Lysiphlebus fabarum (Braconidae: Aphidiinae)

1. This study examined biological characteristics of sexual and asexual strains of the parasitoid wasp, Lysiphlebus fabarum (Marshall) (Hymenoptera: Braconidae). 2. Strains were reared in different instar hosts (the black bean aphid, Aphis fabae Scopoli) under identical environmental conditions (21 °C, 65–75% RH, and LD 16:8 h). 3. Results showed that the second instar of the aphid is the most suitable growth stage for both strains, as the wasps that emerged from the second instar hosts were larger, more fecund, and had larger egg size. Trade‐offs between the fitness components of the parasitoid were clearer when the parasitoids were reared in suboptimal instars. 4. According to the results, sexual females emerged around 1 day earlier and lived around 0.5 day less than asexual females. Also, sexual females emerged with a lower initial egg load, although these wasps tend to have larger eggs than asexual females. Asexual females may enjoy greater longevity and higher developmental plasticity which suggests a higher degree of synchronization with pest population dynamism. 5. The results suggest that sexual wasps, in contrast to asexual wasps, invest more in egg size than in egg load. This study suggests strain‐specific adaptations of L. fabarum to different instars of the black bean aphid by which the allocation of nutritional resources to various functions differs between strains. 6. Furthermore, differences in life history traits between strains can greatly influence the population dynamics of each strain, and hence their effectiveness in suppressing pest populations.     

Regulation of endomembrane biogenesis in arabidopsis by phospatidic acid hydrolase

Coordination of membrane lipid biosynthesis is important for cell function during plant growth and development. Here we summarize our recent work on PHOSPHATIDIC ACID PHOSPHOHYDROLASE (PAH) which suggests that this enzyme is a key regulator of phosphaticylcholine (PC) biosynthesis in Arabidopsis thaliana. Disruption of PAH activity elevates phosphatidic acid (PA) levels and stimulates PC biosynthesis and biogenesis of the endoplasmic reticulum (ER). Furthermore, the activity of PHOSPHOCHOLINE CYTIDYLYLTRANSFERASE (CCT), which is the key enzyme controlling the rate of PC biosynthesis, is directly stimulated by PA and expression of a constitutively active version of CCT replicates the effects of PAH disruption. Hence PAH activity can control the abundance of PA, which in turn can modulate CCT activity to govern the rate of PC biosynthesis. Crucially it is not yet clear how PAH activity is regulated in Arabidopsis but there is evidence that PAH1 and PAH2 are both phosphorylated and further work will be required to investigate whether this is functionally significant.     

Global stability of Gause-type predator-prey systems

In this paper, we present some global stability results obtained from comparison analysis, Bendixson-Dulac criterion or limit cycle stability analysis for the general Gause-type predator-type systems.Research supported in part by a FGIA grant from the Arizona State University Research Fund AMS (MOS) subject classifications. Primary 34C05; secondary 34C25, 92A15.     

Artificial cultivation of true morels: current state,issues and perspectives

Morels (Morchella, Ascomycota), which are some of the most highly prized edible and medicinal mushrooms, are of great economic and scientific value. Morel cultivation has been a research focus worldwide for more than 100 years, and the outdoor cultivation of morels has succeeded and expanded to a large scale in China in recent years. In this study, we review the progress in recent research regarding the life cycle and reproductive systems in the genus Morchella and the current state of outdoor cultivation. Sclerotia formation and conidia production are two important phases during the life cycle. The morel species cultivated commercially in America is M. rufobrunnea based on molecular phylogenetic analysis. The species currently cultivated in China are black morels, including M. importuna, M. sextalata and M. eximia. The field cultivation of morels expanded in the majority of the provinces in China with a yield of fresh morels of 0–7620?kg per ha. The key techniques include spawn production, land preparation and spawning, the addition of exogenous nutrition, fruiting management and harvesting. The application of exogenous nutrition is the most important breakthrough in the field of morel cultivation, but the mechanism remains unclear. It was estimated that the total amount of field cultivated fresh morels was ～500 t in 2015–2016. We also discuss the potential issues remaining in the current literature and suggest directions for future studies.