alpha and beta spectrin distribution during the differentiation of pyriform cells in follicles of lizard Podarcis sicula

Using alpha and beta spectrin mammalian antibodies on Western blotting, we demonstrated that lizard ovarian follicles contain two isoforms of alpha spectrin, Mr 94 and 134 kDa, and a 230 kDa beta spectrin, and that their pattern modifies in relation to pyriform cell differentiation. In fact, a positive immunoreaction is firstly evident within follicular epithelium of previtellogenic follicles when small cells differentiate into pyriform cells via intermediate cells. Later on, immunostain is present in pyriform cells and in the oocyte cortex that previously appears unstained. It is noteworthy that immunostain is also present on small cells located in contact with the oocyte membrane, but not on those located under the basal lamina and among pyriform cells, not engaged in pyriform cell differentiation. During the subsequent stages of previtellogenic phase, spectrin immunostain over the follicular epithelium and in the oocyte cortex does not change. By contrast, in vitellogenic follicles, when the follicular epithelium is constituted only by small cells, immunostain is evident at the level of the oocyte cortex and the cytoplasm of regressing pyriform cells. The present data strongly suggest that the alpha and beta spectrin pattern put in evidence during the different phases of lizard oocyte growth is related to the differentiation of small into pyriform cells, where such protein may guarantee a relationship between surface glycoproteins (Andreuccetti et al., 2001: Anat Rec 263:1-9), and the cytoskeleton distribution (Maurizii et al., 2000: Raf Mol Reprod Dev 57:159-166). Furthermore, the distribution of spectrin mRNA, similar to that observed for the protein, demonstrates that spectrin, once synthesized within pyriform cells, is transferred through intercellular bridges in the oocyte cortex, thus confirming that pyriform cells are nurse that significantly are involved in the oocyte growth. Finally, the present data demonstrate that alpha spectrin of lizard ovarian follicles has Mr quite different from those so far reported and may constitute a new group of isoforms. This important result will be the focus of future experiments. Mol. Reprod. Dev. 67: 101-107, 2004.     

Science and Engineering Ph.D. Students’ Career Outcomes,by Gender

We examine differences in the careers of men and women Ph.D.s from two major European universities. Having performed regression analysis, we find that women are more likely than men to be employed in public administration when the alternatives are either academia or industry. Between the latter two alternatives, women are more likely to be employed in academia. These gender differences persist after accounting for Ph.D.s’ and their supervisors’ characteristics. Gender gaps are smaller for Ph.D.s with large research outputs and for those who conducted applied research. Restricting the analysis to Ph.D.s who pursued postdoc training, women are less likely than men to be employed in highly ranked universities, even after controlling for their research outputs. Finally, we find gender differences in Ph.D.s’ appointment to professorship, which are explained by the Ph.D.s’ publication output and the quality of their postdoc training.     

Human Protein Cluster Analysis Using Amino Acid Frequencies

The paper focuses on the development of a software tool for protein clustering according to their amino acid content. All known human proteins were clustered according to the relative frequencies of their amino acids starting from the UniProtKB/Swiss-Prot reference database and making use of hierarchical cluster analysis. Results were compared to those based on sequence similarities. Results: Proteins display different clustering patterns according to type. Many extracellular proteins with highly specific and repetitive sequences (keratins, collagens etc.) cluster clearly confirming the accuracy of the clustering method. In our case clustering by sequence and amino acid content overlaps. Proteins with a more complex structure with multiple domains (catalytic, extracellular, transmembrane etc.), even if classified very similar according to sequence similarity and function (aquaporins, cadherins, steroid 5-alpha reductase etc.) showed different clustering according to amino acid content. Availability of essential amino acids according to local conditions (starvation, low or high oxygen, cell cycle phase etc.) may be a limiting factor in protein synthesis, whatever the mRNA level. This type of protein clustering may therefore prove a valuable tool in identifying so far unknown metabolic connections and constraints.     

Little evidence for release from herbivores as a driver of plant invasiveness from a multi‐species herbivore‐removal experiment

Enemy release is frequently posed as a main driver of invasiveness of alien species. However, an experimental multi‐species test examining performance and herbivory of invasive alien, non‐invasive alien and native plant species in the presence and absence of natural enemies is lacking. In a common garden experiment in Switzerland, we manipulated exposure of seven alien invasive, eight alien non‐invasive and fourteen native species from six taxonomic groups to natural enemies (invertebrate herbivores), by applying a pesticide treatment under two different nutrient levels. We assessed biomass production, herbivore damage and the major herbivore taxa on plants. Across all species, plants gained significantly greater biomass under pesticide treatment. However, invasive, non‐invasive and native species did not differ in their biomass response to pesticide treatment at either nutrient level. The proportion of leaves damaged on invasive species was significantly lower compared to native species, but not when compared to non‐invasive species. However, the difference was lost when plant size was accounted for. There were no differences between invasive, non‐invasive and native species in herbivore abundance. Our study offers little support for invertebrate herbivore release as a driver of plant invasiveness, but suggests that future enemy release studies should account for differences in plant size among species.     

Uno studio citofotometrico delle proteine durante la mitosi nel meristema radicale di Allium cepa L.

Abstract

A cytophotometric study of proteins during mitosis in root tip meristematic cells of «Allium cepa L.». — Spectrophotometric analyses of the amount of Fast-green stainable proteins at different pH values (8,1; 6; 4; 2) have been accomplished in Allium cepa root tip meristematic cells during the four phases of mitosis. The results seem to indicate that: a) the highest absorption is detectable in correspondence of metaphase at each of the four pH values; b) the transition from prophase to metaphase is characterized by an increase of both proteins reacting at pH 8,1 (histones) and between pH 6 and pH 8,1 (neutral proteins); c) the transition from metaphase to anaphase is characterized by a loss of histones and of proteins reacting between pH 4 and pH 6 (acid proteins); d) the transition from anaphase to telophase is characterized by a loss of neutral proteins. The data are discussed in relation to the problem of chromosome coiling.     

Aerobic Biodegradation of N-Nitrosodimethylamine by the Propanotroph Rhodococcus ruber ENV425

The propanotroph Rhodococcus ruber ENV425 was observed to rapidly biodegrade N-nitrosodimethylamine (NDMA) after growth on propane, tryptic soy broth, or glucose. The key degradation intermediates were methylamine, nitric oxide, nitrite, nitrate, and formate. Small quantities of formaldehyde and dimethylamine were also detected. A denitrosation reaction, initiated by hydrogen atom abstraction from one of the two methyl groups, is hypothesized to result in the formation of n-methylformaldimine and nitric oxide, the former of which decomposes in water to methylamine and formaldehyde and the latter of which is then oxidized further to nitrite and then nitrate. Although the strain mineralized more than 60% of the carbon in [¹⁴C]NDMA to ¹⁴CO₂, growth of strain ENV425 on NDMA as a sole carbon and energy source could not be confirmed. The bacterium was capable of utilizing NDMA, as well as the degradation intermediates methylamine and nitrate, as sources of nitrogen during growth on propane. In addition, ENV425 reduced environmentally relevant microgram/liter concentrations of NDMA to <2 ng/liter in batch cultures, suggesting that the bacterium may have applications for groundwater remediation.N-Nitrosodimethylamine (NDMA) is a potent carcinogen that has recently been detected in groundwater, wastewater, and drinking water (1, 2, 17, 18). It forms as a disinfection byproduct in wastewater and drinking water treated with chloramine and other disinfectants (17, 18, 43). NDMA has also been found to be present in aquifers at several military sites that have used 1,1-dimethylhydrazine, a component of liquid rocket propellant that contained NDMA as an impurity (6, 9). Although there is presently no federal maximum contaminant level for NDMA in drinking water, a risk assessment conducted by the U.S. Environmental Protection Agency suggested that concentrations as low as 0.7 ng/liter can increase lifetime cancer risk by 1 × 10⁻⁶ (34). In addition, California currently has a 10 ng/liter notification level for NDMA concentrations in drinking water and has recently recommended an even lower public health goal of 3 ng/liter (3, 20). Thus, the presence of even trace concentrations of this chemical in drinking water represents a potential public health concern.The rates and extents of NDMA biodegradation in natural environments, including surface water, sludges, and soils, are highly variable. In some studies, the compound has been reported to be recalcitrant or only partially biodegraded (16, 30, 31); in others, fairly rapid and extensive biodegradation has been previously observed (2, 13, 22, 40). Few studies have been conducted to examine NDMA biodegradation in groundwater. However, the persistence of NDMA derived originally from 1,1-dimethylhydrazine-based rocket fuel over decades in some groundwater aquifers (e.g., Rocky Mountain Arsenal, CO; former Air Force Plant PJKS, CO; and Aerojet Superfund Site, CA) suggests that this molecule can be very recalcitrant (8, 9, 35). At sites where biodegradation has been observed, the organisms responsible and the microbial degradation pathways are largely unknown.The metabolism of NDMA and other nitrosamines by mammals has received extensive study. NDMA requires metabolic activation to the methyldiazonium ion (a strong alkylating agent) to exert its genotoxic effects (1, 19, 34). This activation reaction is catalyzed by specific isozymes of the cytochrome P-450-dependent mixed-function oxidase system and proceeds through an initial α-hydroxylation reaction. Alternately, NDMA can be oxidized by the P-450 system via a denitrosation route, which does not result in the formation of a highly carcinogenic intermediate (11, 28, 37).The bacterial transformation of NDMA has not been studied in significant detail. Several bacteria expressing broad-specificity monooxygenase enzymes have been reported to degrade NDMA via cometabolism. These include the propanotrophs Rhodococcus sp. strain RHA1 (25, 26) and Rhodococcus ruber ENV425 (29) as well as Mycobacterium vaccae JOB5 (25), the methanotroph Methylosinus trichosporium OB3b (42), and the toluene oxidizer Pseudomonas mendocina KR1 (7). We recently characterized the pathway of NDMA transformation used by P. mendocina KR1, a bacterium that utilizes the enzyme toluene-4-monooxygenase (T4MO) to cometabolically degrade NDMA and other anthropogenic pollutants (7, 38). The pathway of NDMA transformation by KR1 differs from the two pathways described for mammals. A majority of the NDMA metabolized by T4MO in this strain is oxidized to N-nitrodimethylamine (NTDMA) and then further to N-nitromethylamine (NTMA), which accumulates as a terminal product (7).In this report, we describe the pathway used by the propanotroph R. ruber ENV425 to catabolize NDMA. This strain was originally isolated from turf soil, where propane was used as the sole carbon source, and was previously reported to oxidize methyl tertiary-butyl ether and other gasoline oxygenates (27). Our data show that the pathway of NDMA degradation mediated by strain ENV425 differs from that mediated by P. mendocina KR1. Rather, the pathway used for transformation of NDMA by ENV425 appears to be similar to the denitrosation pathway catalyzed by various P-450 isozymes in mammals, resulting in the production of nitric oxide (NO), nitrite, nitrate, formaldehyde, formate, and methylamine (MA) (11, 12, 28, 39). A significant fraction of the carbon in the NDMA molecule was released as CO₂ by strain ENV425, although growth on NDMA could not be confirmed. However, the bacterium was observed to utilize NDMA as well as the NDMA-degradation intermediates MA and nitrate as sources of nitrogen during growth on propane as a sole carbon and energy source.     

Animal resources and subsistence strategies

Several faunal assemblages excavated in deposits of different antiquity (from Lower Paleolithic to Bronze Age), located in Northern, Central and Southern Italy, were studied from the archeozoological and taphonomic point of view. Data obtained by different Authors allow reconstruction of subsistence strategies adopted by prehistoric humans in these areas and through time, in particular as far as the exploitation of animal resources is concerned. The following assemblages were considered: Isernia La Pineta (Molise; Lower Paleolithic), Grotta Breuil (Latium; Middle Paleolithic), Grotta della Ghiacciaia (Verona; Middle Paleolithic), Riparo di Fumane and Riparo Tagliente (Verona; Middle and Upper Paleolithic), Riparo Mochi (Liguria; Upper Paleolithic), Grotta della Continenza (L'Aquila; Upper Paleolithic and Mesolithic), Grotta dell'Edera (Trieste; Mesolithic and Neolithic), Grotta della Cala at Marina di Camerota (Salerno; Eneolithic), Contraguda (Sassari; Neolithic), Castellaro Lagusello (Mantova; Bronze Age). Exploitation of the vegetal resources has been analyzed in the Neolithic sites of Colle Santo Stefano (Fucino), Settefonti (L'Aquila) and Catignano (Pescara).