Partial characterization of a nuclear proteolytic activity from fertilized sea urchin eggs

The nuclei from fertilized sea urchin eggs, obtained 80 min after fertilization, contains a neutral proteolytic activity. Optimal action on casein was observed at pH 7-8 and a Km value of 1.2 mg/ml was determined for this substrate. The proteolytic activity was stimulated 1.5 fold by the addition of 3 M urea and decreased at higher urea concentrations. NaCl and CaCl2 were inhibitory whereas MgCl2 increased the enzyme activity. Isolated histones from sea urchin sperms, and especially histones H1, H2A, H2B and H3, were degraded by the nuclear activity. A partial inhibition of histones degradation was caused by sodium bisulfite and NaCl. The proteolytic activity was found associated to the chromatin of fertilized sea urchin eggs.     

Monitoring and mechanisms of organophosphate resistance in San Jose scale,Diaspidiotus perniciosus (Hemiptera: Diaspididae)

San Jose scale, Diaspidiotus perniciosus (Comstock), is a serious pest in Chilean apple tree orchards, and a number of organophosphate insecticides were used to control them for decades. Recently, control failures with these insecticides were reported and linked to insecticide resistance development. In this study, 40 San Jose scale field populations were collected and their susceptibility to two commonly used organophosphate insecticides, that is chlorpyrifos and methidathion, was assessed. The obtained bioassay data suggest moderate levels of resistance to both insecticides when compared to a reference susceptible strain. The highest resistance ratio (RR) detected for chlorpyrifos and methidathion was 31‐fold and 11‐fold, respectively. The bioassay results suggest the occurrence of a significant cross‐resistance between both compounds. Biochemical measurements revealed a role for esterases in conferring resistance to organophosphates, but not modified acetylcholinesterase. The spatial spread and extend of insecticide resistance were also evaluated. Our result shows that no autocorrelation can be assumed, and then, insecticide resistance is caused by random factors.     

The isotopic footprint of irrigation in the western Mediterranean basin during the Bronze Age: the settlement of Terlinques,southeast Iberian Peninsula

The isotopic composition of the remains of cereals and pine has been studied, from three different chronological phases from 2140 to 1500 cal bc at the Terlinques site, southeast Iberian Peninsula. The δ¹³C values range between ?24.91 and ?21.19 ‰ (V-PDB), with an average of ?23.05 ‰ (STD = 0.69). The archaeological cereals show an average isotopic discrimination (Δ¹³C) with the past atmospheric CO₂ of 16.96 ‰, which is much greater than the average Δ¹³C of 13.89 ‰ of the rainfed Triticeae (wheat and barley) in modern times. However, considering the effect of the atmospheric CO₂ concentration, which is included in the WUEi (intrinsic water-use efficiency), this difference is even greater, 77 for archaeological samples versus 144 for present-day rainfed cereals. This could represent some of the earliest evidence of the use of irrigation techniques in Europe. Modern cereals which have been irrigated show a general Δ¹³C average of 17.17 ‰, very similar to those of the middle Holocene. However, when the WUEi is calculated, the value of 108 indicates that present-day irrigated cereals are more stressed than the archaeological samples. For comparison, we have included pine trees, since these have an extensive root development which is capable of reaching the water table. In the past, both cereals and pine present similar WUEi values (77 vs. 72), however at present only irrigated cereals show similar WUEi values to pine (108 vs. 107). This again suggests irrigation of cereals in the past. The processes of climatic degradation towards drier conditions which started in the middle Holocene could be responsible for the use of land near water sources, on riverbanks and near shallow lakes. According to the isotopic and plant macrofossil data, irrigation or water management techniques were used at the Terlinques site, located close to the Laguna de Villena, a lake which has now dried out.     

Daily growth patterns and age‐at‐recruitment of the anchoveta Engraulis ringens as indicated by a multi‐annual analysis of otolith microstructure across developmental stages

The anchoveta (Engraulis ringens ) plays a key role in the ecology of the Humboldt Current System and is of major economic importance; however, many aspects of its early life history are still poorly understood. In this study, an analysis of daily age and length patterns was carried out using the sagittal otoliths from wild larvae (0–0.2 cm standard length, L _S), pre‐recruits (3–6 cm total length, L _T), recruits (7–12 cm L _T) and young adults (12–15 cm L _T). Additionally, variability in growth and age at recruitment (A _R) were evaluated for recruits caught in northern Chile in 1973, 1982, 2009, 2010, 2012, 2013, 2014 and 2015. The age–length relationship showed four allometric patterns that were well described by Laird‐Gompertz models. The absolute growth rates at the inflexion point (G _AR) were 0.56, 0.75, 1.22 and 1.16 mm d^?1 for larvae, pre‐recruits, recruits and young adults, respectively. At the interannual scale, G _AR values were always >1 mm d^?1 (mean ± S.D . 1.37 ± 0.21 mm d^?1; range 1.12–1.64 mm d^?1), irrespective of the season of hatching (i.e. winter v. spring); additionally, in most cases, G _AR values were reached before the second month of life (mean ± S.D . 50.47 ± 9.73 days) at c. 4 cm L _T (mean ± S.D . 4.22 ± 0.29 cm). Mean A _R was < 150 days (112 ± 29 days; range 75–149 days); in contrast, estimates of A _R were higher and growth rates were lower in 1973, 1983 and 2000. These results demonstrate very fast growth and early A _R of anchoveta in northern Chile, suggesting most fish are removed by the fisheries at very early ages. An evaluation of the implications of these results on stock assessment and management of this species is highly recommended.     

Maternal separation and early stress cause long‐lasting effects on dopaminergic and endocannabinergic systems and alters dendritic morphology in the nucleus accumbens and frontal cortex in rats

A considerable amount experimental studies have shown that maternal separation (MS) is associated with adult offspring abnormal behavior and cognition disorder. Accordingly, this experimental procedure has been proposed as a predictor for alcohol and drug dependence based on the neurodevelopmental soon after birth. Endocannabinoid system (eCBs) has been implicated in reward processes, including drug abuse and dependence. MS and associated stress causes changes in the eCBs that seem to facilitate alcohol consumption. In this study, we seek to evaluate potential morphological changes in neurons of the frontal cortex (FCx) and nucleus accumbens (NAcc), in the expression of receptors and enzymes of the endocannabinoid and dopamine systems and in second messengers, such as Akt, in adult rats subjected to MS and early stress (MS + ES; 2 × 180 min daily) vs. nonseparated rats (NMS). Results showed that MS + ES induces higher D2R expression and lower D3R, FAAH, and MAGL expression compared with NMS rats. Alterations in total dendritic length were also detected and were characterized by increases in the NAcc while there were decreases in the FCx. We believe MS + ES‐induced changes in the dopaminergic and endocannabinergic systems and in the neuronal microstructure might be contributing to alcohol seeking behavior and, potential vulnerability to other drugs in rats. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 819–831, 2016