EFFECTS OF PARTHENOGENESIS AND GEOGRAPHIC ISOLATION ON FEMALE SEXUAL TRAITS IN A PARASITOID WASP

Population divergence in sexual traits is affected by different selection pressures, depending on the mode of reproduction. In allopatric sexual populations, aspects of sexual behavior may diverge due to sexual selection. In parthenogenetic populations, loss‐of‐function mutations in genes involved in sexual functionality may be selectively neutral or favored by selection. We assess to what extent these processes have contributed to divergence in female sexual traits in the parasitoid wasp Leptopilina clavipes in which some populations are infected with parthenogenesis‐inducing Wolbachia bacteria. We find evidence consistent with both hypotheses. Both arrhenotokous males and males derived from thelytokous strains preferred to court females from their own population. This suggests that these populations had already evolved population‐specific mating preferences when the latter became parthenogenetic. Thelytokous females did not store sperm efficiently and fertilized very few of their eggs. The nonfertility of thelytokous females was due to mutations in the wasp genome, which must be an effect of mutation accumulation under thelytoky. Divergence in female sexual traits of these two allopatric populations has thus been molded by different forces: independent male/female coevolution while both populations were still sexual, followed by female‐only evolution after one population switched to parthenogenesis.     

Geographic distribution of Ophiothela brittle stars (Echinodermata: Ophiuroidea): substrate use plasticity and implications for the silent invasion of O. mirabilis in the Atlantic

Hydrobiologia - This study aimed to address the Ophiothela species distribution worldwide, report invasive populations, and investigate their association with benthic organisms through an...     

New self-assembly nanoparticles and stealth liposomes for the delivery of zoledronic acid: a comparative study

Zoledronic acid (ZOL) is a drug whose potent anti-cancer activity is limited by its short plasma half-life and rapid uptake and accumulation within bone. We have recently proposed new delivery systems to avoid ZOL accumulation into the bone, thus improving extra-skeletal bioavailability. In this work, we have compared the technological and anti-cancer features of either ZOL-containing self-assembly PEGylated nanoparticles (NPs) or ZOL-encapsulating PEGylated liposomes (LIPO-ZOL). ZOL-containing NPs showed superior technological characteristics in terms of mean diameter, size distribution, and ZOL encapsulation efficiency, compared to LIPO-ZOL. Moreover, the anti-cancer activity of NPs in nude mice xenografted with prostate cancer PC3 cells was higher than that one induced by LIPO-ZOL. In addition, NPs induced the complete remission of tumour xenografts and an increase of survival time higher than that one observed with LIPO-ZOL. It has also to be considered that PC3 tumour xenografts were almost completely resistant to the anti-cancer effects induced by free ZOL. Both nanotechnological products did not induce toxic effects not affecting the mice weight nor inducing deaths. Moreover, the histological examination of some vital organs such as liver, kidney and spleen did not find any changes in terms of necrotic effects or modifications in the inflammatory infiltrate. On the other hand, NPs but not LIPO-ZOL caused a statistically significant reduction of the tumour associated macrophages (TAM) in tumour xenografts. This effect was paralleled by a significant increase of both necrotic and apoptotic indexes. The effects of the NPs were also higher in terms of neo-angiogenesis inhibition. These results suggest the future preclinical development of ZOL-encapsulating NPs in the treatment of human cancer.     

Isoform specific function of calpain 2 in regulating membrane protrusion

Previous studies have demonstrated a role for calpains in cell migration through their capacity to regulate focal adhesion dynamics and rear retraction. In this study, we provide evidence that calpains also modulate membrane protrusion activity in fibroblasts. We find that an immortalized Capn4(-/-) fibroblast line displays an altered morphology, characterized by numerous thin membrane projections and increased transient membrane activity. Furthermore, we show that protrusion kinetics of lamellipodia at the leading edge are improperly regulated in Capn4(-/-) cells, leading to impaired net forward lamellipodial extension. To address the isoform specific functions of calpain 1 and calpain 2 during cell protrusion, we stably introduced small interfering RNAs (siRNAs) targeting each isoform into a fibroblast cell line. Despite a loss in calpain 1 activity, calpain 1 knockdown cells show normal morphology and membrane protrusion dynamics. However, cells in which calpain 2 is knocked down are characterized by a protrusive morphology, increased transient membrane activity and altered protrusion kinetics, similar to the Capn4(-/-) fibroblasts. Additionally, we find that calpain 2, but not calpain 1, is required for proteolysis of the cytoskeletal and focal adhesion proteins FAK, paxillin, spectrin, and talin. Together, our findings support a novel role for calpain 2 in limiting membrane protrusions and in regulating lamellipodial dynamics at the leading edge of migrating cells.     

Analysis of X-chromosome inactivation and presumptive expression of the Wiskott-Aldrich syndrome (WAS) gene in hematopoietic cell lineages of a thrombocytopenic carrier female of WAS

Summary We report on a thrombocytopenic female belonging to a pedigree with the Wiskott-Aldrich syndrome (WAS). Restriction fragment length polymorphism (RFLP) analysis with probe M27, closely linked to the WAS gene, demonstrated that she is a carrier of WAS. Both small-sized and normal-sized platelets were present, suggesting that, unlike the vast majority of WAS carriers, she does not manifest nonrandom X-chromosome inactivation in the thrombopoietic cell lineage. Study of X-chromosome inactivation by means of RFLP and methylation analysis demonstrated that the pattern of X-chromosome inactivation was nonrandom in T lymphocytes, but random in granulocytes. While this is the first complete report on the occurrence of thrombocytopenia in a carrier female of WAS as the result of atypical lyonization, it also suggests that expression of the WAS gene occurs at (or extends up to) a later stage than the multipotent stem cell along the hematopoietic differentiation pathway.     

Circadian-related heteromerization of adrenergic and dopamine D₄ receptors modulates melatonin synthesis and release in the pineal gland

The role of the pineal gland is to translate the rhythmic cycles of night and day encoded by the retina into hormonal signals that are transmitted to the rest of the neuronal system in the form of serotonin and melatonin synthesis and release. Here we describe that the production of both melatonin and serotonin by the pineal gland is regulated by a circadian-related heteromerization of adrenergic and dopamine D₄ receptors. Through α_{1 B}-D₄ and β₁-D₄ receptor heteromers dopamine inhibits adrenergic receptor signaling and blocks the synthesis of melatonin induced by adrenergic receptor ligands. This inhibition was not observed at hours of the day when D₄ was not expressed. These data provide a new perspective on dopamine function and constitute the first example of a circadian-controlled receptor heteromer. The unanticipated heteromerization between adrenergic and dopamine D₄ receptors provides a feedback mechanism for the neuronal hormone system in the form of dopamine to control circadian inputs.     

Exploring the biocontrol potential of fungal endophytes from an Andean Colombian Paramo ecosystem

We studied the diversity and biocontrol potential of 100 fungal endophytes isolated from Espeletia spp., endemic plant species from the Paramo in the Andean mountain range. Our sample was genotypically highly diverse at all ITS similarity levels. The antagonistic properties of these isolates were tested against common crop pathogens in Colombia, including Pectobacterium carotovorum, Ralstonia solanacearum, Pseudomonas syringae, Xanthomonas campestris, Rhizoctonia solani, Botrytis cinerea, Fusarium oxysporum, and Phytophthora infestans. All endophytic isolates were able to significantly inhibit the growth of at least one of the plant pathogens tested (P?<?0.05). Three main types of endophyte/pathogen interactions were observed. However, only those endophytes that produced an evident inhibition halo were further studied using their crude extracts to confirm that the inhibitory effect was due to the production of endophytic bioactive metabolites. From these experiments, nine promising isolates were selected for co-inoculation tests with R. solani in tomato plants. The isolates identified as Aureobasidium pullulans and Paraconiothyrium sporulosum not only protected the plants against this pathogen but also allowed them to exhibit similar growth and development as the uninoculated control. This work explores new alternatives for disease management without the application of chemical pesticides.     

The effect of light levels on daily patterns of chlorophyll fluorescence and organic acid accumulation in the tropical CAM treeClusia hilariana

Sandy plains are characteristic of the coastal region of Brazil. We investigated the diel patterns of changes in organic acid levels, leaf conductance and chlorophylla fluorescence for sun-exposed and shaded plants ofClusia hilariana, one of the dominant woody species in the sandy coastal plains of northern Rio de Janeiro state. Both exposed and shaded plants showed a typical CAM pattern with considerable diel oscillations in organic acid levels. The degradation of both malic and citric acids during the midday stomatal closure period could lead to potential CO₂ fixation rates of 28 mol m^-2 s^-1 in exposed leaves. Moreover, exposed leaves exhibited large increases in total non-photochemical quenching (q_N) accompanied by a substantial decrease in effective quantum yield during the course of the day. However, these potential high rates of CO₂ fixation and the increases inqn of exposed plants were not enough to maintain the primary electron acceptor of photosystem II (q_A) in a low reduction state, similar to that of shaded plants. As a result, there was a moderate increase in the reduction state of q_A throughout the day. Most of the decline in photochemical efficiency of exposed leaves ofC. hilariana was reversible, as evidenced by the high levels of pre-dawn potential quantum yields (F_v/F_m) and their rapid recovery after sunset. However, the depletion of the organic acid pool in the afternoon resulted in an accentuated subsequent drop in F_v/F_m, suggesting that prolonged periods of water stress accompanied by high irradiance levels may expose plants ofC. hilariana in unprotected habitats to the danger of photoinhibition.     

Description of Thecavermiculatus andinus n.sp. (Meloidoderidae), a Round Cystoid Nematode from the Andes Mountains of Peru

Thecavermiculatus andinus n.sp. is described and illustrated from Oxalis tuberosa originally collected in the vicinity of Lake Titicaca high in the Andes mountains of southern Peru. This new species differs markedly front the other two species in the genus, especially in having a much greater female vulval-anal distance and annules with lined punctation on most of the female body with a lacelike pattern restricted to the posterior portion, particularly at the vulva and anus which do not protrude. Females are essentially spherical with protruding neck, white to yellowish in color, and can easily be mistaken for potato cyst nematodes. Among the dozen or more known weed and crop host plants are potato and eggplant. In order to accommodate this new species, the genus Thecavermieulatus is emended. A key to the species of this genus is presented.