Brood size: a major factor influencing male dimorphism in the non‐pollinating fig wasp Sycobia sp.

• 1 Male polymorphisms have been described in some non‐pollinating fig wasps, as well as in other animals. The proximal basis and the maintenance of alternative male reproductive strategies are either genetic or environmental.
• 2 Here we studied male dimorphism in the non‐pollinating fig wasp Sycobia sp. We conducted experimental manipulations to study the factors influencing offspring male morph allocations and explore a possible basis for the determination and maintenance of male dimorphism in Sycobia sp.
• 3 The results showed that brood size was the major and underlying factor influencing the male morph ratio. When the brood size increases, the wingless male ratio also increases.
• 4 Also, our results indicated that there was no direct maternal control on offspring male morph allocation.
• 5 Male dimorphism in Sycobia sp. probably represents an environmentally determined conditional strategy, which responded to offspring population density at the level of the individual fig.

     

Acanthamoeba Interaction with Extracellular Matrix Glycoproteins: Biological and Biochemical Characterization and Role in Cytotoxicity and Invasiveness

ABSTRACT. Acanthamoeba are free-living amoebae that are dispersed in most environments. Occasionally, Acanthamoeba cause serious human infections, such as keratitis and encephalitis. During the infection process, amoebic adhesion to, and degradation of, host cells and their extracellular matrix (ECM) appear to be important requirements. We examined the interaction of Acanthamoeba with the ECM, and related this event to host cell destruction and tissue invasion. Pathogenic Acanthamoeba culbertsoni differentially attached on the ECM glycoproteins laminin-1, collagen-I, and fibronectin, as compared with non-pathogenic Acanthamoeba astronyxis . Binding to collagen-I and laminin-1 induced A. culbertsoni to become flattened and elongated. Because attachment on laminin-1 was higher in A. culbertsoni , laminin-1 was chosen for further analysis. A 55-kDa laminin-binding protein was identified in pathogenic amoebae, but it was not found in non-pathogenic amoebae. No differential cytotoxicity against distinct cell types was observed between A. culbertsoni incubated with or without ECM. On the other hand, binding on collagen-I or matrigel scaffolds induced a differential effect where A. culbertsoni invaded collagen-I matrices more rapidly. These results indicate that ECM recognition, as an antecedent to tissue invasion, may be a trait characteristic of pathogenic Acanthamoeba .     

First Record of the Peritrich Trichodina diaptomiBasson and Van As, 1991 (Protozoa: Ciliophora) on a South American Calanoid Notodiaptomus deitersi (Poppe, 1890) (Crustacea: Copepoda)

ABSTRACT. The ciliate Trichodina was recorded on the calanoid Notodiaptomus deitersi in a shallow, eutrophic reservoir, located in the centre‐west of Brazil. The species was confirmed as Trichodina diaptomi, a species widely distributed in Europe, Africa, Asia and Australia. It was observed moving freely over the carapace of the copepod, and using its adhesive disc. This is the first record for the species in the Americas.     

Paravahlkampfia francinae n. sp. Masquerading as an Agent of Primary Amoebic Meningoencephalitis

ABSTRACT. Paravahlkampfia francinae n. sp., a new species of the free-living amoeba genus Paravahlkampfia , designated as CDC:V595, was isolated from the cerebrospinal fluid of a patient with headache, sore throat, and vomiting, typical symptoms of primary amoebic meningoencephalitis (PAM) caused by Naegleria fowleri . The isolate grew at 33 °C, 37 °C, 40 °C, and 42 °C and destroyed mammalian cell cultures. However, it did not kill young mice upon intranasal inoculation. P. francinae does not produce flagellates and does not grow on agar plates coated with Gram-negative bacteria such as Escherichia coli , the usual food source of Paravahlkampfia ustiana , the type species of the genus. The trophozoite at light microscopy exhibited eruptive locomotion and possessed a single vesicular nucleus. Ultrastructurally, the trophozoites had numerous mitochondria with discoidal cristae but did not have a Golgi apparatus. The trophozoites differentiated into cysts after consuming most of the monolayer. The cyst had an inner well-differentiated endocyst and an outer thin, wrinkled, and wavy ectocyst with no pores. During excystation trophozoites ruptured the cyst wall and emerged from the cysts. A unique feature seen in the cysts was the presence of bacterial endosymbionts, both in the endoplasm and within the cyst wall. Full-length sequencing analysis of the 18S and 5.8S RNA genes of P. francinae showed that they were distinct from those of other Paravahlkampfia species. The patient recovered within a few days indicating that some of the previously reported cases of PAM that survived may have been due to P. francinae .     

Methylated cycloalkanes fuel a novel genus in the Porticoccaceae family (Ca. Reddybacter gen. nov)

Cycloalkanes are abundant and toxic compounds in subsurface petroleum reservoirs and their fate is important to ecosystems impacted by natural oil seeps and spills. This study focuses on the microbial metabolism of methylcyclohexane (MCH) and methylcyclopentane (MCP) in the deep Gulf of Mexico. MCH and MCP are often abundant cycloalkanes observed in petroleum and will dissolve into the water column when introduced at the seafloor via a spill or natural seep. We conducted incubations with deep Gulf of Mexico (GOM) seawater amended with MCH and MCP at four stations. Within incubations with active respiration of MCH and MCP, we found that a novel genus of bacteria belonging to the Porticoccaceae family (Candidatus Reddybacter) dominated the microbial community. Using metagenome-assembled genomes, we reconstructed the central metabolism of Candidatus Reddybacter, identifying a novel clade of the particulate hydrocarbon monooxygenase (pmo) that may play a central role in MCH and MCP metabolism. Through comparative analysis of 174 genomes, we parsed the taxonomy of the Porticoccaceae family and found evidence suggesting the acquisition of pmo and other genes related to the degradation of cyclic and branched hydrophobic compounds were likely key events in the ecology and evolution of this group of organisms.     

Variation in Copper Tolerance among Homokaryotic and Dikaryotic Mycelia of Polyporus palustris Berk. et Curt.

Investigations were made of the variation in copper toleranceamong homokaryons and dikaryons originating from one dikaryoticisolate of Polyporus palustris, as shown by their growth onnutrient agar containing copper sulphate, usually at 0.32 Mconcentration (c. 8 per cent of CuSO₄.5H₂O). Homokaryons obtainedby monobasidiospore isolation were crossed and further homokaryonsobtained in the same way. Selection for copper tolerance gavean increase in the second generation, but no further increasein the third; whilst selection for copper sensitivity gave substantialincreases in both second and third generations. It is concludedthat copper tolerance in this fungus is controlled by a numberof genes. It was found that, in this fungus, the copper toleranceof a dikaryon was substantially greater than that of eitherof its constituent homokaryons. It was also found that differentisolates of P. palustris varied very widely in copper tolerance.     

Identification of stable fly attractant compounds in vinasse,a byproduct of sugarcane–ethanol distillation

The stable fly, Stomoxys calcitrans (Diptera: Muscidae), is a worldwide pest of livestock. Recent outbreaks of stable flies in sugarcane fields in Brazil have become a serious problem for livestock producers. Larvae and pupae found inside sugarcane stems after harvesting may indicate that stable flies use these stems as potential oviposition or larval development sites. Field observations suggest that outbreaks of stable flies are associated with the vinasse and filter cake derived from biomass distillation in sugarcane ethanol production that are used as fertilizers in sugarcane fields. Adult stable flies are attracted to vinasse, which appears to present an ideal larval development site. The primary goal of the present study is to demonstrate the role of vinasse in influencing the sensory physiological and behavioural responses of stable flies, and to identify its associated volatile attractant compounds. Both laboratory and field studies showed that vinasse is extremely attractive to adult stable flies. Chemical analyses of volatiles collected revealed a wide range of carboxylic acids, alcohols, phenols and aldehydes as potential attractant compounds. These newly identified attractants could be used to develop a tool for the attractant‐baited mass trapping of stable flies in order to reduce infestations.