Magnetic particles associated with the lateral line of the European eel Anguilla anguilla

Magnetization measurements of the European eel Anguilla anguilla demonstrated the presence of magnetic material concentrated in the region of the mandibular canals of the lateral line system. The data suggest that the material is magnetite, has a size suitable for magnetoreception and is of biogenic origin. The presence of magnetic particles in the lateral line system is discussed in relation to their possible role in allowing the fish to orientate with respect to the geomagnetic field during their extensive oceanic spawning migrations.     

Deciphering earth mound origins in central Brazil

Mound fields are a common landscape throughout the world and much of the evidence for their origin has been of a circumstantial nature. It has been hypothesized that earth mounds emerge over grasslands by termite activity; alternatively, they might be formed after erosion. We tested whether a mound field in central Brazil was generated by termite activity or erosion. We used soil organic matter isotopic composition, soil chemical, physical and floristic composition to determine the origin of a mound field. If the mounds emerged by termite activity in an established grassland the soil organic matter below the mound should have the isotopic signature of C₄ dominated grassland, which contrasts with savanna C₃ + C₄ signature. Additionally, soil traits should resemble those of the grassland. All markers indicate that the mounds were formed by erosion. The soil isotopic composition, chemical traits and texture below the mound resembled those of the savanna and not those of the grassland. Moreover, most of the species present in the mound were typical of savanna. Concrete evidence is provided that mound fields in the studied area were produced by erosion of a savanna ecosystem and not termite activity. The use of the techniques applied here would improve the assessments of whether analogous landscapes are of a biogenic nature or not.     

Microbial production and characterization of superparamagnetic magnetite nanoparticles by Shewanella sp. HN-41

A facultative dissimilatory metal-reducing bacterium, Shewanella sp. strain HN-41, was used to produce magnetite nanoparticles from a precursor, poorly crystalline ironoxyhydroxide akaganeite (beta-FeOOH), by reducing Fe(III). The diameter of the biogenic magnetite nanoparticles ranged from 26 nm to 38 nm, characterized by dynamic light scattering spectrophotometry. The magnetite nanoparticles consisted of mostly uniformly shaped spheres, which were identified by electron microscopy. The magnetometry revealed the superparamagnetic property of the magnetic nanoparticles. The atomic structure of the biogenic magnetite, which was determined by extended X-ray absorption fine structure spectroscopic analysis, showed similar atomic structural parameters, such as atomic distances and coordinations, to typical magnetite mineral.     

Analysis of magnetic material in the human heart, spleen and liver

Isothermal remanent magnetization (IRM) acquisition and alternating field (A.F.) demagnetization analyses were performed on human heart, spleen and liver samples resected from cadavers. The magnetic properties of the samples were measured both at 77K and at 273K. A.F. demagnetization was performed at 273K. Results from the analyses of the tissue indicate the presence of ferromagnetic, fine-grained, magnetically interacting particles which, due primarily to magnetic properties, are thought to be magnetite and/or maghemite. The presence of superparamagnetic particles can be inferred from the increase in saturation IRM values when measured at 77K compared with measurements at 273K and the decay of remanent magnetization upon warming from 77K. The concentration of magnetic material (assuming it is magnetite or maghemite) in the samples varies from 13.7 ng g-1 to 343 ng g-1, with the heart tissue generally having the highest concentration. The presence of magnetic material in these organs may have implications for the function of biogenic magnetite in the human body.     

Nests of subterranean fungus-growing termites (Isoptera, Macrotermitinae) as nutrient patches for grasses in savannah ecosystems

Savannah are ecosystems in which mineral nitrogen is considered as a limiting factor for plant productivity. They are heterogeneous and spatially structured in patches, or islands, where mineral nitrogen content is concentrated. Among the soil macrofauna, termites of the Macrotermitinae subfamily are major determinants of soil heterogeneity through the biogenic underground nest structures (fungus‐comb chambers) they produce. To study the role of the heterogeneity created by termites on Pennisetum pedicellatum, an herbaceous grass species was grown in greenhouse. This was carried out using an homogeneous soil poor in mineral nitrogen, and an heterogeneous soil with patch, made of (i) Ancistrotermes cavithorax fungus‐comb chamber wall and (ii) soil with the same mineral nitrogen content as the termite handled soil. Plants exhibited a better growth on patch of termite‐modified soil whereas no significant differences were shown with the supply of mineral nitrogen. The presence of fungus‐comb chamber wall material resulted in an increase of fine root biomass and root/shoot ratio. We conclude that termites, through their building activities, may create nutrient patches available to grasses. Concurrently, our data illustrate that the higher mineral nitrogen content in termite‐built structures is not the only factor responsible for plant growth.     

异化铁还原细菌LQ25还原重金属Cr (VI)的特性研究

[背景] 异化铁还原细菌能够在还原Fe （III）的同时将毒性较大的Cr （VI）还原成毒性较小的Cr （III）,解决铬污染的问题。[目的] 基于丁酸梭菌（Clostridium butyricum） LQ25异化铁还原过程制备生物磁铁矿,开展异化铁还原细菌还原Cr （VI）的特性研究。[方法] 构建以氢氧化铁为电子受体和葡萄糖为电子供体的异化铁培养体系。菌株LQ25培养结束时制备生物磁铁矿。设置不同初始Cr （VI）浓度（5、10、15、25和30 mg/L）,分别测定菌株LQ25对Cr （VI）还原效率以及生物磁铁矿对Cr （VI）的还原效率。[结果] 菌株LQ25在设置的Cr （VI）浓度范围内都能良好生长。当Cr （VI）浓度为15 mg/L时,在异化铁培养条件下,菌株LQ25对Cr （VI）的还原率为63.45%±5.13%,生物磁铁矿对Cr （VI）的还原率为87.73%±9.12%,相比菌株还原Cr （VI）的效率提高38%。pH变化能影响生物磁铁矿对Cr （VI）的还原率,当pH 2.0时,生物磁铁矿对Cr （VI）的还原率最高,几乎达到100%。电子显微镜观察发现生物磁铁矿表面有许多孔隙,X-射线衍射图谱显示生物磁铁矿中Fe （II）的存在形式是Fe （OH）₂。[结论] 基于异化铁还原细菌制备生物磁铁矿可用于还原Cr （VI）,这是一种有效去除Cr （VI）的途径。     

Iron-rich particles in European eel (Anguilla anguilla L.)

Magnetic material in the European eel (Anguilla anguilla L.) was investigated by a combination of magnetic susceptibility measurements, energy dispersive X-ray fluorescence analysis and transmission electron microscopy. It was shown that the magnetic material is associated with iron. The main part of the iron is present in the form of iron-rich particles with irregular shapes about 100-3000 A large. The structures of magnetite (Fe3O4), hematite (alpha-Fe2O3) and alpha-iron (bcc structure) were identified. The particles are composed of more than one of these phases with magnetite being a minority phase when present. The iron-rich particles found in the eel are different from the materials reported for bacteria or bees.     

Isolation by distance,not rivers,control the distribution of termite species in the Amazonian rain forest

The spatial distribution of species is affected by dispersal barriers, local environmental conditions and climate. However, the effect of species dispersal and their adaptation to the environment across geographic scales is poorly understood. To investigate the distribution of species from local to broad geographic scales, we sampled termites in 198 transects distributed in 13 sampling grids in the Brazilian Amazonian forest. The sampling grids encompassed an area of 271 500 km² and included the five major biogeographic regions delimited by Amazonian rivers. Environmental data for each transect were obtained from local measurements and remote sensing. Similar to previous studies, termite species composition at the local scale was mostly associated with measures of soil texture and chemistry. In contrast, termite species composition at broad geographic scales was associated with soil nutrients, and the geographic position of the transects. Between 17 and 30% of the variance in termite species composition could be attributed exclusively to the geographic position of the transects, but could not be attributed to measured environmental variables or the presence of major rivers. Isolation by distance may have strong effects on termite species composition due to historic processes and the spatially structured environments along distinct geological formations of Amazonia. However, in contrast to many taxa in Amazonia, there is no evidence that major rivers are important barriers to termite dispersal.     

Extended disease resistance emerging from the faecal nest of a subterranean termite

Social insects nesting in soil environments are in constant contact with entomopathogens but have evolved a range of defence mechanisms, resulting in both individual and social immunity that reduce the chance for epizootics in the colony, as in the case of subterranean termites. Coptotermes formosanus uses its faeces as building material for its nest structure that result into a ‘carton material’, and here, we report that the faecal nest supports the growth of Actinobacteria which provide another level of protection to the social group against entomopathogens. A Streptomyces species with in vivo antimicrobial activity against fungal entomopathogens was isolated from the nest material of multiple termite colonies. Termite groups were exposed to Metarhizium anisopliae, a fungal entomopathogen, during their foraging activity and the presence of Streptomyces within the nest structure provided a significant survival benefit to the termites. Therefore, this report describes a non-nutritional exosymbiosis in a termite, in the form of a defensive mutualism which has emerged from the use of faecal material in the nesting structure of Coptotermes. The association with an Actinobacteria community in the termite faecal material provides an extended disease resistance to the termite group as another level of defence, in addition to their individual and social immunity.     

Shell structure in Difflugia Lobostoma observed by scanning and transmission electron microscopy

Observations by scanning and transmission electron microscopy provide information about shells of Difflugia lobostoma which suggests a complex activity in shell construction. As observed by scanning microscopy, the shell consists of a single layer of sand grains which are organized into rosettes. The sand grains of the rosettes are different in size from those of flat areas between rosettes suggesting that the organism sorts these stones and places them according to size. Hydrofluoric acid treatment dissolves the sand but leaves a web of cement material intact. Examination of such acid treated specimens by transmission microscopy shows structure in the cement material of the shell, and granules of similar structure in the cell body. The rosette pattern observed differs from shell patterns in other species of Difflugia, and this suggests that shell structure may be species specific.     

Direct and Fe(II)-Mediated Reduction of Technetium by Fe(III)-Reducing Bacteria

The dissimilatory Fe(III)-reducing bacterium Geobacter sulfurreducens reduced and precipitated Tc(VII) by two mechanisms. Washed cell suspensions coupled the oxidation of hydrogen to enzymatic reduction of Tc(VII) to Tc(IV), leading to the precipitation of TcO₂ at the periphery of the cell. An indirect, Fe(II)-mediated mechanism was also identified. Acetate, although not utilized efficiently as an electron donor for direct cell-mediated reduction of technetium, supported the reduction of Fe(III), and the Fe(II) formed was able to transfer electrons abiotically to Tc(VII). Tc(VII) reduction was comparatively inefficient via this indirect mechanism when soluble Fe(III) citrate was supplied to the cultures but was enhanced in the presence of solid Fe(III) oxide. The rate of Tc(VII) reduction was optimal, however, when Fe(III) oxide reduction was stimulated by the addition of the humic analog and electron shuttle anthaquinone-2,6-disulfonate, leading to the rapid formation of the Fe(II)-bearing mineral magnetite. Under these conditions, Tc(VII) was reduced and precipitated abiotically on the nanocrystals of biogenic magnetite as TcO₂ and was removed from solution to concentrations below the limit of detection by scintillation counting. Cultures of Fe(III)-reducing bacteria enriched from radionuclide-contaminated sediment using Fe(III) oxide as an electron acceptor in the presence of 25 μM Tc(VII) contained a single Geobacter sp. detected by 16S ribosomal DNA analysis and were also able to reduce and precipitate the radionuclide via biogenic magnetite. Fe(III) reduction was stimulated in aquifer material, resulting in the formation of Fe(II)-containing minerals that were able to reduce and precipitate Tc(VII). These results suggest that Fe(III)-reducing bacteria may play an important role in immobilizing technetium in sediments via direct and indirect mechanisms.     

Can the presence of structural phosphorus help to discriminate between abiogenic and biogenic magnetites?

The influence of phosphate on the competitive formation of magnetite and lepidocrocite and the properties of magnetite prepared from mixtures of Fe(II) and Fe(III) salts were studied. Products were prepared at 90 °C and pH 12.5 (series 1), 50 °C and pH 7 (series 2) and 20 °C and pH 8 (series 3). The P/Fe atomic ratio in the initial solution ranged from 0 to 3% and the pH was kept at the desired value with NaOH or KOH. Air was used as oxidant in series 2 and 3. All products, which were characterized by X-ray diffraction, transmission electron microscopy, chemical analysis and IR spectroscopy, contained a phase intermediate between magnetite and maghemite (referred to as magnetite in this paper). The products of series 1 consisted only of magnetite at all P/Fe ratios, whereas both magnetite and lepidocrocite formed in series 2 and 3 above a certain P/Fe ratio. On increasing the P/Fe ratio in the initial solution, the magnetite crystals became smaller and more oxidized (i.e. closer to maghemite) and the lepidocrocite/magnetite ratio increased. The P associated with magnetite was partly in the form of occluded P, i.e. non-surface-adsorbed phosphate. IR spectra suggested this P to be structural and occurring as low-symmetry PO₄ units. Because abiogenic magnetites produced in various environments incorporate structural P but some well-characterized biogenic magnetites seem to contain no P or be formed in P-poor environments, we hypothesize that natural magnetites containing occluded P are unlikely to be biogenic. However, more studies are needed to discard the presence of P in biogenic magnetites.     

Insights into a hydration regulating system in Cupressus pollen grains

Background and Aims

Hydration, rupture and exine opening due to the sudden and large expansion of intine are typical of taxoid-type pollen grains. A hemispheric outgrowth external to the exine was observed on Cupressus and Juniperus pollen grains before the intine swelling and exine release. However, the actual existence of this permanent or temporary structure and its precise role in pollen hydration is still being debated. The aim of this paper is to collect information on the actual presence of this peculiar outgrowth on the surface of the Cupressus pollen grain, its structure, composition and function.

Methods

Pollen grains of several Cupressus species were observed using various techniques and methodologies, under light and fluorescence microscopy, phase-contrast microscopy, confocal microscopy, scanning electron microscopy, and an environmental scanning electron microscope. Observations were also performed on other species with taxoid-type pollen grains.

Key Results

A temporary structure located just above the pore was observed on Cupressus pollen grains, as well as on other taxoid-type pollens. It is hemispheric, layered, and consists of polysaccharides and proteins. The latter are confined to its inner part. Its presence seems to regulate the entrance of water into the grains at the beginning of pollen hydration.

Conclusions

The presence of a temporary structure over the pore of taxoid-type pollen grains was confirmed and its structure was resolved using several stains and observation techniques. This structure plays a role in the first phases of pollen hydration.     

Analysis of Magnetosome Chains in Magnetotactic Bacteria by Magnetic Measurements and Automated Image Analysis of Electron Micrographs

Magnetotactic bacteria (MTB) align along the Earth''s magnetic field by the activity of intracellular magnetosomes, which are membrane-enveloped magnetite or greigite particles that are assembled into well-ordered chains. Formation of magnetosome chains was found to be controlled by a set of specific proteins in Magnetospirillum gryphiswaldense and other MTB. However, the contribution of abiotic factors on magnetosome chain assembly has not been fully explored. Here, we first analyzed the effect of growth conditions on magnetosome chain formation in M. gryphiswaldense by electron microscopy. Whereas higher temperatures (30 to 35°C) and high oxygen concentrations caused increasingly disordered chains and smaller magnetite crystals, growth at 20°C and anoxic conditions resulted in long chains with mature cuboctahedron-shaped crystals. In order to analyze the magnetosome chain in electron microscopy data sets in a more quantitative and unbiased manner, we developed a computerized image analysis algorithm. The collected data comprised the cell dimensions and particle size and number as well as the intracellular position and extension of the magnetosome chain. The chain analysis program (CHAP) was used to evaluate the effects of the genetic and growth conditions on magnetosome chain formation. This was compared and correlated to data obtained from bulk magnetic measurements of wild-type (WT) and mutant cells displaying different chain configurations. These techniques were used to differentiate mutants due to magnetosome chain defects on a bulk scale.     

Evolution of termite functional diversity: analysis and synthesis of local ecological and regional influences on local species richness

Aim To (1) describe termite functional diversity patterns across five tropical regions using local species richness sampling of standardized areas of habitat; (2) assess the relative importance of environmental factors operating at different spatial and temporal scales in influencing variation in species representation within feeding groups and functional taxonomic groups across the tropics; (3) achieve a synthesis to explain the observed patterns of convergence and divergence in termite functional diversity that draws on termite ecological and biogeographical evidence to‐date, as well as the latest evidence for the evolutionary and distributional history of tropical rain forests. Location Pantropical. Methods A pantropical termite species richness data set was obtained through sampling of eighty‐seven standardized local termite diversity transects from twenty‐nine locations across five tropical regions. Local‐scale, intermediate‐scale and large‐scale environmental data were collected for each transect. Standardized termite assemblage and environmental data were analysed at the levels of whole assemblages and feeding groups (using components of variance analysis) and at the level of functional taxonomic groups (using correspondence analysis and canonical correspondence analysis). Results Overall species richness of local assemblages showed a greater component of variation attributable to local habitat disturbance level than to region. However, an analysis accounting for species richness across termite feeding groups indicated a much larger component of variation attributable to region. Mean local assemblage body size also showed the greater overall significance of region compared with habitat type in influencing variation. Ordination of functional taxonomic group data revealed a primary gradient of variation corresponding to rank order of species richness within sites and to mean local species richness within regions. The latter was in the order: Africa > south America > south‐east Asia > Madagascar > Australia. This primary gradient of species richness decrease can be explained by a decrease in species richness of less dispersive functional taxonomic groups feeding on more humified food substrates such as soil. Hence, the transects from more depauperate sites/regions were dominated by more dispersive functional taxonomic groups feeding on less humified food substrates such as dead wood. Direct gradient analysis indicated that ‘region’ and other large‐scale factors were the most important in explaining patterns of local termite functional diversity followed by intermediate‐scale geographical and site variables and, finally, local‐scale ecological variables. Synthesis and main conclusions Within regions, centres of termite functional diversity lie in lowland equatorial closed canopy tropical forests. Soil feeding termite evolution further down food substrate humification gradients is therefore more likely to have depended on the long‐term presence of this habitat. Known ecological and energetic constraints upon contemporary soil feeders lend support for this hypothesis. We propose further that the anomalous distribution of termite soil feeder species richness is partly explained by their generally very poor dispersal abilities across oceans. Evolution, radiation and dispersal of soil feeder diversity appears to have been largely restricted to what are now the African and south American regions. The inter‐regional differences in contemporary local patterns of termite species richness revealed by the global data set point to the possibility of large differences in consequent ecosystem processes in apparently similar habitats on different continents.     

Biogenic magnetite as a basis for magnetic field detection in animals

Bacteria, sharks, honey bees, and homing pigeons as well as other organisms seem to detect the direction of the earth's magnetic field. Indirect but reproducible evidence suggests that the bees and birds can also respond to very minute changes in its intensity. The mechanisms behind this sensitivity are not known. Naturally magnetic, biologically precipitated magnetite (Fe₃O₄) has been found in chitons, magnetotactic bacteria, honey bees, homing pigeons, and dolphins. Its mineralization in localized areas may be associated with the ability of these animals to respond to the direction and intensity of the earth's magnetic field. The presence of large numbers (～10⁸) of superparamagnetic magnetite crystals in honey bees and similar numbers of single-domain magnetite grains in pigeons suggests that there may be at least two basic types of ferrimagnetic magnetoreceptive organelles. Theoretical calculations show that ferrimagnetic organs using either type of grain when integrated by the nervous system are capable of accounting for even the most extreme magnetic field sensitivities reported. Indirect evidence suggests that organic magnetite may be a common biological component, and may account for the results of numerous high field and electromagnetic experiments on animals.     

Obtaining of new magnetic nanocomposites based on modified polysaccharide

The study presents the preparation of some composite materials with magnetic properties by two different encapsulation methods of magnetite (Fe₃O₄) in a polymer matrix based on carboxymethyl starch-g-polylactic acid (CMS-g-PLA). The copolymer matrix used to obtain the magnetic nanocomposites was synthesized by grafting reaction of carboxymethyl starch (CMS) with d,l-lactic acid (DLLA), in the presence of Sn octanoate [Sn(Oct)₂] as catalyst. Magnetite was obtained by co-precipitation from aqueous salt solutions FeCl₂/FeCl₃ (molar ratio 1/2). The magnetic composites were prepared by precipitation method in acetone (non-solvent) of the DMSO solutions of magnetite and copolymer, and synthesis in situ of the nanocomposites. In the first case, the particle size measured by DLS-technique was 168 nm, and the magnetization was 46.82 emu/g, while after in situ synthesis, the composite materials showed smaller size (141 nm), but the magnetization was reduced (3.04 emu/g). The higher magnetization in the first case is due to the great degree of encapsulation of the magnetite, which was about 43.4 wt.%, compared to 4.37 wt.% for the in situ synthesis (determined by thermogravimetry). The CMS-g-PLA copolymer, magnetite, and the nanocomposites were characterized by infrared spectroscopy (FTIR), near infrared chemical imagistic (NIR-CI), dynamic light scattering (DLS) technique, X-ray diffraction (WAXD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and thermal analyses. Since the polymer matrix and magnetite are biodegradable and biocompatible, the magnetic nanocomposites can be used for conjugation of some drugs. The polymer matrix CMS-g-PLA acts as a shell, and vehicle for the active component, whereas magnetite is the component which makes targeting possible by external magnetic field manipulation.     

First evidence of wasp brood development inside active nests of a termite with the description of a previously unknown potter wasp species

Potter wasps (Vespidae: Eumeninae) are known to exhibit not only sophisticated preying strategies but also a remarkable ability to manipulate clay during nest building. Due to a mixture of plasticity in building behavior and flexibility in substrate preferences during nest building, the group has been reported nesting in a variety of places, including decaying nests abandoned by termite species. Yet, evidence of wasps nesting inside senescent termite mounds is poorly reported, and to date, accounts confirming their presence inside active colonies of termites are absent. Here, we address a novel intriguing association between two species from the Brazilian Cerrado: a previously unknown potter wasp (nest invader) and a termite species (nest builder). Besides scientifically describing Montezumia termitophila sp. nov. (Vespidae: Eumeninae), named after its association with the termite Constrictotermes cyphergaster (Silvestri, 1901) (Termitidae: Nasutitermitinae), we provide preliminary information about the new species'' bionomics by including (a) a hypothetical life cycle based on the evidence we collected and (b) a footage showing the first interaction between a recently ecloded wasp and a group of termites. In doing so, we attempt to provoke relevant discussions in the field and, perhaps, motivate further studies with the group. Finally, we describe a solution to efficiently detect and sample termitophilous species from termite nests, an intrinsic yet challenging task of any studies dealing with such a cryptic biological system.     

Effects of two locust control methods on wood-eating termites in arid Australia

Termites are ubiquitous detritivores and are a key influence on soil function and nutrient cycles, particularly in arid and semi-arid ecosystems. Locust control presents a unique hazard to termites and the effective functioning of ecosystems as a consequence of the overlap between pesticide applications and termite populations in grassland and desert landscapes. We monitored the effects of locust control methods using ultra-low-volume (ULV) barrier application of a chemical pesticide, fipronil, and a blanket application of a fungal biopesticide, Metarhizium acridum, on wood-eating termites in arid western New South Wales, Australia. We tested the hypothesis that spray applications decrease termite activity at wood baits using a BACI designed field experiment over 2 years. Our replicated control and treatment sites represented the spatial scale of Australian locust control activities. There was no detectable impact of either locust control treatment on termite activity, bait mass loss or termite community composition measures. Non-significant differences in termite survey measures among sites suggested that climate and environmental conditions were stronger drivers of our termite measures than the single, localized and unreplicated application of pesticides more commonly used in locust control operations in arid Australia. A lack of evidence for an impact of our fipronil or Metarhizium application methods supports their use as low hazard locust control options with minimal large scale and longer-term effects on termites in Australian arid rangelands. Future research would be necessary to determine the probable short-term impacts of treatments on individual termite colonies and the possible impacts on non-wood eating termite species in the arid-zone.     

Titanium and iron titanium oxide nanoparticles in antennae of the migratory ant <Emphasis Type="Italic">Pachycondyla marginata</Emphasis>: an alternative magnetic sensor for magnetoreception?

The most accepted hypothesis of magnetoreception for social insects is the ferromagnetic hypothesis which assumes the presence of magnetic material as a sensor coupled to sensitive structures that transmit the geomagnetic field information to the nervous system. As magnetite is the most common magnetic material observed in living beings, it has been suggested as basic constituent of the magnetoreception system. Antennae and head have been pointed as possible magnetosensor organs in social insects as ants, bees and termites. Samples of three antenna joints: head-scape, scape-pedicel and pedicel-third segment joints were embedded in epoxi resin, ultrathin sectioned and analyzed by transmission electron microscopy. Selected area electron diffraction patterns and X-ray energy dispersive spectroscopy were obtained to identify the nanoparticle compound. Besides iron oxides, for the first time, nanoparticles containing titanium have been identified surrounded by tissue in the antennae of ants. Given their dimension and related magnetic characteristics, these nanoparticles are discussed as being part of the magnetosensor system.