Here come the nouns: Czech two-year-olds use verb number endings to predict sentence subjects.

Two-year-old children can use gender or number agreement to predict upcoming words in phrases or sentences. However, most findings showed prediction from freestanding grammatical words, such as articles or copulas. While this shows knowledge of agreement relations, it might be limited to a narrow set of grammatical words. We examined the possibility that children at this age can use grammatical number agreement independently of specific closed-class words, testing whether they predict nouns from bound morphemes on lexical verbs. If this were the case, the emerging grammatical knowledge is unlikely to be lexically specific. Our first experiment replicated existing findings using number-marked copula, while the second experiment marked number on endings of four different verbs. Two-year-old children watched pairs of pictures showing single or multiple items while listening to sentences whose sentence-final subject referred to one of the two pictures. The grammatical Czech sentences contained a copula (Experiment 1: where is/are in the picture car/s?) or one of four number-marked lexical verbs (Experiment 2: Here jump/s the frog/s in the picture). Children in both experiments anticipated the subject from the verb or copula form. Children thus used number agreement predictively in the complex Czech copula system and lexical verbs marked by endings. This suggests that children understand grammatical number independently of specific grammatical words and supports the view that early knowledge of grammar is not lexically specific.

Czech 23-month-olds use gender agreement to anticipate upcoming nouns.

Children acquiring Dutch, French, and Spanish can use gender of articles to facilitate the processing of upcoming nouns. The current study examined whether a similar effect can be found for bound gender-marking agreement morphemes in Czech, a language without obligatory articles. The experiment was designed so that the anticipatory effects of gender-marking morphemes before the head noun onset could be observed. In a preferential looking experiment, 33 children (aged 21-24 months) were shown picture pairs that could be labeled with masculine and feminine nouns. They heard a phrase comprising a demonstrative, an adjective, and a noun, where the first two elements were inflected for gender. The inflections were either correct (matching the noun gender) or incorrect (mismatched). Children were also given offline receptive grammar and vocabulary tasks. The group of children as a whole did not show significant differences in looking behavior between the experimental conditions. When split by the grammar task, the high-scoring children showed significant differences between looks toward the target noun in the matched and mismatched conditions even before the onset of the target noun. No significant difference was observed in the low-scoring group and in the groups split by vocabulary. Results suggest that knowledge of the gender system is just emerging before the second birthday and that more advanced children can use gender information encoded in bound morphemes to actively anticipate the upcoming nouns.

The topography of rods, cones and intrinsically photosensitive retinal ganglion cells in the retinas of a nocturnal (Micaelamys namaquensis) and a diurnal (Rhabdomys pumilio) rodent.

We used immunocytochemistry to determine the presence and topographical density distributions of rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs) in the four-striped field mouse (Rhabdomys pumilio) and the Namaqua rock mouse (Micaelamys namaquensis). Both species possessed duplex retinas that were rod dominated. In R. pumilio, the density of both cones and rods were high (cone to rod ratio: 1:1.23) and reflected the species' fundamentally diurnal, but largely crepuscular lifestyle. Similarly, the ratio of cones to rods in M. namaquensis (1:12.4) reflected its nocturnal lifestyle. Similar rod density peaks were observed (R. pumilio: ~84467/mm2; M. namaquensis: ~81088/mm2), but a density gradient yielded higher values in the central (~56618/mm2) rather than in the peripheral retinal region (~32689/mm2) in R. pumilio. Two separate cone types (S-cones and M/L-cones) were identified implying dichromatic color vision in the study species. In M. namaquensis, both cone populations showed a centro-peripheral density gradient and a consistent S- to M/L-cone ratio (~1:7.8). In R. pumilio, S cones showed a centro-peripheral gradient (S- to M/L-cone ratio; central: 1:7.8; peripheral: 1:6.8) which appeared to form a visual streak, and a specialized area of M/L-cones (S- to M/L-cone ratio: 1:15) was observed inferior to the optic nerve. The number of photoreceptors per linear degree of visual angle, estimated from peak photoreceptor densities and eye size, were four cones and 15 rods per degree in M. namaquensis and 11 cones and 12 rods per degree in R. pumilio. Thus, in nocturnal M. namaquensis rods provide much finer image sampling than cones, whereas in diurnal/crepuscular R. pumilio both photoreceptor types provide fine image sampling. IpRGCs were comparably sparse in R. pumilio (total = 1012) and M. namaquensis (total = 862), but were homogeneously distributed in M. namaquensis and densest in the dorso-nasal quadrant in R. pumilio. The adaptive significance of the latter needs further investigation.

Characterization of pollen-expressed bZIP protein interactions and the role of ATbZIP18 in the male gametophyte.

KEY MESSAGE : bZIP TF network in pollen. Transcriptional control of gene expression represents an important mechanism guiding organisms through developmental processes and providing plasticity towards environmental stimuli. Because of their sessile nature, plants require effective gene regulation for rapid response to variation in environmental and developmental conditions. Transcription factors (TFs) provide such control ensuring correct gene expression in spatial and temporal manner. Our work reports the interaction network of six bZIP TFs expressed in Arabidopsis thaliana pollen and highlights the potential functional role for AtbZIP18 in pollen. AtbZIP18 was shown to interact with three other pollen-expressed bZIP TFs-AtbZIP34, AtbZIP52, and AtbZIP61 in yeast two-hybrid assays. AtbZIP18 transcripts are highly expressed in pollen, and at the subcellular level, an AtbZIP18-GFP fusion protein was located in the nucleus and cytoplasm/ER. To address the role of AtbZIP18 in the male gametophyte, we performed phenotypic analysis of a T-DNA knockout allele, which showed slightly reduced transmission through the male gametophyte. Some of the phenotype defects in atbzip18 pollen, although observed at low penetrance, were similar to those seen at higher frequency in the T-DNA knockout of the interacting partner, AtbZIP34. To gain deeper insight into the regulatory role of AtbZIP18, we analysed atbzip18/- pollen microarray data. Our results point towards a potential repressive role for AtbZIP18 and its functional redundancy with AtbZIP34 in pollen.

Magnetic alignment in carps: evidence from the Czech christmas fish market.

While magnetoreception in birds has been studied intensively, the literature on magnetoreception in bony fish, and particularly in non-migratory fish, is quite scarce. We examined alignment of common carps (Cyprinus carpio) at traditional Christmas sale in the Czech Republic. The sample comprised measurements of the directional bearings in 14,537 individual fish, distributed among 80 large circular plastic tubs, at 25 localities in the Czech Republic, during 817 sampling sessions, on seven subsequent days in December 2011. We found that carps displayed a statistically highly significant spontaneous preference to align their bodies along the North-South axis. In the absence of any other common orientation cues which could explain this directional preference, we attribute the alignment of the fish to the geomagnetic field lines. It is apparent that the display of magnetic alignment is a simple experimental paradigm of great heuristic potential.