A missense mutation in Katnal1 underlies behavioural, neurological and ciliary anomalies.

Microtubule severing enzymes implement a diverse range of tissue-specific molecular functions throughout development and into adulthood. Although microtubule severing is fundamental to many dynamic neural processes, little is known regarding the role of the family member Katanin p60 subunit A-like 1, KATNAL1, in central nervous system (CNS) function. Recent studies reporting that microdeletions incorporating the KATNAL1 locus in humans result in intellectual disability and microcephaly suggest that KATNAL1 may play a prominent role in the CNS; however, such associations lack the functional data required to highlight potential mechanisms which link the gene to disease symptoms. Here we identify and characterise a mouse line carrying a loss of function allele in Katnal1. We show that mutants express behavioural deficits including in circadian rhythms, sleep, anxiety and learning/memory. Furthermore, in the brains of Katnal1 mutant mice we reveal numerous morphological abnormalities and defects in neuronal migration and morphology. Furthermore we demonstrate defects in the motile cilia of the ventricular ependymal cells of mutants, suggesting a role for Katnal1 in the development of ciliary function. We believe the data we present here are the first to associate KATNAL1 with such phenotypes, demonstrating that the protein plays keys roles in a number of processes integral to the development of neuronal function and behaviour.

Identification of Sertoli cell-specific transcripts in the mouse testis and the role of FSH and androgen in the control of Sertoli cell activity.

BACKGROUND: The Sertoli cells act to induce testis differentiation and subsequent development in fetal and post-natal life which makes them key to an understanding of testis biology. As a major step towards characterisation of factors involved in Sertoli cell function we have identified Sertoli cell-specific transcripts in the mouse testis and have used the data to identify Sertoli cell-specific transcripts altered in mice lacking follicle-stimulating hormone receptors (FSHRKO) and/or androgen receptors (AR) in the Sertoli cells (SCARKO). RESULTS: Adult iDTR mice were injected with busulfan to ablate the germ cells and 50 days later they were treated with diphtheria toxin (DTX) to ablate the Sertoli cells. RNAseq carried out on testes from control, busulfan-treated and busulfan + DTX-treated mice identified 701 Sertoli-specific transcripts and 4302 germ cell-specific transcripts. This data was mapped against results from microarrays using testicular mRNA from 20 day-old FSHRKO, SCARKO and FSHRKO.SCARKO mice. Results show that of the 534 Sertoli cell-specific transcripts present on the gene chips, 85% were altered in the FSHRKO mice and 94% in the SCARKO mice (mostly reduced in both cases). In the FSHRKO.SCARKO mice additive or synergistic effects were seen for most transcripts. Age-dependent studies on a selected number of Sertoli cell-specific transcripts, showed that the marked effects in the FSHRKO at 20 days had largely disappeared by adulthood although synergistic effects of FSHR and AR knockout were seen. CONCLUSIONS: These studies have identified the Sertoli cell-specific transcriptome in the mouse testis and have shown that most genes in the transcriptome are FSH- and androgen-dependent at puberty although the importance of FSH diminishes towards adulthood.

Cell-specific ablation in the testis: what have we learned?

Testicular development and function is the culmination of a complex process of autocrine, paracrine and endocrine interactions between multiple cell types. Dissecting this has classically involved the use of systemic treatments to perturb endocrine function, or more recently, transgenic models to knockout individual genes. However, targeting genes one at a time does not capture the more wide-ranging role of each cell type in its entirety. An often overlooked, but extremely powerful approach to elucidate cellular function is the use of cell ablation strategies, specifically removing one cellular population and examining the resultant impacts on development and function. Cell ablation studies reveal a more holistic overview of cell-cell interactions. This not only identifies important roles for the ablated cell type, which warrant further downstream study, but also, and importantly, reveals functions within the tissue that occur completely independently of the ablated cell type. To date, cell ablation studies in the testis have specifically removed germ cells, Leydig cells, macrophages and recently Sertoli cells. These studies have provided great leaps in understanding not possible via other approaches; as such, cell ablation represents an essential component in the researchers' tool-kit, and should be viewed as a complement to the more mainstream approaches to advancing our understanding of testis biology. In this review, we summarise the cell ablation models used in the testis, and discuss what each of these have taught us about testis development and function.

The effect of dihydrotestosterone exposure during or prior to the masculinization programming window on reproductive development in male and female rats.

Masculinization is programmed by androgen exposure during a masculinization programming window (MPW). Deficiency in MPW androgen action results in reduced size of all reproductive organs and anogenital distance (AGD) and reproductive disorders. Although timing of MPW closing has been defined, what determines 'opening' and 'closing' of the MPW remains unknown. To test whether initiation of testosterone production/action defines the opening of the window, we first demonstrated that androgen receptor mRNA and protein are expressed prior to the MPW, and then investigated whether masculinization could be advanced or enhanced by treating pregnant rats with either 1 or 10 mg/kg/day dihydrotestosterone (DHT) prior to (early window, EW; e11.5-e14.5) or during the MPW (e15.5-e18.5), and then evaluating offspring in foetal life (e18.5, e21.5), early puberty (day 25) or adulthood (∼day 75). DHT treatment did not affect pregnancy duration, birth, litter or pup size. DHT exposure in either time window did not advance foetal male development (Wolffian duct coiling) and had no effect on AGD, testis, penis and ventral prostate (VP) size at any age when measured; there was a tendency towards smaller penis size. In contrast, exposure of females to 10 mg DHT in either time window induced varying degrees of masculinization, including stabilization of the Wolffian duct and increased AGD (e21.5, Pnd25), VP formation, more male-like phallus structure, absence of nipples and vaginal opening and, in some adult females, gross fluid distension of the uterus (hydrometrocolpos); these effects were generally more pronounced after exposure in the MPW than in the EW. In conclusion, exposure of the male rat foetus to additional androgens prior to or during the MPW does not advance or enhance any measured parameter of reproductive development. Therefore, androgen availability plays no role in determining timing of the MPW. Susceptibility of the female reproductive system to androgens may precede the MPW.

Androgen receptor signalling in peritubular myoid cells is essential for normal differentiation and function of adult Leydig cells.

Testosterone synthesis depends on normal Leydig cell (LC) development, but the mechanisms controlling this development remain unclear. We recently demonstrated that androgen receptor (AR) ablation from a proportion of testicular peritubular myoid cells (PTM-ARKO) did not affect LC number, but resulted in compensated LC failure. The current study extends these investigations, demonstrating that PTM AR signalling is important for normal development, ultrastructure and function of adult LCs. Notably, mRNAs for LC markers [e.g. steroidogenic factor 1 (Nr5a1), insulin-like growth factor (Igf-1) and insulin-like factor 3 (Insl3)] were significantly reduced in adult PTM-ARKOs, but not all LCs were similarly affected. Two LC sub-populations were identified, one apparently 'normal' sub-population that expressed adult LC markers and steroidogenic enzymes as in controls, and another 'abnormal' sub-population that had arrested development and only weakly expressed INSL3, luteinizing hormone receptor, and several steroidogenic enzymes. Furthermore, unlike 'normal' LCs in PTM-ARKOs, the 'abnormal' LCs did not involute as expected in response to exogenous testosterone. Differential function of these LC sub-populations is likely to mean that the 'normal' LCs work harder to compensate for the 'abnormal' LCs to maintain normal serum testosterone. These findings reveal new paracrine mechanisms underlying adult LC development, which can be further investigated using PTM-ARKOs.

Early effects of Sertoli cell-selective androgen receptor ablation on testicular gene expression.

Evidence from several models of hormone depletion and/or replacement and from knockout animals points to a key role of androgens in the control of spermatogenesis. In testes of mice with a Sertoli cell-selective ablation of the androgen receptor (SCARKO), transcriptional profiling, using microarray technology, revealed that, already on postnatal day 10,692 genes are differentially expressed compared with testes of control mice. Further evaluation of a subset of these genes by quantitative RT-PCR suggested that differences in expression may already be evident on day 8 or earlier. As the androgen receptor in mouse Sertoli cells becomes immunologically detectable around day 5, we tried to identify the earliest responses to androgens by a new transcriptional profiling study on testes from 6-day-old SCARKO and control mice. No obvious and novel early androgen response genes, potentially acting as mediators of subsequent indirect androgen actions, could be identified. However, several genes differentially expressed on day 10 already displayed a response to androgen receptor ablation on day 6. Quantitative RT-PCR studies for 12 of these genes on 10 paired SCARKO and control testes from 4-, 6-, 8-, 10-, 20- and 50-day-old mice revealed significant differences in expression level from day 4 onwards for three genes (Eppin, PCI, Cldn11) and from day 6 onwards for one more gene (Rhox5). For at least two of these genes (Rhox5 and Eppin), there is evidence for direct regulation via the androgen receptor. For three additional genes (Gpd1, Tubb3 and Tpd52l1) significantly lower expression in the SCARKO was noted from day 8 onwards. For all the studied genes, an impressive increase in transcript levels was observed between day 4-50 and differential expression was maintained in adulthood. It is concluded that the SCARKO model indicates incipient androgen action in mouse Sertoli cells from day 4 onwards.

Enhanced skeletal growth of sheep heterozygous for an inactivated fibroblast growth factor receptor 3.

Normal fibroblast growth factor receptor 3 (FGFR3) acts as a negative bone growth regulator by restricting chondrocyte proliferation and endochondral bone elongation. In sheep, a heritable mutation that inactivates FGFR3 produces skeletal overgrowth when homozygous, this condition is commonly referred to as spider lamb syndrome (SLS). We hypothesized that sheep heterozygous for the inactivated FGFR3 mutation (FGFR3(SLS/+)) would exhibit enhanced long bone growth and greater frame size; additionally, the isolated effects of increased bone growth would translate into greater BW and larger LM area relative to normal lambs at harvest. The current study investigated bone length and LM area of FGFR3(SLS/+) sheep at maturity and during growth. At maturity, FGFR3(SLS/+) ewes exhibited a larger frame size and longer bones than normal FGFR3(+/+) ewes (P < 0.05). Similarly, FGFR3(SLS/+) lambs had greater frame sizes than normal FGFR3(+/+) lambs, as indicated by increased metacarpal III length and height at withers (P < 0.05). The FGFR3(SLS/+) lambs took longer than the normal FGFR3(+/+) lambs to reach the 60-kg common BW harvest end point (P < 0.05). The FGFR3(SLS/+) lambs showed no difference in BW, ADG, or LM area at any age compared with normal FGFR3(+/+) lambs (P > 0.2). A similar LM area produced in the context of a greater frame size and skeletal length produces a greater muscle volume, thereby potentially increasing meat yield. The results of this study suggest that FGFR3(SLS/+) animals exhibit a relaxation of the normal inhibition of chondrocyte proliferation, resulting in an increase in the overall frame size. The sheep industry could utilize the naturally occurring genetic mutation in FGFR3 to potentially increase meat yields with enhanced skeletal growth as an alternative to exogenous growth promotants.

Dissociation of body growth and adipose deposition effects of growth hormone in oMt1a-oGH transgenic mice.

Chronic highly elevated expression of a growth hormone (GH) transgene enhances overall body growth with minimal adipose accretion, while moderate levels of circulating GH fail to enhance body growth yet promote adipose deposition. These findings suggest that the growth response to GH can be dissociated from adipose effects. This hypothesis was tested in the oMtla-oGH transgenic mouse model by titrating circulating GH levels through variable induction of transgene expression. Circulating GH levels in female transgenics were approximately 49, 132, and 750 ng/ml in response to the transgene stimulus at 0, 15, and 25 mM zinc sulfate, respectively. The highest level of circulating GH generated the largest body weight with the smallest fat accrual while the intermediate GH level generated a body weight equivalent to that for the highest GH but the heaviest gonadal fat pads. The lowest GH levels did not increase body size but did enlarge fat depots. Animals exposed to the highest level of GH had an extended growth phase relative to lower GH levels and the nontransgenic controls. In contrast, the duration of the growth phase for the 0 and 15 mM zinc stimulated transgenics was abbreviated relative to the growth phase of the control animals. The two highest levels of circulating GH increased all forms of the GH receptor, IGF-I, and hepatic lipoprotein lipase mRNA. The growth differential observed for the 0 vs. the 15 mM zinc stimulated transgenics may reflect the preferential increase in the full length GH receptor mRNA and the induction of the smaller IGF-I transcripts with the higher circulating GH while the lipid accrual paralleled the disproportionate induction of the truncated GH receptor mRNA form. Liver and bone content of zinc, manganese, copper, and iron primarily reflected dietary zinc supplementation and did not appear to play a role in the differential growth response. The dissociation of GH effects on growth and adipogenesis as a function of circulating GH levels suggests that the level of GHR and IGF-I expression acts through a threshold mechanism and low expression results in adipogenesis while high expression generates body growth.

Tests of a dynamic systems account of the A-not-B error: the influence of prior experience on the spatial memory abilities of two-year-olds.

Recently, Smith, Thelen, and colleagues proposed a dynamic systems account of the Piagetian "A-not-B" error in which infants' errors result from general processes that make goal-directed actions to remembered locations. Based on this account, the A-not-B error should be a general phenomenon, observable in different tasks and at different points in development. Smith, Thelen, et al.'s proposal was tested using an A-not-B version of a sandbox task. During three training trials and three "A" trials, 2-year-olds watched as a toy was buried in a sandbox at Location A. Following a 10-s delay, children searched for the object. Across five experiments, children's (total N = 92) performance on the A trials was accurate. After the A trials, children watched as a toy was hidden at Location B, 8 to 10 inches from Location A. In all experiments, children's searches after a 10-s delay were significantly biased in the direction of Location A. Furthermore, this bias toward Location A decreased with repeated trials to Location B, as well as when children completed fewer trials to Location A. Together, these data suggest that A-not-B-type errors are pervasive across tasks and development.

Early noun lexicons in English and Japanese.

Previous research suggests that children learning a variety of languages acquire similar early noun vocabularies and do so by similar and universal processes. We report here results from two studies that show differences in the early noun learning of English- and Japanese-speaking children. Experiment 1 examined the relative numbers of animal names and object names in vocabularies of English-speaking and Japanese-speaking children. English-speaking children's vocabularies were heavily lopsided with many more object than animal names whereas Japanese-speaking children's vocabularies were more evenly balanced. Experiment 2 used a novel noun extension task to examine what young children know about the different organizations of animal and artifact categories. The results suggest that early learners of English but not Japanese over-generalize what they know about object categories to animal categories. The role of culture, input and linguistic structure in early noun acquisitions is discussed.

Contrasting genome organisation: two regions of the Brassica oleracea genome compared with collinear regions of the Arabidopsis thaliana genome.

Brassica crop species are of worldwide importance and are closely related to the model plant Arabidopsis thaliana for which the complete genome sequence has recently been established. We investigated collinearity of marker order by comparing two contrasting regions of the Brassica oleracea genome with homologous regions of A. thaliana. Although there is widespread replication of marker loci in both A. thaliana and B. oleracea, we found that a combination of genetic markers mapped in B. oleracea, including RFLPs, CAPS, and SSRs allowed comparison and interpretation of medium-scale chromosomal organisation and rearrangements. The interpretation of data was facilitated by hybridising probes onto the whole A. thaliana genome, as represented by BAC contigs. Twenty marker loci were sampled from the whole length of the shortest B. oleracea linkage group, 06, and 21 from a 30.4-cM section of the longest linkage group, 03. There is evidence of locus duplication on linkage group 06. Locus order is well conserved between a putative duplicated region of 10.5 cM and a discrete region comprising 25 cM of A. thaliana chromosome I. This was supported by evidence from seven paralogous loci, three of which were duplicated in a 30.6-cM region of linkage group 06. The pattern of locus order for the remainder of linkage group 06 and the sampled section of linkage group 03 was more complex when compared with the A. thaliana genome. Although there was some conservation of locus order between markers on linkage group 03 and approximately 9 cM of A. thaliana chromosome I, this was superimposed upon a complex pattern of additional loci that were replicated in both A. thaliana and B. oleracea. The results are discussed in the context of the ability to use collinear information to assist map-based cloning.

The dynamics of embodiment: a field theory of infant perseverative reaching.

The overall goal of this target article is to demonstrate a mechanism for an embodied cognition. The particular vehicle is a much-studied, but still widely debated phenomenon seen in 7-12 month-old-infants. In Piaget's classic "A-not-B error," infants who have successfully uncovered a toy at location "A" continue to reach to that location even after they watch the toy hidden in a nearby location "B." Here, we question the traditional explanations of the error as an indicator of infants' concepts of objects or other static mental structures. Instead, we demonstrate that the A-not-B error and its previously puzzling contextual variations can be understood by the coupled dynamics of the ordinary processes of goal-directed actions: looking, planning, reaching, and remembering. We offer a formal dynamic theory and model based on cognitive embodiment that both simulates the known A-not-B effects and offers novel predictions that match new experimental results. The demonstration supports an embodied view by casting the mental events involved in perception, planning, deciding, and remembering in the same analogic dynamic language as that used to describe bodily movement, so that they may be continuously meshed. We maintain that this mesh is a pre-eminently cognitive act of "knowing" not only in infancy but also in everyday activities throughout the life span.

The role of target distinctiveness in infant perseverative reaching.

From a dynamic systems perspective, perseverative errors in infancy arise from the interaction of the perceptual cues with the memory of previous actions. To evaluate this account, we tested 9-month-old infants in a task in which they reached for two targets. Experimenters repeatedly cued the first target, which always matched the background (A), and then cued the second target, which varied in its distinctiveness (B). We predicted that a sufficiently distinctive B target would lessen perseverative responding. Results showed that infants perseverated when reaching for two identical targets, but that they made nonperseverative responses when reaching in the presence of a highly distinctive B target. Reach direction on each trial was jointly determined by the distinctiveness of the target, the immediately preceding perceptual events, and the history of reaches in the task.

Why children learn color and size words so differently: evidence from adults' learning of artificial terms.

An adult simulation study examined why children's learning of color and size terms follow different developmental patterns, one in which word comprehension precedes success in nonlinguistic matching tasks versus one in which matching precedes word comprehension. In 4 experiments, adults learned artificial labels for values on novel dimensions. Training mimicked that characteristic for children learning either color words or size words. The results suggest that the learning trajectories arise from the different frames in which different dimensions are trained: Using a comparison (size-like) training regimen helps learners pick out the relevant dimension, and using a categorization (color-like) training regimen helps the learner correctly comprehend and produce dimension terms. The results indicate that the training regimen, not the meanings of the terms or the specific dimensions, determines the pattern of learning.

Counting nouns and verbs in the input: differential frequencies, different kinds of learning?

Previous research has focused on evaluating the nouns and verbs in parents' input through type/token ratios. This research offers an additional means of evaluating parent speech by first examining the frequencies of individual nouns, verbs and descriptors and second examining the learning task presented to children. Study 1 examines 25 transcripts from the CHILDES database of English-speaking parents' speech to children at five developmental levels ranging from 0;11 to 2;11 in age. Study 2 examines 50 transcripts from the CHILDES database of Mandarin-speaking caregivers' speech to children ranging from 1;9 to 2;3 in age. The results suggest that the patterns of frequency for individual nouns and individual verbs are different, but that the frequency patterns for nouns and the frequency patterns for verbs are similar in English and Mandarin. Further, this research suggests that in both languages the nouns in parents' input are similarly organized: the most frequent nouns spoken to children tend to name solid objects that share a similar shape. In contrast verbs' meanings in both languages tend to include more variable conceptual relations.

Real-time and integrated measurement of potential human exposure to particle-bound polycyclic aromatic hydrocarbons (PAHs) from aircraft exhaust.

We used real-time monitors and low-volume air samplers to measure the potential human exposure to airborne polycyclic aromatic hydrocarbon (PAH) concentrations during various flight-related and ground-support activities of C-130H aircraft at an Air National Guard base. We used three types of photoelectric aerosol sensors (PASs) to measure real-time concentrations of particle-bound PAHs in a break room, downwind from a C-130H aircraft during a four-engine run-up test, in a maintenance hangar, in a C-130H aircraft cargo bay during cargo-drop training, downwind from aerospace ground equipment (AGE), and in a C-130H aircraft cargo bay during engine running on/off (ERO) loading and backup exercises. Two low-volume air samplers were collocated with the real-time monitors for all monitoring events except those in the break room and during in-flight activities. Total PAH concentrations in the integrated-air samples followed a general trend: downwind from two AGE units > ERO-loading exercise > four-engine run-up test > maintenance hangar during taxi and takeoff > background measurements in maintenance hangar. Each PAH profile was dominated by naphthalene, the alkyl-substituted naphthalenes, and other PAHs expected to be in the vapor phase. We also found particle-bound PAHs, such as fluoranthene, pyrene, and benzo[a]pyrene in some of the sample extracts. During flight-related exercises, total PAH concentrations in the integrated-air samples were 10-25 times higher than those commonly found in ambient air. Real-time monitor mean responses generally followed the integrated-air sample trends. These monitors provided a semiquantitative temporal profile of ambient PAH concentrations and showed that PAH concentrations can fluctuate rapidly from a baseline level < 20 to > 4,000 ng/m(3) during flight-related activities. Small handheld models of the PAS monitors exhibited potential for assessing incidental personal exposure to particle-bound PAHs in engine exhaust and for serving as a real-time dosimeter to indicate when respiratory protection is advisable.

Adults' acquisition of novel dimension words: creating a semantic congruity effect.

The semantic congruity effect is exhibited when adults are asked to compare pairs of items from a series, and their response is faster when the direction of the comparison coincides with the location of the stimuli in the series. For example, people are faster at picking the bigger of 2 big items than the littler of 2 big items. In the 4 experiments presented, adults were taught new dimensional adjectives (mal/ler and borg/er). Characteristics of the learning situation, such as the nature of the stimulus series and the relative frequency of labeling, were varied. Results revealed that the participants who learned the relative meaning of the artificial dimensional adjectives also formed categories and developed a semantic congruity effect regardless of the characteristics of training. These findings have important implications for our understanding of adult acquisition of novel relational words, the relationship between learning such words and categorization, and the explanations of the semantic congruity effect.

Grounding development in cognitive processes.

Developmentalists have made remarkable progress over the last several decades in detailing what children know at various points in development. Less progress has been made, however, in detailing the processes through which knowledge is realized in real-time tasks, or in detailing the processes of developmental change. We argue that the operating characteristics of perceiving and remembering provide a foundation for making progress on these issues in the next century. We include three examples applying these ideas to specific phenomena in early word learning. These examples illustrate how forming developmental hypotheses in terms of perceiving and remembering may bring new insights into specific phenomena as well as into how the ordinary operating characteristics of perceiving and remembering serve as bootstraps to more specialized and more abstract kinds of knowledge.

Exposures to jet fuel and benzene during aircraft fuel tank repair in the U.S. Air Force.

Jet fuel and benzene vapor exposures were measured during aircraft fuel tank entry and repair at twelve U.S. Air Force bases. Breathing zone samples were collected on the fuel workers who performed the repair. In addition, instantaneous samples were taken at various points during the procedures with SUMMA canisters and subsequent analysis by mass spectrometry. The highest eight-hour time-weighted average (TWA) fuel exposure found was 1304 mg/m3; the highest 15-minute short-term exposure was 10,295 mg/m3. The results indicate workers who repair fuel tanks containing explosion suppression foam have a significantly higher exposure to jet fuel as compared to workers who repair tanks without foam (p < 0.001). It is assumed these elevations result from the tendency for fuel, absorbed by the foam, to volatilize during the foam removal process. Fuel tanks that allow flow-through ventilation during repair resulted in lower exposures compared to those tanks that have only one access port and, as a result, cannot be ventilated efficiently. The instantaneous sampling results confirm that benzene exposures occur during fuel tank repair; levels up to 49.1 mg/m3 were found inside the tanks during the repairs. As with jet fuel, these elevated benzene concentrations were more likely to occur in foamed tanks. The high temperatures associated with fuel tank repair, along with the requirement to wear vapor-permeable cotton coveralls for fire reasons, could result in an increase in the benzene body burden of tank entrants.