Search

Odontepyris costatus sp. nov. is described from Japan and Taiwan. This new species is most similar to O. formosicola Terayama, 1997 known from Cambodia and Taiwan according to the key to the Eastern Palaearctic Odontepyris. O. costatus sp. nov. can be distinguished from the latter by the relatively small eye and the wide metapectal-propodeal disc. It is also similar to O. telortis Lim & Lee, 2009 known from South Korea, but it is distinguished from O. telortis by the imbricate median area of metapostnotum. The morphological variations and diagnostic characters of the Eastern Palaearctic species are briefly discussed and the modified key to species is provided. Key words: new species, Japan, Taiwan, wing venation

A new species, Olyra parviocula, is described from the Kameng River, Brahmaputra River drainage in Arunachal Pradesh, northeastern India. The new species differs from congeners in having small eye diameter 5–8% HL; short adipose fin, not confluent with caudal-fin, its base length 9–12% SL; dorsal-fin branched rays 6; anal-fin rays viii–xi, 8–10 and maxillary barbel almost reaching pelvic-fin base. A key to identification of all valid species of Olyra is provided.

Molecules of the hedgehog (hh) family are involved in the specification and patterning of eyes in vertebrates and invertebrates. These organs, though, are of very different sizes, raising the question of how Hh molecules operate at such different scales. In this paper we discuss the strategies used by Hh to control the development of the two eye types in Drosophila: the large compound eye and the small ocellus. We first describe the distinct ways in which these two eyes develop and the evidence for the key role played by Hh in both; then we consider the potential for variation in the range of action of a "typical" morphogen and measure this range ("characteristic length") for Hh in different organs, including the compound eye and the ocellus. Finally, we describe how different feedback mechanisms are used to extend the Hh range of action to pattern the large and even the small eye. In the ocellus, the basic Hh signaling pathway adds to its dynamics the attenuation of its receptor as cell differentiate. This sole regulatory change can result in the decoding of the Hh gradient by receiving cells as a wave of constant speed. Therefore, in the fly ocellus, the Hh morphogen adds to its spatial patterning role a novel one: patterning along a time axis.

Prochilodus argenteus is an endemic fish species from the São Francisco River basin that is of high economic and environmental importance. The present study aimed to contribute with information to the taxonomic identification of larvae and juveniles of this species. Larvae , obtained from induced spawning of wild animals, were reared in ponds. Individuals were collected daily and classified into larval stages or juvenile phase. Morphological descriptions and morphometric measurements were performed, together with a piece wise linear regression analysis of the body proportions throughout the development process. Individuals in the preflexion stage had a standard length (SL) of 4.48 to 6.64mm, long to moderate body (BH/SL), small to moderate head (HL/SL), and a small to moderate eye (ED/HL). In the flexion stage, the SL varied from 6.60 to 11.00mm, long to moderate body, moderate head, and small to moderate eye. Larvae in the postflexion stage presented SL of 10.54-19.93mm, moderate body, moderate to big head and small eye. The juvenile phase included specimens with a SL of 18.27 to 42.21mm which presented a moderate to high body, big head and small to moderate eye. Regression analysis showed significant moments of change in rate of increase of the body proportions, presenting a change in the growth pattern from allometry to isometry during the early development.

I describe two distinctive new species of elapid snakes of the genus Toxicocalamus from the southeastern end of Papua New Guinea. The first species, T. mintoni sp. nov., is unique within the genus in having the frontal fused with the supraoculars. It is a fairly gracile species of uniformly light-brown coloration and is known from only a single specimen from central Sudest Island. The second species, T. pachysomus sp. nov., is unique in its combination of having a distinct preocular unfused with the prefrontal, the internasal in contact with the preocular, the second supralabial in contact with the nasal, and paired subcaudals. Its stout habitus is unique within the genus, and its small eye is also distinctive. This species too is known from only a single specimen from the Cloudy Mountains, the southeasternmost portion of the island of New Guinea. Milne Bay Province, which is comprised of the southeastern extremity of New Guinea and its adjacent offshore islands, is a center of diversity for the ...

Diaphanosoma edmondsoni sp. nov. is described from material from several lakes in Washington, California, and Montana. It differs from all other known species of the genus in having a specific combination of traits: a head with conspicuously protruding dorsal part, comparatively small eye shifted ventrally, specific armament of postero-ventral valve margin, lack of thorn(s) near posterior valve margin, comparatively long distal basal spine of postabdominal claws of slightly variable shape, and occasional presence of additional large spines on the claws. This is the first endemic species of the genus (and also of the family Sididae and order Ctenopoda) recorded in the western part of North America, which along with some other cladocerans form a group of taxa highlighting this region as one of the regional centers of endemic aquatic fauna.

Pax6, a member of the paired-family of transcription factors, exhibits restricted expression and essential functions in the developing eye, olfactory system, central nervous system, and pancreas. To understand Pax6 function, which critically depends on induction of proper expression levels during development, it is necessary to elucidate the molecular mechanisms governing Pax6 transcription. Although previous studies using classic transgenic approaches have provided a wealth of information about the distribution and types of regulatory elements involved in Pax6 regulation, genetic studies in both humans and mice indicate that these enhancers alone are not sufficient for fully regulated Pax6 expression. We report here our analysis of mice transgenic for a 160 kb mouse Pax6 BAC transgene, which was generated as a necessary first step towards testing the long-range control of Pax6 expression in vivo. We show that this BAC transgene replicates Pax6 expression in the eye. This is the first time that a reporter transgene has been expressed in a normal Pax6-like pattern in all of the tissues of the eye and defines an eye regulatory region within the Pax6 downstream regulatory region (DRR). Second, we show that this BAC transgene contains all of the cis regulatory elements required for normal Pax6 expression within the developing embryo, except for within the diencephalon and olfactory bulb. Third, we show that this transgene is subject to Pax6 autoregulation. Lastly, we identify, for the first time in mammals, an isoform of the Pax6 protein lacking the paired domain. This isoform is expressed in the developing olfactory bulb and eye. Over-expression of Pax6DeltaPD causes a microphthalmic phenotype in both Pax6(+/+) mice and Pax6(+/-) mice. These results demonstrate a role for Pax6DeltaPD in eye development, which appears to be different than that ascribed to either canonical Pax6 or Pax6(5a).

The light environment of the mesopelagic realm of the ocean changes with both depth and viewer orientation, and this has probably driven the high diversity of visual adaptations found among its inhabitants. The mesopelagic ‘cockeyed’ squids of family Histioteuthidae have unusual eyes, as the left and right eyes are dimorphic in size, shape and sometimes lens pigmentation. This dimorphism may be an adaptation to the two different sources of light in the mesopelagic realm, with the large eye oriented upward to view objects silhouetted against the dim, downwelling sunlight and the small eye oriented slightly downward to view bioluminescent point sources. We used in situ video footage from remotely operated vehicles in the Monterey Submarine Canyon to observe the orientation behaviour of 152 Histioteuthis heteropsis and nine Stigmatoteuthis dofleini . We found evidence for upward orientation in the large eye and slightly downward orientation in the small eye, which was facilitated by a tail-up oblique body orientation. We also found that 65% of adult H. heteropsis ( n = 69) had yellow pigmentation in the lens of the larger left eye, which may be used to break the counterillumination camouflage of their prey. Finally, we used visual modelling to show that the visual returns provided by increasing eye size are much higher for an upward-oriented eye than for a downward-oriented eye, which may explain the development of this unique visual strategy. This article is part of the themed issue ‘Vision in dim light’.

A new ogcocephalid batfish,Coelophrys bradburyae, is described on the basis of a single specimen collected from the Pacific coast off Aomori, Japan, at a depth between 557–595 m. The species differs from others of the genus by having a small eye (7.1 in head length), short upper jaw (3.7 in head length), short pectoral and pelvic fins (length 3.0 and 9.6 in head length, respectively), small illicial cavity (width 5.3 in head length), and no bifurcated tubercles on the lateral surface of the body. A key to the species ofCoelophrys is given and the evolutionary relationships of the genus discussed based on cladistic analyses: the sister relationship withHalieutopsis was confirmed and possible paedomorphic states, including the globose body, proposed as having evolved secondarily from a flat-bodied ogcocephalid ancestor.

Anophthalmia or microphthalmia (A/M), characterized by absent or small eye, can be unilateral or bilateral and represent developmental anomalies due to the mutations in several genes. Recently, mutations in aldehyde dehydrogenase family 1, member A3 (ALDH1A3) also known as retinaldehyde dehydrogenase 3, have been reported to cause A/M. Here, we screened a cohort of 75 patients with A/M and showed that mutations in ALDH1A3 occurred in six families. Based on this series, we estimate that mutations in ALDH1A3 represent a major cause of A/M in consanguineous families, and may be responsible for approximately 10% of the cases. Screening of this gene should be performed in a first line of investigation, together with SOX2. (C) 2014 Wiley Periodicals, Inc.

The genus Sinopoda Jager, 1999 is recorded for the first time in Laos. Nine new species are described: Sinopoda steineri spec. nov. (female; Luang Nam Tha), S. tham spec. nov. (male, female; Oudomxai), S. sitkao spec. nov. (female; Luang Prabang), S. taa spec. nov. (female; Luang Prabang), S. suang spec. nov. (female; Huaphan), S. peet spec. nov. (female; Huaphan), S. guap spec. nov. (female; Khammuan), S. soong spec. nov. (female; Khammuan), S. scurion spec. nov. (female; Khammuan). All species have been collected from caves. Sinopoda scurion spec. nov. represents the first record of an eyeless huntsman spider, S. guap spec. nov. exhibits only small lenses of six eyes (AME lacking), S. soong spec. nov. has only two small eye lenses. Four immature individuals ( Sinopoda sp. indet. A–D) exhibited a reduced size or number of eyes, they are listed including their localities although they could not be identified to species level.

Holosprosencephaly (HPE) is the most common disorder of the developing forebrain in humans, and is characterized by failed or incomplete cleavage of the cerebral hemispheres and deep brain structures. HPE includes wide phenotypic variability, with a continuum of both brain and craniofacial anomalies.

Two new species of the sciaenid genusJohnius (Johnius) are described:J. trewavasae from Taiwan, Hong Kong, and Singapore, differs from all other congeners in having 24–27 dorsal soft rays, 5–6 scales above and 7–10 scales below the lateral line, 6–8 obtuse lower gill rakers, the last pleural rib on the 11th vertebra, and a shorter lower jaw (33.8–38.4% HL);J. latifrons from Thailand and Java is characterized by 25–29 dorsal soft rays, 7–9 scales above and 11–14 scales below the lateral line, 7–9 obtuse lower gill rakers, a wide interorbital width (26.1–30.6% HL), a small eye (16.7–26.4% HL), and a short, second anal spine (25.9–37.1% HL). Two related species,J. heterolepis Bleeker from “Suriname” andJ. cantori Bleeker from Malaya, are resurrected as valid West Pacific species of Johnius (Johnius).

Black iguana are eaten by human and other predators in Costa Rica. The importance of eye size on avoidance and recovery behaviour of black iguana was examined using an approaching person as the stimulus. Iguanas moved and ran earlier when the approaching person wore a large eye mask than when she wore a smaller eye mask. Iguana response did not vary during the tests as a function of snoutvent length, but response variables were generally correlated. Black iguana clearly moved and ran earlier in response to a large compared with a small eye, indicating they perceive and monitor this feature of predators.

Pax6 mutations cause complex ocular malformations, but it is uncertain whether early eye development normally requires Pax6 function in both the optic vesicle (OV) and the lens epithelium, or only in the latter. To investigate this question, we electroporated the OV with anti-Pax6 or control morpholinos before the onset of lens placode formation. Pax6 downregulation was already detectable in the OV 10 h after anti-Pax6 treatment, and was accompanied by a significant increase in the death of OV cells. A small eye-like phenotype developed thereafter, whose severity was developmental stage-dependent. When treatment was applied at Hamburger Hamilton (HH) stage 10, there was no optic cup formation, and lens development was abortive despite normal Pax6 expression in the lens epithelium. Treatment at HH stage 11 resulted in structurally normal lens and optic cup, although the latter showed abnormal expression domains for several transcription factors. Early eye development therefore requires cell-autonomous Pax6 function not only in the lens but also in the optic vesicle, where it plays a hitherto unknown role in cell survival. The results, moreover, indicate that there is a critical stage during which Pax6 expression in the OV is necessary for normal lens development.

The transcription factor Pax6 plays a pivotal role in eye development, as eye morphogenesis is arrested at a primitive optic vesicle stage in homozygous Pax6 mutant mouse embryos. The arrested optic vesicle development has led to the assumption that cellular differentiation programs are unable to initiate. Contrary to this, we found that neurogenesis in Pax6 mutant optic vesicles was not arrested, but instead accelerated as numerous neurons differentiated precociously, more than a day earlier than normal. To identify potential mechanisms for Pax6 repression of neuron differentiation, we examined retinal proliferation and differentiation. Mutant optic vesicles had reduced proliferation, coupled with precocious activation of the proneural gene, Mash1. Ectopic expression of Mash1 was sufficient to induce precocious neuron differentiation. Subsequently, precocious neurons adopted a generic rather than a specific retinal neuron fate. Thus, Pax6 regulates the timing of retinal neurogenesis and couples it with specific neuron differentiation programs.

Pax6 g ene encodes a transcription factor that plays a pivotal role in various aspects of brain development. Here I review the molecular and cellular mechanisms of how the early brain is patterned, and introduce recent studies on the role of Pax6 in brain patterning, neuronal specification, neuronal migration and axonal extension.

Two new species of Glyptothorax are described from the rivers draining the Annam Cordilleras in central Vietnam. Glyptothorax filicatus n. sp. is distinguished from congeners in Indochina in having a diverging pattern of striae running along the edges of the central depression in the thoracic adhesive apparatus, and a combination of the following characters: dorsal spine length 13.7–15.1% SL, pectoral fin length 21.5–21.9% SL, length of adipose-fin base 13.3–15.0% SL, depth of caudal peduncle 8.4–8.8% SL, body depth at anus 15.1–16.0% SL, snout length 48.0–52.9% HL, eye diameter 8.9– 9.9% HL, anterior nuchal plate strongly demarcated in beige and caudal peduncle with a pale vertical band. Glyptothorax strabonis n. sp. is distinguished from congeners in Indochina in having a very small eye (6.2–6.5% HL), and a combination of the following characters: length of caudal peduncle 20.5–21.2% SL, depth of caudal peduncle 7.5–9.2% SL, body depth at anus 13.7–20.9% SL, head width 17.9–18.8% SL, presence of 14–16 serrae on posterior margin of pectoral spine, and coloration consisting of a dark-brown body with indistinct pale mid-lateral and mid-dorsal stripes.

Two new species of snakes previously identified as Ninia atrata are described from Central America. A new species from Costa Rica and western Panama is distinguished from the other atrata group members by its low number of ventral and subcaudal scales, strongly reduced parietal scales, and small eye, whereas the new species from Honduras and El Salvador is distinguished from the other forms most easily by its lack of a pale nuchal collar and the possession of numerous tubercles on the parietal scales. A brief discussion on some of the morphological variation in the species N. atrata is also presented. Presently, the species Ninia atrata is thought to occur in disjunct populations from Honduras and El Salvador southward to Ecuador and Ven- ezuela (Savage and Lahanas, 1991). Examination by us of all the available Central American spec- imens of atrata-like snakes (including several other specimens erroneously identified as N. atrata previously) and a series of N. atrata from South America indicates that the specimens from Costa Rica and wester Panama, on the one hand, and those from Honduras and El Salvador on the other, represent two undescribed species of Ninia.

PHYSICAL BASIS OF GENE EXPRESSION . ... ...... ... ... ........ . . . ... ... 362 DNA ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. . . . . .. . .. . . . . . . . . . . . . . . . . . . . . . . . ... . .. . . . .... ... . . . 362 RNA .... . . . . . . .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....... 363 Protein ......... ..... ......... ......... .... 364 SINGLE-GENE VARIATION .... . . . . . ........ ... 365 Enzymes .... . . . . . . . . . . . . ..... . . . . . . . . . . . . . . . ........ . . . . . . . . . . . . . . . . . . . . ...... ... . . . . . . . . . . . . . . . . .. . .. . ... .. . . . . . .. . . . .. ... ... 365 Antigens ..... . . . ... ... . . . . .. . . .. . .. .. . .. . .. . ... . . ... ..... ... . .. . .. . .. . .. . . ... . . .. . . . . . . . .... .. ... ... . . 366 Lethal Genes .... ..... ... ....... ..... ..... ..... 366 Yellow (A') .. .. ........ . . . . . . ...... . ........ . . . . . . . . . . . . . . . . . . . . . . ........ . . . . . . . . . . . . . . . . . . . . . . 366 T locus •.•..• 367 tl' (also t"") ..... . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . ... ... . . . ... ... .... . . . . .. .. .. . . . . . . . 368 to" 369 t' (also t'. "tl': and t'O) . . . . . . .. . . . . . . . . . . . . . . . . . . . ... . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 369 t"' (also 16 other to alleles) .... . . . . . . . . ... . . . . . . . . ... ... .. . . . . . . . .. . .... . . ... . . . . . . . .. . . . . . . .... . . . . . . ... 369 t' (also t'. t"". t ..... to") . . ... . .. . ..... . . . . . . . . . . . . . . . . . . . ...... ... ... . ... . . . . . . . . . . . . . . . . . . . . . . . . ......... 370 T 370 Other T alleles .. .. . . . . . ... . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . ... . . . . . . ... ... .... . . ....... ... . ... . . . . 371 tol (also to', tol'. to'l t07l, t>11) .. . . . 371 Conclusion ....... . . . .. .... . . . .. ... . .. ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371 Fused (Fu). Kinky (Fuki) ... . . . . . . . . . ... . . . . . ... . ... ... . . . . . . . . . . . . . . ... . . . ... . . . ... . . . . . . ... . .. . . . . . . . . . . . . . . . . . 372 c locus . . . . . . . . . . . . . ..... . . . . . . . . . . . . . ... . . . . . . . . . . .. . ... . . .... . . ... . . . . .. . .. . . . . .. . .. . .. . .. . ... 372 Short-ear lethals ........ . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . .. . .. . .. . .. . .. . .. . .. . .. . .. .. .. . .. .. . . .... . . 373 Blind (Bid) .. . . . . . ... .. . . . . . . . . . . . . .. .. . . . . . . . . . . .. .. .. . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373 Velvet coat (V e) ..... . ... . . . . . . . .. . . . . . . . . . . . . . ...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . 373 Waved coat (We) ... . .. . . . .. . . . . . . . . . . ... . . . . . . . . ... . . . ... . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373 Dickie's small eye (Dey) 373 Hydrocephalus-1 (hy-1) . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . ... . . . . . . . . . . . ... ... . . ... ... . . . . . . . . . . . . ... ....... .. . .. . 373 Oligosyndactylism (Os) . . . .. . ......... .. ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... ... . . . .. . . . . . . . .... . ....... . 374 Tail-short (Ts) . .. . . . . . . .. .. . . . . . . . .. . . . .. ... . . . . . . . . . . . .. . . . ... . . . . . . . . . . . . . . . . . ... . . . . . . . . ...... . . . ... . . . . 374 Ovum mutant (am) . . . . . . . . . . . . .. .. . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . ....... ... ... . . . . 374 CHROMOSOME EFFECTS ...... .. . . . . . . . . . . . . ....... . . . . . ...... ... . . . . . ..... ... . . . . . . .... ... ..... .. . . . . 375 Single Chromosomes 375 Chromosome Sets ... ... . . . ........ . . . . . . . ....... ... . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . ..... . . . . . . . . . . . . . . . . . .... . .. . 377 CONCLUSIONS . . . . . . . . . . . . . ... . . . . . . . . . . . .. ... . . . . . . . . . . . . . .... ... . . . . . . . . . . ..... . . ........ ..... ........ 380

Five species of the marine New Zealand genus Hemerocoetes are recognised and described: H. monopterygius (Schneider) [= H. acanthorhynchus (Forster)]; H. morelandi n.sp.; H. pauciradiatus Regan; H. artus n.sp.; and H. macrophthalmus Regan. H. waitei Regan is placed in synonymy with H. macrophthalmus. H. morelandi differs from the two other species possessing a relatively wide interorbital and small eye in lacking a dorsal iris flap and (mature males) in having an elongate first dorsal fin ray. It differs from H. monopterygius in having an elongate barbel at the tip of the upper jaw in mature males, and from most specimens of H. pauciradiatus in having 36–38 anal fin rays. H. morelandi is known primarily from off the Auckland Islands and Campbell Island, whereas H. monopterygius is widespread around the North and South Islands and the Chatham Islands, and H. pauciradiatus is commonest off the southern portion of the South Island and off the Chatham Islands. H. artus differs most noticeably from th...

Parotocinclus arandai, new species of the hypoptopomatine catfish, is described from small creeks in the upper rios Jucuruçu and Buranhém basins, at the border of Brazilian States of Bahia and Minas Gerais. Parotocinclus arandai is distinguished from all congeners from the Atlantic coastal basins of southeastern and eastern Brazil, except Parotocinclus bahiensis, by having the branched rays and interradial membranes of the pectoral and pelvic fins unpigmented in ventral view. The new species is distinguished from most Parotocinclus species, by having a small eye, 14.8-19.3 mm HL (except P. maculicauda and P. planicauda) and by the presence of a tuft of hypertrophied odontodes on the supraoccipital (except P. cristatus and P. cesarpintoi). Parotocinclus arandai is further distinguished by having an abdomen extensively naked, with a mosaic of few rounded platelets of irregular size and distributed over the pre-anal region (except P. bahiensis, P. minutus, P. spilosoma, P. cearensis, P. cesarpintoi and P. prata). A detailed comparison with congeners on eastern Brazil hydrographical region is provided, and information on the species habitat is given. Parotocinclus arandai, espécie nova de cascudo hypoptopomatíneo, é descrita de pequenos riachos do curso superior das bacias dos rios Jucuruçu e Buranhém, na divisa estadual de Minas Gerais com a Bahia. Parotocinclus arandai é distinguida de todos os congêneres nas bacias costeiras do Atlântico do sudeste e leste do Brasil, exceto Parotocinclus bahiensis, por apresentar os raios ramificados e as membranas interradiais das nadadeiras peitoral e pélvica despigmentadas em vista ventral. A nova espécie é distinguida da maioria das espécies de Parotocinclus, por apresentar olho pequeno, 14.8-19.3 mm HL (exceto P. maculicauda e P. planicauda) e pela presença de um tufo de odontódes hipertrofiados no supraoccipital (com exceção a P. cristatus e P. cesarpintoi). Parotocinclus arandai é ainda distinguida pelo abdômen com extensas áreas nuas, apresentando um mosaico de poucas plaquinhas arredondadas de tamanho irregular e distribuídas na região pré-anal (exceto em P. bahiensis, P. minutus, P. spilosoma, P. cearensis, P. cesarpintoi e P. prata). Uma comparação detalhada com os congêneres na região hidrográfica do Leste do Brasil é apresentada e, adicionalmente são fornecidas informações acerca dos ambientes em que foram encontrados os cascudinhos.

We employed neutralizing infrared videophotorefraction and photokeratometry to examine the manifest refractions and corneal curvatures of 21 species of anurans (frogs and toads) in five families (Dendrobatidae, Bufonidae, Centrolenidae, Leptodactylidae, and Hylidae) resident in Central America. We found that all of the annurans exhibited hyperopic refractions in air, but that the observed hyperopia was not totally explained by the small eye artefact (Glickstein & Millodot, 1970). An allometric comparison of the corneal radii of these small anurans with those of a large number of other vertebrates, inferred from ocular axial lengths, showed that their corneal radii increased significantly more rapidly with increasing body size than that of other vertebrates generally (allometric slope constants: anurans: 0.270 ± 0.032; other vertebrates: 0.151 ± 0.004). Among the anurans examined, nocturnal Hylids had significantly larger eyes than diurnal Dendrobatid frogs and Bufonid toads.

Mutations in the Pax6 gene disrupt telencephalic development, resulting in a thin cortical plate, expansion of proliferative layers, and the absence of the olfactory bulb. The primary defect in the neuronal cell population of the developing cerebral cortex was analysed by using mouse chimeras containing a mixture of wild-type and Pax6-deficient cells. The chimeric analysis shows that Pax6 influences cellular activity throughout corticogenesis. At early stages, Pax6-deficient and wildtype cells segregate into exclusive patches, indicating an inability of different cell genotypes to interact. At later stages, cells are sorted further based on telencephalic domains. Pax6-deficient cells are specifically reduced in the mediocaudal domain of the dorsal telencephalon, indicating a role in regionalization. In addition, Pax6 regulates the process of radial migration of neuronal precursors. Loss of Pax6 particularly affects movement of neuronal precursors at the subventricular zone/intermediate zone boundary at a transitional migratory phase essential for entry into the intermediate zone. We suggest that the primary role of Pax6 is the continual regulation of cell surface properties responsible for both cellular identity and radial migration, defects of which cause regional cell sorting and abnormalities of migration in chimeras.

A semidominant mutation in the laboratory mouse, Coloboma (Cm), is described. Coloboma is located on Chromosome 2, as is the similar mutation Dickie's small eye (Dey). Coloboma has a moderately reduced expressivity. The anterior chamber is usually present in Cm/+. Both Cm and Dey show delayed detachment of the lens vesicle and microphthalmia, and homozygotes of both apparently die early in pregnancy.

Behavioral measures of spatial summation in 4- and 11-week old human infants were obtained using the forced-choice preferential looking technique. Infants exhibit complete spatial summation over large areas (4 weeks: 8.9 degrees; 11 weeks: 5.5 degrees), much larger than those of adults tested in the same apparatus (2.6 degrees). Thus, infants' summation areas are larger than adults' by factors of 12 at 4 weeks and 4 at 11 weeks. It is argued that at most, one-half of this difference between the infant and adult data may be due to optical factors (e.g. defocus and small eye size). The remainder probably reflects differences in the neural organization of the immature and mature visual systems.

The functional synaptic relationships in a system of neuronal connexions linking the two optic tecta in Xenopus laevis may change following rotation of one eye. This ability of the intertectal connexions to adjust to an altered spatial relationship between the two eyes was examined at various developmental stages. It was found that the system could respond to eye rotations as large as 180° provided that such rotations were performed before stage 58. The system did not respond even to small eye rotations if the latter were performed in adult life. For eye rotations performed during metamorphic climax (stages 60–66), alterations of intertectal connexions occurred if the rotations were 90° or less but not if the rotation were larger than 90°. The capacity of the intertectal system to modify its pattern of connexions in response to changes in the relative positions of the two eyes thus reduces with increasing age. A possible role, for this intertectal plasticity, in normal development is discussed.

A case of partial monosomy of the 13p terminal to 13q12, associated with a de novo 13/18 translocation, is reported. The symptoms appeared to be derived from both 18q- and partial monosomy 13, the latter giving rise to: high arched palate, epicanthus, antimongolian slant, small eye fissure, flat nasal bridge, hypoplastic helix, and large clitoris. Serum Ig-A and Ig-M levels were normal in our case.

Mice heterozygous for Dickie's small eye (Dey) are small and have malformed eyes (Theiler et al. 1978). The development of homozygous Dey/Dey was more difficult to analyze than heterozygous Dey/+. This investigation attempted to identify the homozygotes and to distinguish them from Dey/+ and +/+ resorptions. Such a distinction was possible only when enough specimens were available. The mutants are poor breeders and the collection of the necessary material has taken several years.

Small eye (Sey) is a dominant mutation in the mouse affecting the embryonic development of the eyes and nose. In homozygous Sey/Sey embryos, the optic vesicles grow out but there is no lens induction and the nasal pits fail to develop. Scanning electron microscope studies of Sey/ Sey embryos show that the maxillary processes develop normally and fuse with ridges of ectoderm in the frontonasal position. In Sey/ + heterozygotes, the vacuolated lens is smaller than normal, and there is folding of the margins of the optic cup and ingrowth of mesodermal cells. Evidence is presented that Sey is not allelic with Coloboma (Cm), another mutation affecting eye development on chromosome 2.