DETECTION OF SPECIES-SPECIFIC CALLS IN NOISE BY ZEBRA FINCHES POEPHILA GUTTATA AND BUDGERIGARS MELOPSITTACUS UNDULATUS: TIME OF FREQUENCY DOMAIN?

ABSTRACT

Two zebra finches and two budgerigars were trained, by operant conditioning, to detect autogenous (self-generated) distance calls in the presence of masking noise. For both species, there were no differences in detection thresholds for normal calls compared to time- reversed calls. Thresholds for autogenous calls were also compared with thresholds of the other species of birds listening to the same call. When detecting a zebra finch call, budgerigars had slightly lower thresholds than that of the zebra finch. On the other hand, when detecting a budgerigar call, zebra finches showed significantly higher thresholds than the budgerigar. From these results, and from what is known about basic hearing capabilities in these species, we conclude that these birds are not using a mechanism which utilizes “matched” or cross-correlational filtering. It is more likely that they are using “frequency-based” filtering in detecting calls in noise.     

Pattern of sperm storage and migration in the reproductive tract of the swallowtail butterfly Papilio xuthus: cryptic female choice after second mating

Females of the swallowtail butterfly Papilio xuthus L. (Lepidoptera: Papilionidae) mate multiply during their life span and use the spermatophores transferred to increase their longevity as well as fecundity. Sperm from different males may be stored in the sperm storage organs (bursa copulatrix and spermatheca). To clarify the pattern of sperm storage and migration in the reproductive tract, mated females are dissected after various intervals subsequent to the first mating, and the type and activity of sperm in the spermatheca are observed. When virgin females are mated with virgin males, the females store sperm in the spermatheca for more than 10 days. Sperm displacement is found in females that are remated 7 days after the first mating. Immediately after remating, these females flush out the sperm of the first male from the spermatheca before sperm migration of the second male has started. However, females receiving a small spermatophore at the second mating show little sperm displacement, and the sperm derived from the small spermatophore might not be able to enter the spermatheca. Females appear to use spermatophore size to monitor male quality.     

Disjunctive distribution of the basal genus Aplomerus (Hymenoptera: Ichneumonidae: Xoridinae) in East Asia and North America,with a new species from Japan

The first Japanese representative of the predominantly Nearctic genus Aplomerus Provancher, A. japonicus sp. nov., is described. This species can easily be distinguished from the other species by the black body. Morphologically this species resembles A. lineatulus (Say) from eastern North America but is separable by the sculpture of the propodeum and third metasomal tergite. The discovery of this species demonstrates a disjunctive distribution of the genus Aplomerus in East Asia and North America. Notes on habitat and adult behavior are also given.     

STRUCTURE AND FORMATION OF THE COLLAR IN CHOANOCYTES OF TETILLA SERICA (LEBWOHL), DEMOSPONGE

There are two types of collar in the choanocytes of adult Tetilla serica : one type is a continuous cytoplasmic tube and the other consists of discontinuous microvilli. The former is found in the small flagellated chamber and is considered to belong to a young choanocyte in the process of differertiation. To confirm this idea, very young choanocytes which are about to differentiate the collar were examined during embryogenesis.
The youngest choanocytes are noticed forming aggregations of small cells in 3-day larvae. Around the flagellum in each choanocyte, there is a depression which will become wider. At first, the collar is observed as a ring of cytoplasm; next this extends outward and becomes thinner, and finally it divides into microvilli. The microvillous collar is formed by the opening of vesicles and fusion of their membranes. These vesicles are considered to be derived from the Golgi complex. The process of collar formation through fusion of vesicles is discussed.     

Arsenic alters uptake and distribution of sulphur in Pteris vittata

Low‐molecular‐weight thiol (LMWT) synthesis has been reported to be directly induced by arsenic (As) in Pteris vittata, an As hyperaccumulator. Sulphur (S) is a critical component of LMWTs. Here, the effect of As treatment on the uptake and distribution of S in P. vittata was investigated. In P. vittata grown under low S conditions, the presence of As in the growth medium enhanced the uptake of SO₄^2?, which was used for LMWT synthesis in fronds. In contrast, As application did not affect SO₄^2? uptake in Nephrolepis exaltata, an As non‐hyperaccumulator. Moreover, the isotope microscope system revealed that S absorbed with As accumulated locally in a vacuole‐like organelle in epidermal cells, whereas S absorbed alone was distributed uniformly. These results suggest that S is involved in As transport and/or accumulation in P. vittata. X‐ray absorption near‐edge structure analysis revealed that the major As species in the fronds and roots of P. vittata were inorganic As(III) and As(V), respectively, and that As–LMWT complexes occurred as a minor species. Consequently, in case of As accumulation in P. vittata, S possibly acts as a temporary ligand for As in the form of LMWTs in intercellular and/or intracellular transport (e.g. vacuolar sequestration).     

IMMUNOCHEMICAL STUDY ON THE SPECIES SPECIFICITY OF SPERM-BINDING PROTEIN FROM THE SURFACE OF THE SEA URCHIN EGG*

Immunological species specificity of sperm-binding protein from eggs of the 4 sea urchin species, Hemicentrotus pulcherrimus, Pseudocentrotus depressus, Anthocidaris crassispina and Temnopleurus toreumaticus, was examined by means of double immuno-diffusion technique in agar. Ca-soluble fraction of sperm-binding protein which is considered to be responsible for initial sperm-egg bonding at fertilization, has species-specific antigenic component. Correlations in antigenic constituents among the 4 species are described.