Pseudomma heardi, a New Peracarid (Crustacea: Mysidacea) from Continental Shelf Waters Off Mississippi

Pseudomma heardi n. sp. is described and illustrated. Specimens were obtained from plankton samples taken in 18 to 60 meters depth in offshore waters of Mississippi. This new species can be distinguished from other species of Pseudomma by the presence of 16 to 21 serrations on the anterior and lateral margins of the ocular plate, strong lateral spine of antennal scale which extends well beyond apex of scale and 4 to 6 spines on lateral margins of telson

Pseudomma heardi, a New Peracarid (Crustacea: Mysidacea) from Continental Shelf Waters Off Mississippi

Pseudomma heardi n. sp. is described and illustrated. Specimens were obtained from plankton samples taken in 18 to 60 meters depth in offshore waters of Mississippi. This new species can be distinguished from other species of Pseudomma by the presence of 16 to 21 serrations on the anterior and lateral margins of the ocular plate, strong lateral spine of antennal scale which extends well beyond apex of scale and 4 to 6 spines on lateral margins of telson

Relationship Between BP (\u3ci\u3eBaculovirus penaei\u3c/i\u3e) Energy Reserves in Larval and Postlarval Pacific White Shrimp \u3ci\u3ePenaeus vannamei\u3c/i\u3e

The relationship between energy reserves of the penaeid shrimp Penaeus vannamei and Baculovirus penaei, or BP, were investigated in a series of experiments using mysis stage or early postlarval shrimp. Pre-exposure and post-exposure levels of protein and triacylgycerol (TAG) were determined. The effect of pre-exposure protein and TAG levels on susceptibility to BP infections was also investigated by starving a group of shrimp immediately prior to BP exposure. There was no consistent relationship between either pre-exposure or post-exposure protein levels and the percent of shrimp developing patent BP infections. There was, however, a significant positive correlation between TAG levels immediately prior to viral exposure and prevalence of infection 72 h later. Experimental reduction of TAG reserves prior to BP exposure delayed the development of a patent infection. In some, but not all, experiments there was a significant reduction in TAG levels of infected compared with uninfected shrimp 72 h post-exposure. The effect of patent BP infections on host TAG levels was subordinate to fluctuations in TAG content associated with the ontogeny of the hepatopancreas. Results of this study support histological observations that shrimp lipid levels can be altered by baculovirus infections. Furthermore, high levels of energy reserves in the form of TAG are associated with increased susceptibility to BP infection in larval and postlarval shrimp

Apical Sarcomere-like Actomyosin Contracts Nonmuscle Drosophila Epithelial Cells

Actomyosin networks generate contractile force that changes cell and tissue shape. In muscle cells, actin filaments and myosin II appear in a polarized structure called a sarcomere, in which myosin II is localized in the center. Nonmuscle cortical actomyosin networks are thought to contract when nonmuscle myosin II (myosin) is activated throughout a mixed-polarity actin network. Here, we identified a mutant version of the myosin-activating kinase, ROCK, that localizes diffusely, rather than centrally, in epithelial cell apices. Surprisingly, this mutant inhibits constriction, suggesting that centrally localized apical ROCK/myosin activity promotes contraction. We determined actin cytoskeletal polarity by developing a barbed end incorporation assay for Drosophila embryos, which revealed barbed end enrichment at junctions. Our results demonstrate that epithelial cells contract with a spatially organized apical actomyosin cortex, involving a polarized actin cytoskeleton and centrally positioned myosin, with cell-scale order that resembles a muscle sarcomere.National Institutes of Health (U.S.) (GM06806)American Heart Association (Grant-in-aid 14GRNT1888005)American Cancer Society (grant 125792-RSG-14-039-01-CS)National Institutes of Health (U.S.) (Pre-Doctoral Training Grant T32GM00728

Observations on the Distribution and Seasonality of Portunid Megalopae in Mississippi Coastal Waters

Observations on the distribution and seasonality of common coastal portunid megalopae are presented. Callinectes sapidus megalopae were abundant from May through November. The megalopae of C. similis, though present throughout the year, peaked in numbers from February through April. With the exception of January, Portunus spp. megalopae occurred in all months, with maximum numbers collected in April. Callinectes sapidus megalopae commonly occurred at all stations, whereas, the megalopae of C. similis and Portunus spp. appeared to be limited by salinity

Effect of \u3ci\u3eBaculovirus penaei\u3c/i\u3e on Growth and Survival of Experimentally Infected Postlarvae of the Pacific White Shrimp, \u3ci\u3ePenaeus vannamei\u3c/i\u3e

In a series of experiments conducted to investigate age and size-dependent effects of the baculovirus BP on postlarvae of the Pacific white shrimp, Penaeus vannamei, six groups of specific pathogen-free shrimp of different ages (mysis 2–3 through PL 25) were exposed to the virus and cultured for 15 to 21 days. All BP-exposed groups of early postlarvae (PL 9 or younger) became heavily infected within 2–5 days of initial exposure to the virus, and some of those groups experienced high mortalities compared to the noninfected controls. Postlarvae that survived the infection had highly variable and significantly reduced growth, as determined by dry weight, compared to controls. Exposure of older postlarvae to BP produced a high prevalence of infection but with little effect on either survival or growth. One group of shrimp exposed to BP at PL 9 was cultured for 49 days. Postlarvae that survived the infection were significantly smaller than the noninfected controls for the first 4 weeks following exposure to the virus; however, the effect of BP on long-term growth of infected postlarvae appeared minimal. To determine the effect of BP on nutritionally stressed shrimp, groups of noninfected and previously infected postlarvae (PL 13–14) of similar size were deprived of food for 10 days. Less than 2% of the infected postlarvae survived the 10-day starvation period compared to 52% survival of the noninfected postlarvae

Actomyosin Pulsing in Tissue Integrity Maintenance during Morphogenesis

The actomyosin cytoskeleton is responsible for many changes in cell and tissue shape. For a long time, the actomyosin cytoskeleton has been known to exhibit dynamic contractile behavior. Recently, discrete actomyosin assembly/disassembly cycles have also been observed in cells. These so-called actomyosin pulses have been observed in a variety of contexts, including cell polarization and division, and in epithelia, where they occur during tissue contraction, folding, and extension. In epithelia, evidence suggests that actomyosin pulsing, and more generally, actomyosin turnover, is required to maintain tissue integrity during contractile processes. This review explores possible functions for pulsing in the many instances during which pulsing has been observed, and also highlights proposed molecular mechanisms that drive pulsing

New Records of Hyperiidea (Crustacea: Amphipoda) from the North Central Gulf of Mexico

Records of 54 species of amphipods of the suborder Hyperiidea from the Gulf of Mexico are presented. Forty-seven species are recorded from the Gulf for the first time. Previous records of occurrence in the Gulf of Mexico, Caribbean Sea, and associated North Atlantic waters are provided for each species

Records and Range Extensions of Mycidacea from Coastal and Shelf Waters of the Eastern Gulf of Mexico

Records of seventeen species of Mysidacea from the Gulf of Mexico are presented. Bowmaniella portoricensis, Pseudomma sp., Siriella thompsonii and Bathymysis renoculata are recorded from the Gulf for the first time. Range extensions within the Gulf are established for Anchialina typica and Mysidopsis furca. Records of Brasilomysis castroi and Mysidopsis almyra from the Atlantic coast of the United States are reported

Infectivity and Pathogenicity of \u3ci\u3eBaculovirus penaei\u3c/i\u3e (BP) in Cultured Larval and Postlarval Pacific White Shrimp, \u3ci\u3ePenaeus vannamei\u3c/i\u3e, Related to the Stage of Viral Development

The infectivity and pathogenicity of the penaeid shrimp virus, Baculovirus penaei (BP), is influenced by the stage of viral development. This study consisted of a preliminary experiment which showed that nonoccluded virus administered per os is infective, followed by two infectivity experiments. In the first phase of each infectivity experiment, mysis stage larvae of Penaeus vannamei were inoculated with BP and samples of infected tissue were collected at various times postinoculation (p.i.). These samples were then used to inoculate either mysis or postlarval stage P. vannamei in the second phase of each experiment. Viral inocula prepared from patently infected tissues consistently produced infections in both mysis and postlarval stage shrimp. Inocula prepared from prepatently infected tissue collected 12–18 h p.i. produced infections in some but not all replicate cultures, while inocula prepared from tissues collected earlier than 12 h p.i. were not infective. Viral development in mysis stage larvae was substantially delayed and the mortality was significantly lower when the viral inocula were prepared from prepatently compared to patently infected tissues. BP appears to be most pathogenic to larvae that have been exposed to inocula prepared from tissues that had recently developed a high prevalence of patent infections or about 72 h p.i